[Effect of venting the ear mold on speech discrimination in masking noise]

In this study the importance of in situ measurement during the fitting of a hearing aid is clearly emphasized. Reliable evaluation of the real ear gain can be achieved only with this method, and hence the assessment of the advantages of earmold modifications on the hearing aid. In particular, the gain can be evaluated by the person fitting the aid. The insertion of a vent into an earmold raises the listening comfort of the hearing-impaired person. The speech intelligibility in background noise may also improve. We analysed the effect of earmold venting on speech intelligibility under different background noise conditions. We found that venting improves the speech intelligibility, especially in background noise simulating modulated speech. Our example clearly demonstrates the importance of an exact control of the hearing aid fitting by the physician. In one case a vent ended at the ear canal wall so that no improvement of hearing comfort could be expected. A new earmold was made and the effect on insertion gain was demonstrated when enlarging the vent step by step.