6.10 Assistive Listening Systems
6.10.1 The hearing problem
A hearing-impaired person has to hear the signal, with or without hearing aids, in order to understand it and loudness is just one part of the listening equation. For most people with hearing loss, the comprehension of verbal messages takes more than audibility. Their comprehension also depends upon the nature of their hearing losses.

The most common problem in hearing which affects older persons in particular is that hearing acuity is poorer at the higher frequencies than at the lower ones. The acoustic characteristics of speech that allow listeners to distinguish between speech sounds occur largely in the higher frequencies. The common complaint of people with hearing loss is that they can "hear" the low frequency components of speech signals and know someone is talking, but they cannot "understand" because many of the important higher frequencies are filtered out by their hearing loss.

The sound signals which traverse acoustical space before arriving at a listener are weakened by proportion to the travel distance and distorted by background noise reverberation and other acoustical conditions before reaching the listeners. The situation will not be improved just by increasing loudness.

The approach is to take appropriate steps so that communications with people with disabilities are as effective as with the general public.

Assistive listening systems are useful for effective communication with the hearing impaired (6.10.1a). With such auxiliary aids, a hearing impaired person can enjoy equal opportunity to the benefits of an activity, a service, or a programme.
User requirements are the prime consideration in determining what type of assistive listening system would be appropriate for a venue.