Self-noise problems in hearing aids

A study has been carried out to determine the extent to which the self-noise of a hearing aid constitutes a problem for aid users. A survey of hearing aid users was carried out followed by a laboratory study. None of the 75 hearing aid users seen during the survey complained of being troubled by self-noise and none of the subjects investigated at the Institute of Sound and Vibration Research was able to hear any self-noise at normal aid settings when listened for in a sound proofed room. Tests confirmed that aid noise becomes audible only when the noise level in any 1/3 octave band rises above the threshold for a pure tone at the centre of that band, and typical equivalent input noise levels indicate that audible self-noise is caused by gain being applied over a frequency band where the aid user has negligible or no hearing loss, as is likely in the case of persons with 'ski-slope' hearing loss. It is suggested that anyone else complaining of problems with self-noise is probably mistaking external background noise for self-noise of the aid.