University of Edinburgh

Improving the Listening Environment for Deaf Children in Educational Settings

Presented on Tuesday 13 May 2010

Dr Laurent Galbrun
School of the Built Environment
Heriot-Watt University, Edinburgh

Workshop 3 Listening to speech recorded in different teaching spaces

The aim of this workshop is to develop an awareness of how background noise,
reverberation time and distance between speaker and listener all affect speech intelligibility.

This is done by listening critically to speech recorded in two different teaching spaces.

Participants will listen to speech recorded at a variety of positions in two teaching spaces. The spaces selected will be representative of bad and good acoustic conditions.

Results will be presented with background noise data, reverberation time data and speech intelligibility data.

The figure below shows how the sound pressure level (SPL) changes with the source-receiver distance: close to the source the direct field is dominant, while far from the source the reverberant field is dominant.

Figure 3.1 Sound pressure level as a function of the distance between the source and
receiver. At a certain distance (r*) the reverberant field becomes dominant.


In rooms with low absorption, the critical distance r* is small: the reverberant field is
dominant in most of the space and sitting in the first or last row of a classroom is not much different! However this is not true for rooms having very high absorption values.