Factors to consider when in-the-canal hearing instruments are used in aural rehabilitation.

The purpose of this investigation was to determine what subjective factors may influence the success of fitting in-the-canal hearing instruments (ITCs). Four different types of ITC were fitted to four matched groups of 20 experienced ITC users. In addition to the subjective experiences of the users, the results were checked using insertion gain (IG) measurements. The results indicate that too sharp sound quality from paper rustle, from running water and from use of kitchen utensils is a common problem that it is important to be aware of. The possibility of maximal venting is of special importance in order to avoid autophony. Feedback may be a problem, especially when maximal venting is necessary. However, for several models of ITC, feedback is, in reality, a minor problem. High cost of batteries may be a problem for persons with ITC using 10/230 batteries. IG measurements indicated that a gain of approximately 0.3 in relation to the hearing losses was preferred. It may be advantageous to choose a model of ITC that has extensive flexibility.