High-frequency amplification with ITC-HA and BTE-HA. A comparative investigation.

The purpose of the present investigation was to evaluate the magnitude of selective high-frequency amplification obtained by an in-the-canal hearing aid (ITC-HA), and to compare it with that obtained with a conventional behind-the-ear hearing aid (BTE-HA) with an open mould. 22 subjects (20 males, 2 females) at a median age of 66 years (range 46-84) were included in the investigation. All suffered from a bilateral high-frequency hearing loss with normal or near-normal hearing thresholds at 0.5 and 1 kHz. Insertion gain measurements demonstrated that the ITC-HA gives a significantly higher amplification in the high-frequency area, when compared with the BTE-HA, though neither of the hearing aids amplified as much as indicated by the POGO strategy. Although a better amplification in the high-frequency area was obtained with the ITC-HA, it did not result in significantly better speech recognition when compared with the BTE-HA. At the hearing aid fitting, all subjects preferred the ITC-HA, and after an observation period of one year, 68% of those fitted used the aid continuously. Based on the investigation it is concluded that hearing-impaired persons can be fitted with an ITC-HA, even if they have pronounced high-frequency hearing loss, and that this type of aid is preferred by the hearing-impaired to the conventional BTE-HA.