A very impressive and authoritative site. The most common frequency for FM is 72.9MHz. FM and IR are not interchangeable, i.e., the system established by the facility determines what type of receiver you must use. A certain number of receivers are usually available at no cost during a performance. No longer will you have to miss punch lines, stage whispers, or soft speech and, as a rule, you will not be troubled by background or other ambient noise.
Restaurants present a special problem because of the almost constant and loud background noise.
The catalogs available spell out the various types of ALDs which work well in that environment. Most of them make use of some type of microphone arranged to bring out only very nearby voices. Other venues such as funeral home chapels seldom provide any of the ADA-mandated services and simply rely on standard PA equipment. In this document I am concentrating only on those public auditoriums, churches, and theaters that we all attend from time to time. What this ALD does, as far as I can determine, is to amplify nearby voices more than it does distant voices.