Bone Conduction Transmission and Head‐Shadow Effects for Unilateral Hearing Losses Fit with Transcranial Cic Hearing Aids

<p> Bone conduction transmission and head&hyphen;shadow effects were determined with transcranial completely&hyphen;in&hyphen;the&hyphen;canal (TCCIC) CROS hearing aids. Five subjects with documented profound unilateral hearing loss and experience with traditional CROS/BICROS fittings (TCROS) were tested with a CIC hearing aid placed in their poorer ear. Peak SPL was measured at the tympanic membrane and ranged from 105&ndash;115 dB SPL at 2000 Hz. Pure&hyphen;tone crossover thresholds and functional gain tested at frequencies from 250&ndash;8000 Hz varied considerably more than the SPL measures. The pure&hyphen;tone results indicated that sensitivity in the better ear was moderately associated with functional gain across frequency. Speech recognition was then tested in the sound field in two conditions: direct (noise in the poorer ear, speech in the better ear) and indirect (noise in the better ear, speech in the poorer ear) at S/Ns of &minus;6, 0, +6, +12, and quiet. The TCCIC fittings were more effective than TCROS aids across S/Ns, particularly in the direct condition. In the indirect condition, the two fittings performed similarly. When data were pooled across conditions, the TCCIC aids provided better word recognition than the TCROS aids, particularly for those subjects with greater sensitivity in the better ear.</p>