Large Area Assistive Listening Systems: Review and Recommendations

8.1 Objective

The objective of this study was to establish guidelines for specifying the acceptable output characteristics of assistive listening devices for people with hearing loss. Fifty-nine adult listeners (49 with hearing loss and 10 without) listened binaurally to sentence materials that were subjected to three different types of distortion; reverberation and background noise, internally-generated induction loop noise, and peak clipping. The listeners provided ratings as to the quality of the materials presented. A minimally acceptable criterion was selected and results for the listeners with hearing loss were compared with that criterion to arrive at:

1. Minimally acceptable output and dynamic range levels,

2. Minimally acceptable Speech Transmission Index (STI) level,

3. Minimally acceptable signal-to-noise ratio for internally generated noise, and

4. Minimally acceptable peak clipping level.