Speech-in-noise and subjective benefit with active middle ear implant omnidirectional and directional microphones: a within-subjects comparison.

Objectives: 1) To evaluate speech understanding in noise by comparing signal-to-noise ratios for 50% correct word understanding (SNR50) using an omnidirectional and a directional microphone audio processor (AP) in 4 different noise conditions. 2) To compare subjective speech understanding abilities, spatial hearing abilities, and qualitative hearing performance with the 2 processors.

Study Design: A prospective, single-subjects repeated-measures study design was used to compare speech understanding performance with the 2 APs acutely and after 6 weeks' acclimatization time.

Setting: Tertiary referral center.

Patients: Thirteen experienced unilateral German-speaking active middle ear implant users with either mixed or conductive hearing loss were enrolled.

Intervention: Directional audio processor.

Main Outcome Measures: SNR50 obtained from 4 different noise conditions.

Results: SNR50s with the directional AP were lower (better) than with the omnidirectional AP in all noise conditions, although there were no changes in aided PTA thresholds. In acute testing, the mean SNR50 showed a significant directional advantage (DA) for the directional AP in the S0N0 condition of 1.3 dB, in S0NVSB 2.3 dB, in S0Ncont 3.1 dB, and in S0N180 4.5 dB. As expected, the largest DA was found in the S0N180 condition. No DA was expected in the S0N0 condition but was present. After 6 weeks of acclimatization time, no significant change from the acute testing was found, suggesting that patients experienced improved performance with the directional AP, even without acclimatization time. There was no significant change in subjective questionnaire outcomes.

Conclusion: The directional AP yields immediately improved speech understanding in noise.