Speech Auditory Brainstem Responses in Adult Hearing Aid Users: Effects of Aiding and Background Noise, and Prediction of Behavioral Measures

Abstract

Evaluation of patients who are unable to provide behavioral responses on standard clinical measures is challenging due to the lack of standard objective (non-behavioral) clinical audiological measures that assess the outcome of an intervention (e.g., hearing aids). Brainstem responses to short consonant-vowel stimuli (speech-auditory brainstem responses [speech-ABRs]) have been proposed as a measure of subcortical encoding of speech, speech detection, and speech-in-noise performance in individuals with normal hearing. Here, we investigated the potential application of speech-ABRs as an objective clinical outcome measure of speech detection, speech-in-noise detection and recognition, and self-reported speech understanding in 98 adults with sensorineural hearing loss. We compared aided and unaided speech-ABRs, and speech-ABRs in quiet and in noise. In addition, we evaluated whether speech-ABR F0 encoding (obtained from the complex cross-correlation with the 40 ms [da] fundamental waveform) predicted aided behavioral speech recognition in noise or aided self-reported speech understanding. Results showed that (a) aided speech-ABRs had earlier peak latencies, larger peak amplitudes, and larger F0 encoding amplitudes compared to unaided speech-ABRs; (b) the addition of background noise resulted in later F0 encoding latencies but did not have an effect on peak latencies and amplitudes or on F0 encoding amplitudes; and (c) speech-ABRs were not a significant predictor of any of the behavioral or self-report measures. These results show that speech-ABR F0 encoding is not a good predictor of speech-in-noise recognition or self-reported speech understanding with hearing aids. However, our results suggest that speech-ABRs may have potential for clinical application as an objective measure of speech detection with hearing aids.

Keywords: Speech-ABR; aided speech-ABR; background noise; hearing aid; speech-in-noise performance.

Figure 1.

Test-ear mean (±1 SD) pure tone thresholds (black) and test-ear pure tone thresholds for each of the 98 participants (gray).

Figure 2.

Grand average speech-ABRs with prestimulus baseline in four panels: (a) aided and unaided in quiet, (b) aided and unaided in noise, (c) aided quiet and aided noise, and (d) unaided quiet and unaided noise. Effects of aiding: displayed in panels (a) and (b) showing earlier latencies and larger amplitudes in the aided compared to unaided speech-ABRs in quiet (a) and in noise (b). Effects of background noise: displayed in panels (c) and (d) showing limited effects of noise on both aided (c) an unaided (d) speech-ABR latencies and amplitudes. Shading of traces in all panels represents 1 SEM.

Figure 3.

Comparison of mean (error bars represent ±1 SD) aided versus unaided speech-ABR peaks and speech-ABR F0 encoding, individual data are shown in gray, and significant differences between aided and unaided are marked with an asterisk (*). Effects of aiding on latencies: Aided versus unaided in quiet (a) and aided versus unaided in noise (b) both showing earlier aided latencies for all speech-ABR peaks (V, A, D, E, F, and O) with no difference between aided and unaided in F0 encoding latencies. Effects of aiding on Amplitudes: Aided versus unaided in quiet (c) and aided versus unaided in noise (d) both showing larger aided amplitudes for speech-ABR peaks (VA, D, and F) and F0 encoding amplitudes, with no difference between aided and unaided in the amplitudes of peaks E and O.

Figure 4.

Complex cross correlations of speech-ABRs with the 40 ms [da] F0 waveform obtained from one participant with significant (detected) responses for all four conditions: (a) aided quiet, (b) aided noise, (c) unaided quiet, and (d) unaided noise. Effects of aiding: similar latencies but larger aided amplitudes both in quiet ((a) vs. (c)) and in noise ((b) vs. (d)). Effects of background noise: earlier latencies in quiet than in noise with similar amplitudes both in aided ((a) vs. (b)) and unaided ((c) vs. (d)) speech-ABR F0 encodings.

Figure 5.

Comparison of mean (error bars represent ±1 SD) quiet versus noise speech-ABR peaks and speech-ABR F0 encoding, individual data are shown in gray, and significant differences between quiet and noise are marked with an asterisk (*). Effects of background on latencies: Aided quiet versus aided noise (a) and unaided quiet versus unaided noise (b) both showing earlier F0 encoding latencies in quiet, with no difference between quiet and noise in the latencies of speech-ABR peaks (V, A, D, E, F, and O). Effects of background on Amplitudes: Aided quiet versus aided noise (c) and unaided quiet versus unaided noise (d) showing no difference between quiet and noise in the amplitudes of speech-ABR peaks (V, A, D, E, F, and O) and in F0 encoding amplitudes.