Speech Perception in Classroom Acoustics by Children With Cochlear Implants and With Typical Hearing Purpose This study measured speech perception ability in children with cochlear implants and children with typical hearing when listening across ranges of reverberation times (RTs) and speech-to-noise ratios. Method Participants listened in classroom RTs of 0.3, 0.6, and 0.9 s combined with a 21-dB range of speech-to-noise ratios. ... Research Article
EDITOR'S AWARD Open Access
Research Article  |   June 01, 2016
Speech Perception in Classroom Acoustics by Children With Cochlear Implants and With Typical Hearing
 
Author Affiliations & Notes
  • Frank Iglehart
    Clarke Schools for Hearing and Speech, Northampton, MA
  • Disclosure: The author has declared that no competing interests existed at the time of publication.
    Disclosure: The author has declared that no competing interests existed at the time of publication. ×
  • Correspondence to Frank Iglehart: frank.iglehart@gmail.com
  • Editor and Associate Editor: Larry Humes
    Editor and Associate Editor: Larry Humes×
Article Information
Hearing & Speech Perception / Acoustics / Hearing Disorders / Hearing Aids, Cochlear Implants & Assistive Technology / School-Based Settings / Research Articles
Research Article   |   June 01, 2016
Speech Perception in Classroom Acoustics by Children With Cochlear Implants and With Typical Hearing
American Journal of Audiology, June 2016, Vol. 25, 100-109. doi:10.1044/2016_AJA-15-0064
History: Received October 15, 2015 , Revised February 1, 2016 , Accepted February 3, 2016
 
American Journal of Audiology, June 2016, Vol. 25, 100-109. doi:10.1044/2016_AJA-15-0064
History: Received October 15, 2015; Revised February 1, 2016; Accepted February 3, 2016

Purpose This study measured speech perception ability in children with cochlear implants and children with typical hearing when listening across ranges of reverberation times (RTs) and speech-to-noise ratios.

Method Participants listened in classroom RTs of 0.3, 0.6, and 0.9 s combined with a 21-dB range of speech-to-noise ratios. Subsets also listened in a low-reverberant audiological sound booth. Performance measures using the Bamford-Kowal-Bench Speech-in-Noise Test (Etymotic Research, Inc., 2005) were 50% correct word recognition across these acoustic conditions, with supplementary analyses of percent correct.

Results Reduction in RT from 0.9 to 0.6 s benefited both groups of children. A further reduction in RT to 0.3 s provided additional benefit to the children with cochlear implants, with no further benefit or harm to those with typical hearing. Scores in the sound booth were significantly higher for the participants with implants than in the classroom.

Conclusions These results support the acoustic standards of 0.6 s RT for children with typical hearing and 0.3 s RT for children with auditory issues in learning spaces (≤283 m3) as specified in standards S12.60-2010/Part 1 of the American National Standards Institute /Acoustical Society of America (2010) . In addition, speech perception testing in a low-reverberant booth overestimated classroom listening ability in children with cochlear implants.

Children depend on acoustic access to their teachers and class discussions for academic success (American National Standards Institute [ANSI]/Acoustical Society of America [ASA], 2002, p. 10; Berg, 1987; Bronzaft, 1981; Bronzaft & McCarthy, 1975; Evans, Hygge, & Bullinger, 1995; Evans & Maxwell, 1997; Haines, Stansfeld, Job, Berglund, & Head, 2001; Lukas, 2001; Lukas, DuPree, & Swing, 1981; Taub, Kanis, & Kramer, 2003). Acoustic factors affecting speech perception—noise levels, speech-to-noise ratios (SNRs) and reverberation times (RTs)—vary widely during the school day (Bradley, 1986; Crandell & Smaldino, 1994; Knecht, Nelson, Whitelaw, & Feth, 2002; Larsen & Blair, 2008; MacKenzie & Airey, 1999; Shield & Dockrell, 2008). SNR is a measure of the sound level (dB) of speech in relation to background noise. RT is defined as the time in seconds for sound in a room to decrease in energy 60 dB after sudden termination (Beranek, 1988). Excessive noise and reverberation exist in classrooms from New Zealand (Blake & Busby, 1994) to North America (e.g., Bradley, 1986; Lukas, 2001) to Europe (e.g., Haines et al., 2001; MacKenzie & Airey, 1999; Skarlatos & Manatakis, 2003).
The detrimental effects of hearing loss on children's perception of speech (e.g., Blamey et al., 2001; Boothroyd, 1984) and the greater susceptibility to poor acoustics in children with typical hearing compared to adults are well known (e.g., Neuman, Wróblewski, Hajicek, & Rubinstein, 2010; Wróblewski, Lewis, Valente, & Stelmachowicz, 2012). Finitzo-Hieber and Tillman (1978)  reported on children with typical hearing whose speech perception benefited from a reduction in RT from 1.2 to 0.4 s, with no further significant benefit from reduction to 0.0 s. Some have reported higher RTs (0.68 s: Yang & Bradley, 2009) whereas others have reported lower RTs were most beneficial (e.g., 0.3 s: Neuman et al., 2010; 0.0 s: Neuman & Hochberg, 1983; Wróblewski et al., 2012; Yacullo & Hawkins, 1987).
The effects of reverberation and noise have been relatively less well understood with children with hearing loss (e.g., Picard & Bradley, 2001) and especially with those with cochlear implants (e.g., Neuman, Wróblewski, Hajicek, & Rubinstein, 2012) compared to children with typical hearing or adults. Finitzo-Hieber and Tillman (1978)  found that children with hearing loss using a hearing aid benefited significantly from each reduction in RT from 1.2 to 0.4 to 0.0 s. Neuman et al. (2012)  reported on children with cochlear implants listening to the Bamford-Kowal-Bench Speech-in-Noise Test (BKB-SIN; Etymotic Research, Inc., 2005) and scored by 50% correct word recognition (SNR-50), the SNR in which a listener correctly perceives 50% of words. The children's scores declined (improved) significantly with each reduction in RT from 0.8 to 0.6 s to a nonreverberant condition. These studies suggest but do not directly address whether the acoustic requirement in ANSI/ASA S12.60-2010/Part 1, table 1 (core learning spaces ≤283 m3, which is, for example, ≤12.0 × 7.9 × 3.0 m) of 0.3 s RT for children with auditory issues is appropriate for children with cochlear implants.
Much research on reverberation and speech perception has addressed other areas: adults (e.g., Harris & Reitz, 1985; Harris & Swenson, 1990; Helfer, 1994; Helfer & Huntley, 1991; Helfer & Wilber, 1990; Irwin & McAuley, 1987), adults with typical hearing when listening to simulated cochlear implantation (e.g., Poissant, Whitmal, & Freyman, 2006; Tillery, Brown, & Bacon, 2012), and adults with cochlear implants listening in simulated reverberation (e.g., Gifford et al., 2013; Mason & Kokkinakis, 2014; Spitzer, Sandridge, Newman, Sydlowski, & Ghent, 2015). Other studies have measured the effects of reverberation on speech perception in relation to the benefits of FM and infrared devices with children with hearing loss (e.g., Anderson & Goldstein, 2004) and without (Ross & Giolas, 1971).
Studies comparing listening in nonreverberant and reverberant environments for children with hearing loss have reported significant differences in scores between these conditions (Finitzo-Hieber & Tillman, 1978; Neuman et al., 2012). Finitzo-Hieber and Tillman (1978)  also reported no significant difference in scores for children with typical hearing between anechoic and reverberant listening conditions, whereas others reported mixed results (Wróblewski et al., 2012).
The paucity of data on speech perception in children with cochlear implants listening in reverberation mixed with noise and the wide range of RTs previously reported best for children with typical hearing raise the following questions addressed in this study.
  1. Are the differences significant in speech perception ability between children with cochlear implants and those with typical hearing when listening in the same classroom and sound booth RTs?

  2. Are the RT requirements in the ANSI/ASA (2010)  classroom acoustic standards suitable for both children with cochlear implants and those with typical hearing?

  3. Do speech perception scores obtained in a nonreverberant sound booth differ significantly from scores obtained in a classroom with a relatively low RT?

Method
Participants
Ten girls and 13 boys (M age = 11.1 years, age range 5.8–16.0 years) had bilateral severe-to-profound hearing loss and used cochlear implants (first implant: M age = 4.1 years, age range 1.0–14.3 years). Table 1 provides age, type of implant and processor, and other demographic information. Identification of hearing loss for nine children was at birth, for eight by age 1.5 years, and for six by age 3.3 years. Each child correctly perceived words in sentences ≥80% from the BKB-SIN test (Version 1.03; Etymotic Research, Inc., 2005) while listening in 0.3 s RT and ≤ +30 dB SNR. Table 2 provides mean ages at testing and durations of implant use for 12 children with bilateral implants and 11 with unilateral implants and unaided in the opposite ear. An additional 11 girls and 12 boys (M age = 11.1 years, age range 5.2–16.6 years) had typical hearing (pure-tone thresholds of ≤15 dB HL at octaves 500–4000 Hz). The study added testing in a sound booth midway through. The participants from the two groups tested in both classroom and sound booth were 14 children with cochlear implants (M age = 10.5 years, age range 5.7–15.9 years) and 10 with typical hearing (M age = 9.0 years, age range 5.9–15.9 years).
Table 1. Background information on participants with cochlear implants.
Background information on participants with cochlear implants.×
Participants
Implanted device
Processor Age at implantation
Cause of hearing loss
No. Age (Years) Gender Right ear Left ear Right Left
1 5.8 F Nucleus 24 Freedom Freedom 1.0 3.5 Connexin 26 mutation
2 7.0 F Freedom Unaided Freedom 2.9 Meningitis
3 7.0 F Nucleus 24 Nucleus 24 Freedom 6.5 5.4 Unknown
4 7.5 M HiRes 90K Unaided Harmony 2.4 Unknown
5 8.3 M Nucleus 24 Freedom Freedom 1.5 6.3 Connexin 26 mutation
6 8.7 F Harmony 3.6 7.6 Pendred's syndrome
7 8.8 M Nucleus 24 Freedom Freedom 2.3 7.8 Connexin 26 mutation
8 9.7 M Nucleus 24 Freedom Freedom 6.4 4.0 Unknown
9 10.8 F Unaided Nucleus 24 Freedom 5.0 Genetic
10 10.8 M Unaided Freedom 3.9 Unknown
11 10.8 F Freedom Unaided Freedom 8.4 Unknown
12 11.0 M Freedom 2.4 10.7 Cytomegalo virus
13 11.5 F Unaided Nucleus 24 Freedom 2.5 Connexin 26 mutation
14 11.5 F Nucleus 24 Freedom Freedom 8.8 2.8 Unknown
15 12.4 M Unaided ESPrit 3G 3.8 Suspected genetic
16 12.5 F HiRes 90K C II Auria 10.9 7.3 Unknown
17 12.7 F Nucleus 24 Unaided ESPrit 3G 3.7 Unknown
18 12.8 M C II HiRes 90K Harmony 5.5 11.5 Unknown
19 13.0 M Freedom Freedom Freedom 2.8 12.9 Unknown
20 15.7 M Nucleus 24 Unaided ESPit 3G 2.4 Cochlear malformation
21 15.8 M C I Unaided Platinum BTE 5.3 Meningitis
22 15.9 M HiRes 90K HiRes 90K Harmony 4.4 13.9 Unknown
23 16.0 M Unaided Freedom Freedom 14.3 Unknown
Note. Unaided = no implant or hearing aid; — = information not available. A small number of students required re-implantation; ages provided are for first implantation, whereas the model of implant device was in use at time of testing. All bilateral users were implanted sequentially and wore the same model processor on both ears.
Note. Unaided = no implant or hearing aid; — = information not available. A small number of students required re-implantation; ages provided are for first implantation, whereas the model of implant device was in use at time of testing. All bilateral users were implanted sequentially and wore the same model processor on both ears.×
Table 1. Background information on participants with cochlear implants.
Background information on participants with cochlear implants.×
Participants
Implanted device
Processor Age at implantation
Cause of hearing loss
No. Age (Years) Gender Right ear Left ear Right Left
1 5.8 F Nucleus 24 Freedom Freedom 1.0 3.5 Connexin 26 mutation
2 7.0 F Freedom Unaided Freedom 2.9 Meningitis
3 7.0 F Nucleus 24 Nucleus 24 Freedom 6.5 5.4 Unknown
4 7.5 M HiRes 90K Unaided Harmony 2.4 Unknown
5 8.3 M Nucleus 24 Freedom Freedom 1.5 6.3 Connexin 26 mutation
6 8.7 F Harmony 3.6 7.6 Pendred's syndrome
7 8.8 M Nucleus 24 Freedom Freedom 2.3 7.8 Connexin 26 mutation
8 9.7 M Nucleus 24 Freedom Freedom 6.4 4.0 Unknown
9 10.8 F Unaided Nucleus 24 Freedom 5.0 Genetic
10 10.8 M Unaided Freedom 3.9 Unknown
11 10.8 F Freedom Unaided Freedom 8.4 Unknown
12 11.0 M Freedom 2.4 10.7 Cytomegalo virus
13 11.5 F Unaided Nucleus 24 Freedom 2.5 Connexin 26 mutation
14 11.5 F Nucleus 24 Freedom Freedom 8.8 2.8 Unknown
15 12.4 M Unaided ESPrit 3G 3.8 Suspected genetic
16 12.5 F HiRes 90K C II Auria 10.9 7.3 Unknown
17 12.7 F Nucleus 24 Unaided ESPrit 3G 3.7 Unknown
18 12.8 M C II HiRes 90K Harmony 5.5 11.5 Unknown
19 13.0 M Freedom Freedom Freedom 2.8 12.9 Unknown
20 15.7 M Nucleus 24 Unaided ESPit 3G 2.4 Cochlear malformation
21 15.8 M C I Unaided Platinum BTE 5.3 Meningitis
22 15.9 M HiRes 90K HiRes 90K Harmony 4.4 13.9 Unknown
23 16.0 M Unaided Freedom Freedom 14.3 Unknown
Note. Unaided = no implant or hearing aid; — = information not available. A small number of students required re-implantation; ages provided are for first implantation, whereas the model of implant device was in use at time of testing. All bilateral users were implanted sequentially and wore the same model processor on both ears.
Note. Unaided = no implant or hearing aid; — = information not available. A small number of students required re-implantation; ages provided are for first implantation, whereas the model of implant device was in use at time of testing. All bilateral users were implanted sequentially and wore the same model processor on both ears.×
×
Table 2. Mean ages and durations of implant use for children with unilateral versus bilateral cochlear implant fittings.
Mean ages and durations of implant use for children with unilateral versus bilateral cochlear implant fittings.×
Years Range
Unilateral fittings (N = 11)
Age at testing 11.9 7.0–16.0
(10.7) (7.0–15.7)
Age at implant 4.9 2.4–14.3
(4.0) (2.5–8.4)
Duration of use 6.1 1.7–13.3
(6.8) (2.4–13.3)
Bilateral fittings (N = 12)
Age at testing 10.4 5.8–15.9
(10.9) (7.0–15.9)
Age at first implant 3.6 1.0–7.3
(3.8) (1.5–5.5)
Duration of first implant use 6.8 1.6–11.5
(7.1) (1.6–11.5)
Age at second implant 8.9 3.5–13.9
(9.3) (6.3–13.9)
Duration of second implant use 1.5 0.1–3.3
(1.6) (0.1–3.3)
Note. Data on the subsets of five unilaterally and eight bilaterally fitted children tested in both sound booth and classroom are in parentheses.
Note. Data on the subsets of five unilaterally and eight bilaterally fitted children tested in both sound booth and classroom are in parentheses.×
Table 2. Mean ages and durations of implant use for children with unilateral versus bilateral cochlear implant fittings.
Mean ages and durations of implant use for children with unilateral versus bilateral cochlear implant fittings.×
Years Range
Unilateral fittings (N = 11)
Age at testing 11.9 7.0–16.0
(10.7) (7.0–15.7)
Age at implant 4.9 2.4–14.3
(4.0) (2.5–8.4)
Duration of use 6.1 1.7–13.3
(6.8) (2.4–13.3)
Bilateral fittings (N = 12)
Age at testing 10.4 5.8–15.9
(10.9) (7.0–15.9)
Age at first implant 3.6 1.0–7.3
(3.8) (1.5–5.5)
Duration of first implant use 6.8 1.6–11.5
(7.1) (1.6–11.5)
Age at second implant 8.9 3.5–13.9
(9.3) (6.3–13.9)
Duration of second implant use 1.5 0.1–3.3
(1.6) (0.1–3.3)
Note. Data on the subsets of five unilaterally and eight bilaterally fitted children tested in both sound booth and classroom are in parentheses.
Note. Data on the subsets of five unilaterally and eight bilaterally fitted children tested in both sound booth and classroom are in parentheses.×
×
Participant recruitment was through presentations to cochlear implant parent groups hosted by medical centers, to parents of students attending schools in the region including the Clarke School, and through word of mouth. American English was the native language of all participants. No participants had suspected or diagnosed attention deficit disorder or learning disability. Approval for this study for human subjects' protection was obtained from the Smith College Institutional Review Board.
Test Materials
The BKB-SIN test contains 36 lists in 18 pairs, with either eight or 10 sentences per list and each sentence containing three to four target words. The BKB-SIN compact disc presents speech on one channel and background noise (four-talker babble) on a second channel. The SNR of the first sentence is +21 dB, with 3-dB decreases with each subsequent sentence in the list. The number of words in a list correctly perceived provides, through a formula, the listener's SNR-50 score for the list; a valid score is the average of SNR-50 scores from both lists in a pair.
Additional analyses of scores in each combination of RT and SNR, labeled in this study as RT–SNR scores, required lists of equal length for consistent test conditions within and between participants. It was necessary, therefore, to delete Sentences 9 and 10 in List Pairs 1–8, which likely had no significant effect on scores (M. Skinner, personal communication, December 10, 2006). Pretest assessments used List Pairs 1–3. Testing randomized the order of List Pairs 4–18 within and across the RT conditions and within and across participants.
Test Rooms
The test classroom—10.0 (L) × 6.7 (W) × 3.4 (H) m—had a total volume of 223.4 m3 (see Figure 1). Walls were plaster with blackboards and closed windows, the ceiling was plaster, and the floor was polished hardwood with a small nonpadded carpet. Each participant sat at a small desk approximating the center of the second row of a classroom and facing the speech loudspeaker. This loudspeaker was 1.5 m above the floor approximating the head position of a teacher when standing 0.7 m from the front-center of the room and 3.0 m in front of the participant. One of four noise loudspeakers faced each of the four corners of the room, 0.9 m from each corner and 1.5 m above the floor. Two response scorers sat to the right and left of the participant. The audiological test booth (International Acoustic Chamber, Inc.)—1.9 (L) × 1.8 (W) × 2.0 (H) m—had a total volume of 6.8 m3. Each participant sat in the booth 0.9 m from, and facing, speech and noise loudspeakers located immediately right and left of 0° azimuth and 1.0 m above the floor.
Figure 1.

The arrangement of the classroom with the student located near the center of the room, seated at a desk; two adult scorers were seated to the right and left. The speech loudspeaker was 0° azimuth to the student, with four noise loudspeakers, one facing each corner. The room also contained an alcove and several floor and wall cabinets.

 The arrangement of the classroom with the student located near the center of the room, seated at a desk; two adult scorers were seated to the right and left. The speech loudspeaker was 0° azimuth to the student, with four noise loudspeakers, one facing each corner. The room also contained an alcove and several floor and wall cabinets.
Figure 1.

The arrangement of the classroom with the student located near the center of the room, seated at a desk; two adult scorers were seated to the right and left. The speech loudspeaker was 0° azimuth to the student, with four noise loudspeakers, one facing each corner. The room also contained an alcove and several floor and wall cabinets.

×
Reverberation Times
The number and location of acoustic panels (All Noise Control, 2007; model ANC-600) determined the classroom RT. The RT was 0.9 s with no panels; 0.6 s with 12 panels hanging on the walls just below ceiling height; and 0.3 s with a total of 50 panels, 34 hanging on the walls just below ceiling height, eight near floor level, and eight panels on the floor. Each panel was 0.6 × 1.8 m, with manufacturer's noise reduction coefficients of 1.15 to 1.25. The measured RT of the audiological sound booth was 0.059 s.
The 0.9-s RT condition approximated the longer midrange of reported classroom RTs (Bradley, 1986; Crandell & Smaldino, 1994; Knecht et al., 2002; MacKenzie & Airey, 1999). The 0.6- and 0.3-s RT conditions address the requirements in ANSI/ASA (2010)  for children with and without auditory issues. The presentation order of the three RTs was counterbalanced within the group with cochlear implants and within the group with typical hearing. The participants listened in the classroom beyond the critical distances measured and calculated in each RT.
Speech and Noise Levels
A potentiometer on an audiometer (at first a GSI 10 and, later in classroom testing, a GSI 16; Grason-Stadler Inc., Eden Prairie, MN) controlled the level of target speech from the BKB-SIN test compact disc. A sound field system (Phonic Ear 210; Phonic Ear A/S, Smorum, Denmark) amplified the signal through the one speech loudspeaker (Phonic Ear 578-S). The calibration noise on the BKB-SIN compact disc measured at the seated participant's midhead position, 1.0 m above the floor, was the basis for speech and noise level measurements. The speech level for 16 participants with cochlear implants was 59.5 dBALeq in 0.6-s RT. All scored >80% in high SNRs. Seven other participants complained that sentences at 59.5 dBA could not be understood (in quiet), and this was substantiated by initially poor scores. Five of these children (Nos. 6, 9, 11, 18, and 23; see Table 1) reported a 3-dB increase to 62.5 dBA in speech level was satisfactory, and two (Nos. 10 and 22; see Table 1) were satisfied with a 6-dB increase, to 65.5 dBA. All seven participants subsequently scored >80% in high SNRs. Target SNRs required corresponding increases in noise levels.
The second channel of the audiometer controlled noise levels through a second sound system (Phonic Ear 210) and the four noise loudspeakers (Phonic Ear 578-S) described earlier. Head movements at the participants' position did not result in noticeable variations in noise level and thus suggested acoustic correlation did not occur. Listening checks at the speakers and the participants' position indicated equal noise levels from all directions. Nontest background noise measured before and after testing was <35 dBA.
SNR, RT, and Spectra Measurements
The RT and speech and noise levels were measured with a Larson Davis System 824 (Type 1; Larson Davis, Depew, NY) sound level meter. Each RT calculation was an average of one-third octave measurements at 500, 1000, and 2000 Hz (ANSI, 2002; see the online supplemental materials, Supplemental Table S1), using speech-shaped noise (Etymotic Research, Inc., 2005) to acoustically excite the room. The RT measurements followed procedures recommended in ASTM C423-02a1, appendix X2 (American Society for Testing & Materials Standards, 2003), with the exceptions that measurements were only at the participant's head position, and 160 Hz substituted for 125 Hz. Slapping two boards together in the sound booth created sufficient noise spectrum and decay to confirm the booth RT.
Speech and noise level were made on the basis of 20-s LeqA, the sound pressure level in dB when A-weighted over 20 s. These measurements also were made to 0.1 dB at the beginning of, and periodically confirmed throughout, the study. Each SNR was then rounded to the nearest decibel. Measurements with a calibrated Type 2 meter at the test midposition of a participant's head verified speech and noise levels before and after each session. In only one session did pre- and posttest levels differ more than 1.0 dB; the results were discarded.
The spectrum of noise varied from speech in the classroom and, separately, in the sound booth by 0.0 dB (within ±0.7 dB at each octave from 250–4000 Hz). The speech, and separately the noise, spectra varied between the classroom and the sound booth by 0.0 dB (within ±2.0 dB at each octave). All spectral outputs of speech and noise, therefore, were essentially the same.
Effects of RT on SNR
A change in acoustic panels affected noise levels more than speech (see Table 3), likely due to relatively close location of some acoustic panels to the noise speakers, and thus could confound the effects of RT with SNR on participants' scores. Related adjustments to noise levels maintained SNRs across changes in RT. For example, changing RT from 0.3 to 0.9 s increased speech levels by 2.6 dB and noise by 5.7 dB, for a net change in SNR of − 3.1 dB (see Table 3). A subsequent 3-dB decrease to the noise level maintained the original SNR.
Table 3. Changes in speech and noise levels resulting from changes in reverberation time.
Changes in speech and noise levels resulting from changes in reverberation time.×
RT Speech Noise Change in RT Speech Noise SNR a
0.9 60.8 61.3 change to 0.6 −1.3 −1.7 +0.4
0.6 59.5 59.6 change to 0.3 −1.3 −4.0 +2.7
0.3 58.2 55.6 change to 0.9 +2.6 +5.7 −3.1
Note. RT = reverberation time (s); SNR = speech-to-noise ratio (dBA)
Note. RT = reverberation time (s); SNR = speech-to-noise ratio (dBA)×
a These net changes in SNR with each change of RT were removed by adjustments in noise levels, thereby keeping SNRs constant across changes in RT.
These net changes in SNR with each change of RT were removed by adjustments in noise levels, thereby keeping SNRs constant across changes in RT.×
Table 3. Changes in speech and noise levels resulting from changes in reverberation time.
Changes in speech and noise levels resulting from changes in reverberation time.×
RT Speech Noise Change in RT Speech Noise SNR a
0.9 60.8 61.3 change to 0.6 −1.3 −1.7 +0.4
0.6 59.5 59.6 change to 0.3 −1.3 −4.0 +2.7
0.3 58.2 55.6 change to 0.9 +2.6 +5.7 −3.1
Note. RT = reverberation time (s); SNR = speech-to-noise ratio (dBA)
Note. RT = reverberation time (s); SNR = speech-to-noise ratio (dBA)×
a These net changes in SNR with each change of RT were removed by adjustments in noise levels, thereby keeping SNRs constant across changes in RT.
These net changes in SNR with each change of RT were removed by adjustments in noise levels, thereby keeping SNRs constant across changes in RT.×
×
Procedures
Each participant age ≥8 years listened to three list pairs of the BKB-SIN test in each RT. A SNR-50 score was an average of three list pairs, and each RT–SNR score was an average of six test sentences. Each participant age <8 years listened to only two list pairs per each RT to limit testing to less than 8 min to avoid fatigue or flagging attention (Hnath-Chisolm, Laipply, & Boothroyd, 1998). A change of panels from one RT condition to the next took 12–15 min and allowed a participant to take a break.
The study adapted the start (first sentence in a list) SNR to each participant. If scores declined five percentage points or more only after the third or fourth sentence in a list, the start SNR was high enough to capture the participant's optimal performance and low enough to produce a full range of scores across the 21-dB decline in SNRs. The use of start SNRs other than +21 dB required adjustments to the SNR-50 calculations provided in the BKB-SIN manual. The manual (Etymotic Research, Inc., 2005, p. 23) states that “the starting point (21 dB) plus half of the step size (1.5), plus the extra word in the first sentence … equals 23.5. SNR-50 is 23.5 minus the total number of words repeated correctly.” In this study, when the start SNR was, for example, 3 dB above +21 dB SNR, the SNR-50 was calculated as equal to 23.5 plus 3 minus the number of correctly perceived words. If the start SNR was 3 dB below +21 dB SNR, SNR-50 equaled 23.5 minus 3 minus the number of words correct.
In the classroom, the interscorer reliability between the two scorers when listening to children with cochlear implants was 96.4% and with those with typical hearing was 98.5%. Whenever scorers differed on words correct in a sentence, the sentence score was the lower of the two. The author was always one of the scorers, and the second scorer was one of four people, all familiar with the children's speech. Scorers judged a child's misarticulation as correct only if it had been observed in earlier conversations and could be considered to represent a correct response. In the sound booth, only the scorer in booth could clearly hear participants' responses over the background test noise. Sound booth testing, thus, involved only one scorer. This likely had negligible effect on reliability given the high interscorer reliability observed in the classroom. The scorer in the booth always scored the same child in the classroom.
Results
SNR-50 Score Comparisons
The first analysis of classroom-only results used a 3 × 1 repeated measures design with three levels of RT as the first factor and one level of SNR-50 score as the second, with SNR-50 scores as the dependent variable. Analyses of sound booth and classroom results used a 4 × 1 repeated measures design with four levels of RT and one level of SNR-50. The main effect of RT on speech perception between the group with cochlear implants and those with typical hearing was significant (repeated measures analysis of variance) across the three classroom RTs, F(1, 44) = 285.37, p < .001, and between subgroups across the classroom RTs and sound booth, F(1, 21) = 95.27, p < .001. The SNR-50 scores for the children with cochlear implants were significantly higher (required substantially higher SNRs for the same performance) in post hoc analysis, (Fisher's least significance difference) all p < .001, compared to the children with typical hearing (see Figure 2): 12.2 dB in 0.3-s, 13.2 dB in 0.6-s, 14.6 dB in 0.9-s RT, and 7.9 dB in the sound booth. Mean, standard deviation, and sample number (N) for SNR-50 scores by RT for each group are provided in the online supplemental materials, Supplemental Table S2.
Figure 2.

Calculated speech-to-noise ratios (SNRs) for SNR-50 in children with cochlear implants (CI) and children with typical hearing (TH) in three classroom reverberation times (RTs) and subgroups of these children in the sound booth (SB). Error bars represent standard errors.

 Calculated speech-to-noise ratios (SNRs) for SNR-50 in children with cochlear implants (CI) and children with typical hearing (TH) in three classroom reverberation times (RTs) and subgroups of these children in the sound booth (SB). Error bars represent standard errors.
Figure 2.

Calculated speech-to-noise ratios (SNRs) for SNR-50 in children with cochlear implants (CI) and children with typical hearing (TH) in three classroom reverberation times (RTs) and subgroups of these children in the sound booth (SB). Error bars represent standard errors.

×
SNR-50 Scores for Participants with Cochlear Implants
The main effect of RT on the basis of SNR-50 scores across the classroom RTs for the group with cochlear implants (N = 23) was significant, F(2, 44) = 57.47, p < .001. Each decrease (improvement) in SNR-50 scores with a reduction in classroom RT, from 0.9 to 0.6 to 0.3 s, was significant in post hoc analysis, all p ≤ .005. For the subgroup with cochlear implants (n = 13) tested in both the classroom and the sound booth, the main effect of RT across sound booth and three classroom RTs was significant, F(3, 36) = 33.33, p < .001. The differences in scores in post hoc analyses between the sound booth and each of the three classroom RTs were all significant, all p ≤ .001.
SNR-50 Scores for Participants with Typical Hearing
The main effect of RT on the basis of SNR-50 scores across classroom RTs for the group with typical hearing (N = 23) was significant, F(2, 44) = 14.08, p < .001. Only the decrease in score from 0.9- to 0.6-s RT was significant in post hoc analysis, p < .001. The decrease in score from 0.6-s to 0.3-s RT was not significant, p = .525. The main effect of RT for the subgroup with typical hearing (n = 10) tested in both the classroom RTs and sound booth was significant, F(3, 27) = 3.10, p = .043. The differences in scores in post hoc analyses between the sound booth and each of the three classroom RTs were all nonsignificant, all p ≥ .131.
RT–SNR Scores for Participants with Cochlear Implants
A second analysis of classroom-only results used a 3 × 8 repeated measures design with three levels of classroom RTs and eight levels of RT–SNR scores, with RT–SNR scores as the dependent variable. A second analysis across the classroom and sound booth used a 4 × 8 repeated measures design with four levels of RT and eight levels of RT–SNR scores. The main effect of classroom RT on speech perception scores for participants with cochlear implants (N = 20–21) was significant, F(2, 38) = 47.40, p < .001. The main effect of SNR was also significant, F(4, 76) = 26.71, p < .001. Scores improved significantly between 0.9- and 0.6-s RT, F(1, 19) = 41.02, p < .001, and across SNRs, F(4, 76) = 15.59, p < .001, and between 0.6- and 0.3-s RT, F(1, 20) = 5.99, p = .023, and across SNRs, F(4, 80) = 21.69, p < .001. There was no significant interaction between RT and SNR in any of these analyses. These second analyses allowed calculations of performance-intensity functions provided in Figure 3 for further insights (Boothroyd, 2008). In the online supplemental materials, Supplemental Table S3 provides mean, standard deviation, and N for scores from 0 to +21 dB SNR by RT.
Figure 3.

Mean scores plotted as performance/intensity curves by reverberation time (RT) and speech-to-noise ratio for children with cochlear implants (CI) and children with typical hearing (TH) when listening in the classroom. Error bars represent standard errors.

 Mean scores plotted as performance/intensity curves by reverberation time (RT) and speech-to-noise ratio for children with cochlear implants (CI) and children with typical hearing (TH) when listening in the classroom. Error bars represent standard errors.
Figure 3.

Mean scores plotted as performance/intensity curves by reverberation time (RT) and speech-to-noise ratio for children with cochlear implants (CI) and children with typical hearing (TH) when listening in the classroom. Error bars represent standard errors.

×
Post hoc analyses then addressed the effects between RT and SNR on scores in the classroom (see Figure 3). For example, a decrease in RT from 0.6 to 0.3 s without an increase in SNR yielded an improvement in scores significant only within +21 dB SNR, p = .027, and not in the other SNRs from +9 to +18 dB, all p ≥ .084. Likewise, a 3-dB increase in SNR with no change in 0.6-s RT yielded significant benefit only from +18 to +21 dB SNR, and not in the other 3-dB increases, all p ≥ .069. Further significant improvements in scores occurred with a combination of change in RT from 0.6 to 0.3 s and changes in SNR from +9 to +12, +12 to +18, +15 to +21, and +18 to +21 dB, all p ≤ .042.
For scores by the subgroup using cochlear implants (n = 13) tested in both the sound booth and classroom, the main effects across all four RTs were significant for RT, F(3, 36) = 32.93, p < .001, and SNR, F(4, 48) = 23.43, p < .001. Effects were significant for RT across the sound booth condition and the closest classroom condition of 0.3-s RT, F(1, 12) = 10.51, p = .007, and for SNR, F(4, 48) = 16.75, p < .001. There were no significant interactions between RT and SNR in these analyses. Within each SNR from +9 to +21 dB, the subgroup scored an average 9.8 percentage points higher in the booth than in the closest classroom RT, 0.3 s.
The analysis of variance of RT–SNR scores by children with cochlear implants were constrained to SNRs from +9 to +21 dB to focus on the effects of classroom acoustics on scores approaching 50% and higher. Scores below this point were considered too low for the purposes of this study. This range also reduced the number of participants with missing data points to three or fewer and avoided apparent floor effects at low SNRs. Among the group with cochlear implants, participant No. 23 (see Table 1) required a start SNR of +18 dB; participants Nos. 1, 3, 5, 7, 8, 9, 12, 14, 15, 17, and 20 required +21 dB SNR; Nos. 2, 4, 6, 11, 13, 16, 18, 19, 21, and 22 required +24 dB SNR; and No. 10 required +27 dB SNR.
RT–SNR Scores for Participants with Typical Hearing
The main effect of classroom RT on speech perception scores for participants with typical hearing (N = 23) was significant, F(2, 44) = 10.35, p < .001. The main effect of SNR was also significant, F(4, 88) = 88.99, p < .001. Scores differed significantly between 0.9- and 0.6-s RT, F(1, 22) = 12.54, p = .001, and across SNRs, F(4, 88) = 79.43, p < .001. The interactions between effects in both analyses were significant. When analysis of scores from 0.9- to 0.6-s RT included only −3 to +6 dB SNR, however, the RT and SNR interaction was nonsignificant, suggesting that the interaction was due to the convergence of scores at +9 dB SNR in these two RT conditions. The effect of RT between 0.6 and 0.3 s RT was nonsignificant, F(1, 22) = 0.00, p = .997, whereas the effect of SNR was significant, F(4, 88) = 73.72, p < .001. The interaction between effects was nonsignificant. Scores plotted as performance-intensity functions by RT and SNR are in Figure 3. Mean, standard deviation, and N for scores from −6 to +15 dB SNR are provided in the online supplemental materials, Supplemental Table S3.
Scores improved significantly in post hoc analyses with a change from 0.9- to 0.6-s RT when combined with each 3-dB increase in SNR from −3 to +9 dB, all p ≤ .031. Scores improved significantly when RT shortened from 0.6- to 0.3-s RT and combined with each 3-dB increase in SNR from −3 to +6 dB, all p ≤ .016, and improved nonsignificantly when SNR increased from +6 to +9 dB, p = .389.
For the subgroup with typical hearing (n = 8) tested in both the sound booth and classroom, the main effect of RT across all four RTs was nonsignificant, F(3, 21) = 1.99, p = .145, the main effect of SNR was significant, F(4, 48) = 39.00, p < .001, and the interaction of effects was significant. The effect of RT between the sound booth condition and the closest condition in the classroom, 0.3-s RT, was nonsignificant, F(1, 7) = 0.16, p = .693, whereas the effect of SNR was significant, F(4, 28) = 56.94, p < .001, with no significant interaction of effects.
The statistical analyses of performance by children with typical hearing were constrained to SNRs from −3 to +9 dB to focus on the effects of reverberation on scores approaching 50% or higher. Scores below this were considered to offer potential insights outside the scope of this study. This range also reduced the number of missing data points and avoided what appeared to be emerging floor effects below −3 dB and ceiling effects above +9 dB SNR. Five participants required a start SNR of +9 dB, eight required +12 dB SNR, seven required +15 dB, and three required +18 dB SNR.
Age and SNR-50 Scores
There was no correlation for the group with cochlear implants between age and any of the mean SNR-50 scores in the three classroom RTs (correlation of age to SNR-50 in 0.3-, 0.6-, and 0.9-s RT: r = .284, .135, and .245, respectively; all p ≥ .188). For the group with typical hearing, there were significant negative correlations between age and SNR-50 scores within each of the three classroom RTs (correlation of age to SNR-50 in 0.3-, 0.6-, and 0.9-s RT: r = −.552, −.566, and −.614, respectively; all p ≤ .001) when including the three participants age <7 years in the group analyses. The intent of the study was to investigate the acoustical needs of children across a broad range of school ages. The analysis, therefore, included this relatively small number (three) of participants with typical hearing and age <7 years.
Discussion
1. Are the differences significant in speech perception ability between children with cochlear implants and those with typical hearing when listening in the same classroom and sound booth RTs?
The children with cochlear implants compared to those with typical hearing performed significantly poorer in SNR-50 scores by more than 10 dB in each classroom RT and by 7.9 dB SNR in the sound booth (see Figure 2 and the online supplemental materials, Supplemental Table S2). For example, in +9 dB SNR, the children with cochlear implants scored 42.1 percentage points lower in 0.3-s RT, and the subgroup scored 22.5 percentage points lower in the booth than those with typical hearing (see Figure 3 and the online supplemental materials, Supplemental Table S3). The performance gap closed only in high SNRs in the shortest classroom RT as well as in the sound booth, supporting the findings of others (Finitzo-Hieber & Tillman, 1978) that children with hearing loss benefit from both low RTs and high SNRs. The children with cochlear implants required SNRs above +15 dB recommended by the American Speech-Language-Hearing Association (2016)  for perception of speech by students with typical hearing.
Neuman et al. (2010)  reported that children with typical hearing scored higher (poorer) SNR-50 scores in 0.6-s RT than that measured in the current study in the same RT. Neuman et al. (2010), as a result, found smaller performance differences between children with typical hearing and those with cochlear implants (Neuman et al., 2012) compared to this study. Neuman et al. (2010)  presented speech prerecorded in 0.6-s RT binaurally through earphones to the children with typical hearing and, in Neuman et al. (2012), as electro-acoustical input to the processors for those with implants, most bilaterally fitted, as compared to listening in a classroom in this study. Possibly the listeners with typical hearing in Neuman et al. (2010)  may have lost acoustic details otherwise perceptible in the room environment of this study with spatial separation of speech and noise sources and potential head shadow. Neuman et al. (2012)  did not report on acoustic features potentially lost in the acoustical input to processors for those with cochlear implants.
2. Are the RT requirements in the ANSI/ASA (2010)  classroom acoustic standards suitable for both children with cochlear implants and those with typical hearing?
Each reduction in RT for 0.9 to 0.6 to 0.3 s significantly benefited speech perception in the children with cochlear implants when measured both as SNR-50 scores and by RT–SNR scores. Reduction in RT from 0.9 to 0.6 s significantly benefited the children with typical hearing, whereas the reduction to 0.3 s was of no harm or further benefit. These findings support the standards described in ANSI/ASA S12.60-2010/Part 1, which require that classroom reverberation must not exceed 6-s RT (core learning spaces ≤283 m3; see ANSI/ASA table 1); “learning spaces shall be readily adaptable to allow reduction in reverberation time to 0.3 s” (see ANSI/ASA table 1, footnote e); and “a reverberation time of 0.3 s … is necessary for children with hearing impairment and/or other communicative issues” (Commentary-5.3.1).
3. Do speech perception scores obtained in a nonreverberant sound booth differ significantly from scores obtained in a classroom with a relatively low RT?
The subgroup of children with cochlear implants performed significantly poorer in the shortest classroom RT of 0.3 s compared to the sound booth. Their SNR-50 score in 0.3-s RT was 2.2 dB higher (poorer) than in the booth (see the online supplemental materials, Supplemental Table S2), and RT–SNR scores from +9 to +21 dB SNR averaged 9.8 percentage points lower. Standard deviations in scores suggest caution in applying these averages to any one child.
Differences in SNR-50 scores between booth and classroom conditions were nonsignificant for the subgroup with typical hearing. Others, however, have found significant score differences: between 0.0- and 1.2-s RT by Finitzo-Hieber and Tillman (1978), and between 0.0- and 0.8-s RT by Yacullo and Hawkins (1987) . Those two studies, however, permitted only monaural listening. This study allowed binaural listening, which benefits speech perception in reverberation (Nabelek & Pickett, 1974) and may reduce perceptual challenges of reverberant environments. The lack of significant difference in this study between these conditions also may have been due to a small subsample number used in the analyses. The lack of spatial separation of speech and noise speakers in the booth may have eliminated potential listening benefits to listeners with typical hearing and possibly those with bilateral implants that were available in the classroom.
Neuman et al. (2012)  and this study used two of the same RTs with children with cochlear implants and both also used the BKB-SIN test. Neuman et al. (2012)  reported mean SNR-50 scores for these children of 10.2 dB in 0.6-s RT and 5.8 dB in a nonreverberant condition. Similarly in this study, the SNR-50 scores for the subgroup of children with implants were 10.7 dB in 0.6-s RT and 7.4 dB in the sound booth.
A related issue may arise with the use of 0.3-s RT for children with hearing loss when children with typical hearing are also present in the classroom. Early sound reflections (<50 ms) have been reported to benefit the perception of speech (e.g., Bradley, Sato, & Picard, 2003; Lochner & Burger, 1964; Yang & Bradley, 2009), and shortening RTs may potentially reduce these early reflections significantly enough to affect listening. Measurements of these early reflections in classrooms and their effects on speech perception in children, however, do not appear to have been published to date. Reductions in this study and others to 0.0 s (Finitzo-Hieber & Tillman, 1978) or to 0.3 s (Neuman et al., 2010) caused no significant change in scores in children with typical hearing.
This study used the BKB-SIN test because multitalker babble may better represent classroom noise compared to speech-shaped noise, it uses a range of SNRs common to, or better than, most classrooms, and the test has a sufficient quantity of sentence lists to cover all test conditions without repetition. The BKB-SIN test, however, presents each sentence list in SNRs progressing only from high to low values. Anecdotal observations outside the study suggest this progression may cause some listeners to prematurely give up as a list becomes increasingly difficult, which may yield lower scores compared to a test with adaptive procedures (e.g., HINT-C; Nilsson, Soli, & Gelnett, 1996). In addition, future studies including the beneficial effects of speech reading and other visual cues may likely yield a more complete understanding of speech perception in the classroom. Another issue is whether children with or without hearing loss exert greater listening effort as RT increases, which may add cognitive load in understanding the teacher and peers.
The study modified the BKB-SIN in several nonvalidated ways. The SNR-50 is the only validated score in the BKB-SIN test, whereas scoring by SNR in the BKB-SIN test and the resultant performance-intensity functions used in this study and others (Neuman et al., 2010; Wilson, McArdle, & Smith, 2007) have not been validated. Also in this study, the score for each RT–SNR combination was based on only four to six target words per participant. The BKB-SIN also was validated with lists of eight and 10 sentences. Equalizing lists in this study to eight sentences in length has not been validated. As described by M. Skinner (personal communication, December 10, 2006), however, Sentences 9–10 in the longer lists are presented under the poorest SNRs, which would result in scores near 0%, and their removal would likely have no significant effect on test scores. These two last sentences also could have potentially discouraged some children with hearing loss and thus reduced validity and reliability.
The BKB-SIN was also validated only with a start SNR of +21 dB. At the time of data collection, however, there were no published data for the BKB-SIN test to suggest a single start SNR for listening in reverberation for any group of listeners. Anecdotal evidence with children with typical hearing suggested that the start SNR of +21 dB would produce extended ceiling effects and not reveal the full range of the group's listening ability. A start SNR of +21 dB for children with cochlear implants would lead to extended floor effects and failure to capture many individuals' optimal performances. The use of adaptive start SNRs helped avoid these anticipated effects on calculations of scores, but a downside was that the same 21-dB range would not apply across all participants. This would result in within-group missing data at some SNRs and thus reduced N for some analyses. The BKB-SIN also has been validated for use with noise but not with noise and reverberation. The results of the study should be interpreted with caution in light of these changes to the validated use of the BKB-SIN test.
Picard and Bradley (2001)  reviewed several studies of teachers' voice levels in the classroom and calculated a mean speech level of 60.1 dBA, with a range of 56.9– 69.6 dBA. The adaptive speech presentation levels from 60 to 66 dBA for the children with cochlear implants in this study remained within these measured speech levels. This adaptive approach, however, introduced variation in test conditions, and in light of this variation the results should be interpreted with caution. In addition, testing the youngest children with fewer test items may have increased statistical variability compared to the older group (Etymotic Research, Inc., 2005). The use of two list pairs, however, may likely have decreased variability over the use of one list pair as suggested in the BKB-SIN test manual for routine clinical testing.
The use of 50 acoustic panels to reduce RT in the study's classroom to 0.3 s may not be practical for many classrooms. The test classroom, however, lacked acoustic ceiling tiles and an untreated RT of 0.9 s. Several other similarly sized classrooms in the host school had acoustic ceiling tiles combined with a limited number of acoustic wall panels located conveniently between black/white boards, banks of windows, and large wall displays, with RTs measuring close to 0.3 s. This relatively short RT may likely be readily attainable in other classrooms and without interference in room function.
Several aspects of the test conditions did not represent a classroom of children. The listening position was always both close (3.0 m) to the speech source and unchanged. The test classroom also was unoccupied with noise of consistent spectrum and specific levels, coming equally from all directions, and with consistent RTs. One or more of these acoustic factors would often change in a classroom of children.
Cochlear implant technology can help improve speech perception in challenging acoustic conditions through the use of directional microphones and FM systems (e.g., Schafer & Thibodeau, 2006). FM systems can help improve speech perception in noise and likely reduce the detrimental effects of reverberation by reducing the functional distance between talker and listener to well within the critical distance in any classroom. Some limitations, however, are FM access only to the talker with the microphone, and FM reliability as an electronic system undergoing wear and tear from the children who use it.
Reductions in classroom RTs to 0.3 s significantly benefited speech perception in children with cochlear implants, whereas reduction to 0.6-s RT benefited children with typical hearing. Furthermore, 0.3-s RT was not detrimental to those with typical hearing. These findings are in agreement with the ANSI/ASA S12.60-2010/Part 1 standards for acoustics in learning spaces (≤283 m3). The children with cochlear implants performed significantly better in an audiology sound booth than the least reverberant condition in the classroom. This finding suggests that clinical results obtained in a nonreverberant test environment may likely overestimate speech perception abilities of children with cochlear implants in the classroom.
Acknowledgments
This research was supported by the National Institute on Disability and Rehabilitation Research Grant H133G060116 and grants from the Gustuvus and Louise Pfeiffer Research Foundation, awarded to Frank Iglehart. The author thanks Arthur Boothroyd, John Bradley, Richard Freyman, and Margaret Skinner for comments and suggestions throughout this project, and the participants and their families for their time and cooperation. Preliminary reports on segments of this study were presented at the 19th International Congress on Acoustics, Madrid, Spain; Acoustics '08 – Joint Conference of the Acoustical Society of America and the European Acoustics Association, Paris, France; Inter•Noise 2009 – The 38th International Congress and Exposition on Noise Control Engineering, Ottawa, Canada; and EURONOISE 2009 – Action on Noise in Europe, Edinburgh, Scotland.
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Figure 1.

The arrangement of the classroom with the student located near the center of the room, seated at a desk; two adult scorers were seated to the right and left. The speech loudspeaker was 0° azimuth to the student, with four noise loudspeakers, one facing each corner. The room also contained an alcove and several floor and wall cabinets.

 The arrangement of the classroom with the student located near the center of the room, seated at a desk; two adult scorers were seated to the right and left. The speech loudspeaker was 0° azimuth to the student, with four noise loudspeakers, one facing each corner. The room also contained an alcove and several floor and wall cabinets.
Figure 1.

The arrangement of the classroom with the student located near the center of the room, seated at a desk; two adult scorers were seated to the right and left. The speech loudspeaker was 0° azimuth to the student, with four noise loudspeakers, one facing each corner. The room also contained an alcove and several floor and wall cabinets.

×
Figure 2.

Calculated speech-to-noise ratios (SNRs) for SNR-50 in children with cochlear implants (CI) and children with typical hearing (TH) in three classroom reverberation times (RTs) and subgroups of these children in the sound booth (SB). Error bars represent standard errors.

 Calculated speech-to-noise ratios (SNRs) for SNR-50 in children with cochlear implants (CI) and children with typical hearing (TH) in three classroom reverberation times (RTs) and subgroups of these children in the sound booth (SB). Error bars represent standard errors.
Figure 2.

Calculated speech-to-noise ratios (SNRs) for SNR-50 in children with cochlear implants (CI) and children with typical hearing (TH) in three classroom reverberation times (RTs) and subgroups of these children in the sound booth (SB). Error bars represent standard errors.

×
Figure 3.

Mean scores plotted as performance/intensity curves by reverberation time (RT) and speech-to-noise ratio for children with cochlear implants (CI) and children with typical hearing (TH) when listening in the classroom. Error bars represent standard errors.

 Mean scores plotted as performance/intensity curves by reverberation time (RT) and speech-to-noise ratio for children with cochlear implants (CI) and children with typical hearing (TH) when listening in the classroom. Error bars represent standard errors.
Figure 3.

Mean scores plotted as performance/intensity curves by reverberation time (RT) and speech-to-noise ratio for children with cochlear implants (CI) and children with typical hearing (TH) when listening in the classroom. Error bars represent standard errors.

×
Table 1. Background information on participants with cochlear implants.
Background information on participants with cochlear implants.×
Participants
Implanted device
Processor Age at implantation
Cause of hearing loss
No. Age (Years) Gender Right ear Left ear Right Left
1 5.8 F Nucleus 24 Freedom Freedom 1.0 3.5 Connexin 26 mutation
2 7.0 F Freedom Unaided Freedom 2.9 Meningitis
3 7.0 F Nucleus 24 Nucleus 24 Freedom 6.5 5.4 Unknown
4 7.5 M HiRes 90K Unaided Harmony 2.4 Unknown
5 8.3 M Nucleus 24 Freedom Freedom 1.5 6.3 Connexin 26 mutation
6 8.7 F Harmony 3.6 7.6 Pendred's syndrome
7 8.8 M Nucleus 24 Freedom Freedom 2.3 7.8 Connexin 26 mutation
8 9.7 M Nucleus 24 Freedom Freedom 6.4 4.0 Unknown
9 10.8 F Unaided Nucleus 24 Freedom 5.0 Genetic
10 10.8 M Unaided Freedom 3.9 Unknown
11 10.8 F Freedom Unaided Freedom 8.4 Unknown
12 11.0 M Freedom 2.4 10.7 Cytomegalo virus
13 11.5 F Unaided Nucleus 24 Freedom 2.5 Connexin 26 mutation
14 11.5 F Nucleus 24 Freedom Freedom 8.8 2.8 Unknown
15 12.4 M Unaided ESPrit 3G 3.8 Suspected genetic
16 12.5 F HiRes 90K C II Auria 10.9 7.3 Unknown
17 12.7 F Nucleus 24 Unaided ESPrit 3G 3.7 Unknown
18 12.8 M C II HiRes 90K Harmony 5.5 11.5 Unknown
19 13.0 M Freedom Freedom Freedom 2.8 12.9 Unknown
20 15.7 M Nucleus 24 Unaided ESPit 3G 2.4 Cochlear malformation
21 15.8 M C I Unaided Platinum BTE 5.3 Meningitis
22 15.9 M HiRes 90K HiRes 90K Harmony 4.4 13.9 Unknown
23 16.0 M Unaided Freedom Freedom 14.3 Unknown
Note. Unaided = no implant or hearing aid; — = information not available. A small number of students required re-implantation; ages provided are for first implantation, whereas the model of implant device was in use at time of testing. All bilateral users were implanted sequentially and wore the same model processor on both ears.
Note. Unaided = no implant or hearing aid; — = information not available. A small number of students required re-implantation; ages provided are for first implantation, whereas the model of implant device was in use at time of testing. All bilateral users were implanted sequentially and wore the same model processor on both ears.×
Table 1. Background information on participants with cochlear implants.
Background information on participants with cochlear implants.×
Participants
Implanted device
Processor Age at implantation
Cause of hearing loss
No. Age (Years) Gender Right ear Left ear Right Left
1 5.8 F Nucleus 24 Freedom Freedom 1.0 3.5 Connexin 26 mutation
2 7.0 F Freedom Unaided Freedom 2.9 Meningitis
3 7.0 F Nucleus 24 Nucleus 24 Freedom 6.5 5.4 Unknown
4 7.5 M HiRes 90K Unaided Harmony 2.4 Unknown
5 8.3 M Nucleus 24 Freedom Freedom 1.5 6.3 Connexin 26 mutation
6 8.7 F Harmony 3.6 7.6 Pendred's syndrome
7 8.8 M Nucleus 24 Freedom Freedom 2.3 7.8 Connexin 26 mutation
8 9.7 M Nucleus 24 Freedom Freedom 6.4 4.0 Unknown
9 10.8 F Unaided Nucleus 24 Freedom 5.0 Genetic
10 10.8 M Unaided Freedom 3.9 Unknown
11 10.8 F Freedom Unaided Freedom 8.4 Unknown
12 11.0 M Freedom 2.4 10.7 Cytomegalo virus
13 11.5 F Unaided Nucleus 24 Freedom 2.5 Connexin 26 mutation
14 11.5 F Nucleus 24 Freedom Freedom 8.8 2.8 Unknown
15 12.4 M Unaided ESPrit 3G 3.8 Suspected genetic
16 12.5 F HiRes 90K C II Auria 10.9 7.3 Unknown
17 12.7 F Nucleus 24 Unaided ESPrit 3G 3.7 Unknown
18 12.8 M C II HiRes 90K Harmony 5.5 11.5 Unknown
19 13.0 M Freedom Freedom Freedom 2.8 12.9 Unknown
20 15.7 M Nucleus 24 Unaided ESPit 3G 2.4 Cochlear malformation
21 15.8 M C I Unaided Platinum BTE 5.3 Meningitis
22 15.9 M HiRes 90K HiRes 90K Harmony 4.4 13.9 Unknown
23 16.0 M Unaided Freedom Freedom 14.3 Unknown
Note. Unaided = no implant or hearing aid; — = information not available. A small number of students required re-implantation; ages provided are for first implantation, whereas the model of implant device was in use at time of testing. All bilateral users were implanted sequentially and wore the same model processor on both ears.
Note. Unaided = no implant or hearing aid; — = information not available. A small number of students required re-implantation; ages provided are for first implantation, whereas the model of implant device was in use at time of testing. All bilateral users were implanted sequentially and wore the same model processor on both ears.×
×
Table 2. Mean ages and durations of implant use for children with unilateral versus bilateral cochlear implant fittings.
Mean ages and durations of implant use for children with unilateral versus bilateral cochlear implant fittings.×
Years Range
Unilateral fittings (N = 11)
Age at testing 11.9 7.0–16.0
(10.7) (7.0–15.7)
Age at implant 4.9 2.4–14.3
(4.0) (2.5–8.4)
Duration of use 6.1 1.7–13.3
(6.8) (2.4–13.3)
Bilateral fittings (N = 12)
Age at testing 10.4 5.8–15.9
(10.9) (7.0–15.9)
Age at first implant 3.6 1.0–7.3
(3.8) (1.5–5.5)
Duration of first implant use 6.8 1.6–11.5
(7.1) (1.6–11.5)
Age at second implant 8.9 3.5–13.9
(9.3) (6.3–13.9)
Duration of second implant use 1.5 0.1–3.3
(1.6) (0.1–3.3)
Note. Data on the subsets of five unilaterally and eight bilaterally fitted children tested in both sound booth and classroom are in parentheses.
Note. Data on the subsets of five unilaterally and eight bilaterally fitted children tested in both sound booth and classroom are in parentheses.×
Table 2. Mean ages and durations of implant use for children with unilateral versus bilateral cochlear implant fittings.
Mean ages and durations of implant use for children with unilateral versus bilateral cochlear implant fittings.×
Years Range
Unilateral fittings (N = 11)
Age at testing 11.9 7.0–16.0
(10.7) (7.0–15.7)
Age at implant 4.9 2.4–14.3
(4.0) (2.5–8.4)
Duration of use 6.1 1.7–13.3
(6.8) (2.4–13.3)
Bilateral fittings (N = 12)
Age at testing 10.4 5.8–15.9
(10.9) (7.0–15.9)
Age at first implant 3.6 1.0–7.3
(3.8) (1.5–5.5)
Duration of first implant use 6.8 1.6–11.5
(7.1) (1.6–11.5)
Age at second implant 8.9 3.5–13.9
(9.3) (6.3–13.9)
Duration of second implant use 1.5 0.1–3.3
(1.6) (0.1–3.3)
Note. Data on the subsets of five unilaterally and eight bilaterally fitted children tested in both sound booth and classroom are in parentheses.
Note. Data on the subsets of five unilaterally and eight bilaterally fitted children tested in both sound booth and classroom are in parentheses.×
×
Table 3. Changes in speech and noise levels resulting from changes in reverberation time.
Changes in speech and noise levels resulting from changes in reverberation time.×
RT Speech Noise Change in RT Speech Noise SNR a
0.9 60.8 61.3 change to 0.6 −1.3 −1.7 +0.4
0.6 59.5 59.6 change to 0.3 −1.3 −4.0 +2.7
0.3 58.2 55.6 change to 0.9 +2.6 +5.7 −3.1
Note. RT = reverberation time (s); SNR = speech-to-noise ratio (dBA)
Note. RT = reverberation time (s); SNR = speech-to-noise ratio (dBA)×
a These net changes in SNR with each change of RT were removed by adjustments in noise levels, thereby keeping SNRs constant across changes in RT.
These net changes in SNR with each change of RT were removed by adjustments in noise levels, thereby keeping SNRs constant across changes in RT.×
Table 3. Changes in speech and noise levels resulting from changes in reverberation time.
Changes in speech and noise levels resulting from changes in reverberation time.×
RT Speech Noise Change in RT Speech Noise SNR a
0.9 60.8 61.3 change to 0.6 −1.3 −1.7 +0.4
0.6 59.5 59.6 change to 0.3 −1.3 −4.0 +2.7
0.3 58.2 55.6 change to 0.9 +2.6 +5.7 −3.1
Note. RT = reverberation time (s); SNR = speech-to-noise ratio (dBA)
Note. RT = reverberation time (s); SNR = speech-to-noise ratio (dBA)×
a These net changes in SNR with each change of RT were removed by adjustments in noise levels, thereby keeping SNRs constant across changes in RT.
These net changes in SNR with each change of RT were removed by adjustments in noise levels, thereby keeping SNRs constant across changes in RT.×
×
Supplemental Table S1.Reverberation times for each classroom condition
Supplemental Table S2.Speech-to-noise ratios for 50% correct perception of speech (SNR-50) by reverberation time
Supplemental Table S3.Speech perception scores (% correct) for each listening condition