Room Modes With Regard to Speech Intelligibility in Classrooms: Comments on Knecht et al. (2002) Purpose To comment on the article “Background Noise Levels and Reverberation Times in Unoccupied Classrooms: Predictions and Measurements” by Knecht, Nelson, Whitelaw, and Feth (2002) . Method Schroeder frequencies to determine the transition from individual resonances to many overlapping normal modes are calculated and discussed. Results Schroeder ... Letter to the Editor
Letter to the Editor  |   December 01, 2010
Room Modes With Regard to Speech Intelligibility in Classrooms: Comments on Knecht et al. (2002)
 
Author Affiliations & Notes
  • P. Jafari Shalkouhi
    Science and Research Branch, Islamic Azad University, Tehran, Iran
  • Contact author: P. Jafari Shalkouhi, Department of Environmental Engineering, Graduate School of the Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran. E-mail: pedram121212@yahoo.com.
Article Information
Speech, Voice & Prosodic Disorders / School-Based Settings / Letters to the Editor
Letter to the Editor   |   December 01, 2010
Room Modes With Regard to Speech Intelligibility in Classrooms: Comments on Knecht et al. (2002)
American Journal of Audiology, December 2010, Vol. 19, 139-141. doi:10.1044/1059-0889(2010/09-0023)
History: Received August 11, 2009 , Revised November 15, 2009 , Accepted January 3, 2010
 
American Journal of Audiology, December 2010, Vol. 19, 139-141. doi:10.1044/1059-0889(2010/09-0023)
History: Received August 11, 2009; Revised November 15, 2009; Accepted January 3, 2010
Web of Science® Times Cited: 1

Purpose To comment on the article “Background Noise Levels and Reverberation Times in Unoccupied Classrooms: Predictions and Measurements” by Knecht, Nelson, Whitelaw, and Feth (2002) .

Method Schroeder frequencies to determine the transition from individual resonances to many overlapping normal modes are calculated and discussed.

Results Schroeder frequencies ranged from 67 Hz to 141 Hz.

Conclusions Knecht et al. could have validly measured reverberation time at 250 Hz in all classrooms and at 125 Hz in the majority of classrooms because, above the Schroeder frequency, measurement of reverberation time is not significantly affected by room modes. Furthermore, Knecht et al. selected 5 different positions in each classroom for measurement of reverberation time, but in small volumes more measurement positions must be selected due to the effects of room modes compared with large volumes.

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