Wireless CROS Versus Transcranial CROS for Unilateral Hearing Loss

Patients with unaidable sensorineural hearing loss in one ear and normal hearing in the opposite ear can present a challenge to audiologists. At least two recommendations may be available. One approach is to attempt to minimize the communication problems associated with unilateral hearing loss by recommending preferential seating or counseling the patient to place the normal ear so it faces the desired signal. Another approach to improving communication for patients with unilateral hearing loss was the introduction of CROS amplification to the good ear (Harford & Barry, 1965). This original method of amplification provided minimal gain between 800 and 1,500 Hz. Significant gain was provided above 1,500 Hz. Thus, patients most likely to receive the greatest benefit from CROS amplification were those having mild hearing loss above 1,500 Hz in the better ear. Numerous reports (Courtois, Johansen, Larsen, & Beilin, 1988; Harford, 1969; Harford & Barry, 1965; Harford & Dodds, 1966; Punch, 1988) strongly suggest that success with CROS amplification is directly related to the hearing loss in the better ear. If hearing in the better ear is within normal limits, the prognosis with CROS amplification is guarded. On the other hand, if a mild hearing loss is present above 1,500 Hz, greater patient acceptance may occur. To overcome the problems associated with using CROS amplification for patients with normal hearing in one ear, several reports (Chartrand, 1991; McSpaden, 1990; McSpaden & McSpaden, 1989; Miller, 1989; Sullivan, 1988) suggest another fitting strategy. This fitting requires coupling a high gain/high output, in-the-ear (ITE) or behind-the-ear (BTE) hearing aid to the unaidable ear, allowing the amplified signal to transfer to the cochlea of the good ear by bone conduction through the cranium. This fitting has been called “transcranial” or “internal CROS.” Reports by Chartrand (1991), McSpaden (1990), McSpaden and McSpaden (1989), Miller (1989), and Sullivan (1988) indicate that many listeners with unilateral hearing loss found transcranial CROS fittings provided a “more natural” sound than conventional CROS fittings, provided improved localization of a metallic sound from the aided side, and improved listening in noise when the signal was on the side of the impaired ear. In addition, patients did not report the harshness often associated with conventional CROS fittings. The present study was initiated to determine if patients with unilateral hearing loss would find a transcranial CROS fitting preferable to a wireless CROS. If this is true, then the results could provide another fitting option for patients with unilateral hearing loss. Also reported is a new