Assistive Listening Systems Bulletin 9B : For Installers

By United States Access Board

Book Id: WPLBN0000703186
Format Type: PDF eBook:
File Size: 0.3 MB
Reproduction Date: 2005

Title:	Assistive Listening Systems Bulletin 9B : For Installers
Author:	United States Access Board
Volume:
Language:	English
Subject:	Government publications, Access Board, Architectural and Transportation Barriers Compliance Board
Collections:	Government Library Collection, U.S. Access Board Collection
Historic Publication Date:
Publisher:	United States Access Board


Citation APA MLA Chicago States Access Board, B. U. (n.d.). Assistive Listening Systems Bulletin 9B : For Installers. Retrieved from http://gutenberg.cc/

Description
Government Reference Publication

Excerpt
Excerpt: How do assistive listening systems (ALS) interface with public address (PA) systems? Public address systems are, in fact, assistive listening systems. They are designed to help people hear across a distance. In a PA system, the sound is picked up at a microphone and delivered through speakers that bring the amplified sound closer to listeners in an audience. For many people and in many circumstances, a loudspeaker may provide enough gain in volume for adequate speech perception. But no matter how well-placed the loudspeaker(s), perception of air-borne speech signals will be difficult for people with hearing loss unless background noise and reverberation can be carefully controlled. The same microphone pick-up used in the PA system can also serve an assistive listening system (ALS or ALD). By bridging the acoustical space between the source and the listener, an ALS circumvents the effects of distance (drop in volume), background noise (competing sound), and reverberation (reflecting sound that blurs the desired signal).