Localization and speech perception by unilateral BAHA users

Abstract

Objectives: Patients with unilateral hearing loss report difficulty hearing conversation on their impaired side, inability to localize sound, and diminished understanding of speech in background noise. The Bone-Anchored Cochlear Stimulator, or BAHA, has been shown to be useful for persons with unilateral complete sensorineural hearing loss in improving speech perception in noise using the Hearing-in-Noise Test (HINT). The purpose of the present study is to evaluate the effectiveness of BAHA in sound localization and speech tasks in noise for unilateral sensorineurally impaired listeners. Methods: Prospective study of 20 unilaterally hearing impaired subjects with sensorineural loss. All subjects were implanted with a BAHA on the poorer hearing side. All subjects underwent audiometric evaluation under headphones preoperatively to classify loss and degree. Soundfield measurements were conducted in a calibrated audiometric suite: HINT sentences and localization testing, with and without a CROS hearing aid or BAHA. Localization measurement was performed using a specialized array of 7 calibrated speakers at head level separated by 15 degrees. An error analysis matrix was generated to evaluate the confusions and degrees of separation of errors. Results: Results to date indicated that accuracy of identification of speaker localization was poorer than 50% for 100% of the sample in both unaided and aided conditions. Errors were severe, ie, more than 30 degrees of arc. In contrast, the improvement in speech perception, as obtained in the previous study, was observed. Conclusions: Use of the CROS or BAHA did not result in improved performance on the localization task for this sample.