Effects of Amplification on Neural Phase Locking, Amplitude, and Latency to a Speech Syllable.

The participants were first-time hearing aid users, so the results may not apply to experienced hearing aid users. Two participants were removed from phase-locking analyses, and some noise or cortical data were missing for others. The hearing aids were open-fit, so unaided sound entered the ear canal alongside the amplified signal; this mixing and processing delay may have reduced measurable amplification effects. Adequate aided audibility above 2000 Hz was not achieved because higher-frequency gain caused feedback or discomfort. Sound-field testing allowed slight movement, which could reduce timing precision, although the authors state robust responses were obtained. The noise level was relatively favorable, 70 dB SPL babble with 80 dB SPL speech, so lack of noise effects may not generalize to harder listening. The study measured brain responses, not behavioral speech perception or real-world hearing aid benefit. Large individual differences were noted, so the group results may not predict every patient.

The authors reported no conflicts. Funding included the University of Maryland Department of Hearing and Speech Sciences, the Hearing Health Foundation, NIH-NIDCD, and Widex USA. Widex USA provided the hearing aids and contributed to subject compensation.

Do not read the improved brain responses at 65 dB SPL as proof that hearing aids improve speech understanding or work in noise. The study measured brain responses, not listening ability, and amplification did not improve responses in noise.