Abstract
This paper presents an investigation relating to the CROS hearing aid system. Eight adults with severe or total unilateral sensorineural hearing impairment took part in a series of experiments with a view to comparing their speech discrimination in noise and localisation abilities achieved both with and without two different types of CROS hearing aids. The first type of CROS aid involved an acoustic head loop and the second type was the classical CROS as described by Harford and Barry (1965). Testing was carried out in a non-reverberant environment. With regard to speech discrimination in noise it was found that the CROS aids, in situations whereby speech was coming from the side of the good ear and noise from the side of the affected ear, had a deleterious effect in the order of 13 dB S/N ratio calculated at the 50% discrimination level. When the listening situation was reversed, however, (speech from the side of the affected ear and noise from the side of the good ear) the CROS aids enhanced speech discrimination in the order of 5 dB S/N ratio. The CROS aids in this investigation were found to interfere with localisation ability. The results achieved with both types of CROS aids were remarkably similar. It is concluded that the CROS aid system when selectively used provides benefits in terms of speech discrimination enhancement to people with severe/total unilateral hearing impairment.