A New High-Efficiency Earmould

Abstract

The problems associated with earmoulds currently used by hearing-impaired persons, particularly children, are outlined. A new type of earmould which combines high efficiency with minimal feedback is described and evaluated.

Improving on What is Possible with Hearing Aids for Listening to Music

“…(v) Harmonic distortion is considered acceptable in hearing aids if the total does not exceed 10%. 3 By contrast, the audio system described here could have less than 05 % total harmonic distortion (including that of the loudspeakers or headphones).…”

“…If loudspeakers are used they must be of adequate size: a true bass response, not an acoustic bass, is most important. 6 The procedure for setting up the graphic equaliser, using the chosen headphones, is as follows. This procedure is also used with equalisation for cases of sensory-neural hearing loss.…”

“…Similarly a harpsichord sound can be synthesised without the sound of the jacks striking the strings or without the mechanical noise caused by the movement of the action. 6 In a pipe organ a substantial part of the total sound energy is noise produced by the air which blows the pipe and by other factors; and in an electronic organ, if no attempt is made to synthesise this noise, people with good hearing are likely to complain that the instrument sounds ' very electronic'.…”

“…By comparison, settings for hearing aids might be 18 and 180 msec. 6 Other settings on the compressor might be a compression ratio of 4 and a medium value for the threshold level at which compression is to begin. The threshold would be adjusted so that compression does not operate on the quieter passages of the music.…”

“…This is being done in three ways: (1) by processing the sound to make the best use of available hearing; (2) by providing a colour graphic visual display which is designed to be an analogue of the music, phrase by phrase; and (3) by providing a representation of the music in vitro-tactile form. (2) and (3) are intended for use when there is little hearing, but even then they are used in conjunction with processed sound. In other words, where necessary, the information is being additionally transmitted to the brain in a way which bypasses the ears, but in all cases the ears are being used to the maximum extent possible.…”