The advent of hearing aids which are inserted directly into the user's ear canal has highlighted the problem of ear wax (cerumen) build up. Cerumen produced in the ear canal can damage hearing aids in several ways. Firstly, the wax can build up in the sound spout of the hearing aid and reduce the sound output by a significant amount. When cerumen totally blocks the sound spout the sound output is nil and the hearing aid appears dead.
Secondly, cerumen may migrate through the sound spout and into the hearing aid receiver thereby causing irreparable damage to the transducer and necessitating extensive repair work.
In addition, wax accumulation presents a problem even if the sound spout is only partly blocked because removing the wax from the hearing aid during cleaning may result in wax inadvertently falling down the sound spout into the receiver port.
As a result of the wax build-up and migration problem, various attempts have been made to delay the progress of the wax into the sound spout and receiver port of the hearing aid. Such attempts are shown, for example, in U.S. Pat. No. 4,553,627 filed Oct. 22, 1984, European Patent Application No. 0287315 filed Dec. 4, 1988, and U.K. Patent Application GB2155276A filed Jun. 18, 1984. The above patents show various approaches which have been taken to provide a wax guard for the sound spout of a hearing aid. However these proposals have had only limited success in delaying the progress of wax into the sound spout and receiver port or the hearing aid. The ease of removal and cleaning of the guard is very important given the advanced age of many hearing aid users.