Rapid Brain Adaptation to Hearing Amplification: A Randomized Crossover Trial of Personal Sound Amplification Products

Abstract

Understanding speech in noise is a common challenge for older adults, often requiring increased listening effort that can deplete cognitive resources and impair higher-order functions. Hearing aids are the gold standard intervention for hearing loss, but cost and accessibility barriers have driven interest in alternatives such as Personal Sound Amplification Products (PSAPs). While PSAPs are not medical devices, they may help reduce listening effort in certain contexts, though supporting evidence remains limited. This study examined the short-term effects of bilateral PSAP use on listening effort using self-report measures and electroencephalography (EEG) recordings of alpha-band activity (8-12 Hz) in older adults with and without hearing loss. Twenty-five participants aged 60 to 87 years completed a hearing assessment and a phonological discrimination task under three signal-to-noise ratio (SNR) conditions during two counterbalanced sessions (unaided and aided). Results showed that PSAPs significantly reduced self-reported effort. Alpha activity in the left parietotemporal regions showed event-related desynchronization (ERD) during the task, reflecting brain engagement in response to speech in noise. In the unaided condition, alpha ERD weakened as SNR decreased, with activity approaching baseline. PSAP use moderated this effect, maintaining stronger ERD under the most challenging SNR condition. Reduced alpha ERD was associated with greater self-reported effort, suggesting neural and subjective measures reflect related dimensions of listening demand. These results suggest that even brief PSAP use can reduce perceived and neural markers of listening effort. While not a replacement for hearing aids, PSAPs may offer a means for easing cognitive load during effortful listening. ClinicalTrials.gov, NCT05076045, https://clinicaltrials.gov/study/NCT05076045.

Keywords: alpha power; hearing loss; listening effort; personal sound amplification products.

Figure 1.

CONSORT flow diagram. Flow chart showing inclusion and participation throughout the study.

Figure 2.

Epochs. Continuous EEG data were segmented into 2,500 ms epochs time-locked to the onset of the first word. Each epoch included a 500  ms prestimulus baseline and a 2,000  ms post-stimulus period. Analyses were restricted to alpha activity elicited by the first word, focusing on the 0 to 500  ms window following stimulus onset.

Figure 3.

Self-reported listening effort scores for the unaided and aided sessions. Participants rated their perceived effort on a seven-point Likert scale, where higher scores indicated greater effort. A significant reduction in effort was observed in the aided session relative to the unaided session.

Figure 4.

Evoked neural oscillations over time, expressed as percent change from baseline. (A) Group mean temporal spectral evolution (TSE), time-locked to the onset of the first word, for all three signal-to-noise ratio (SNR) conditions in the unaided session. The spectrogram depicts a change in oscillatory activity recorded from electrode CP5. (B) Same as (A), but for the aided session. (C) Time course of alpha activity (8–12 Hz) across the epoch window. shaded areas around the lines represent the standard error of the mean. Positive values indicate event-related synchronization (ERS), reflecting increased alpha power relative to baseline, while negative values indicate event-related desynchronization (ERD), reflecting decreased alpha power relative to baseline.

Figure 5.

Alpha-band activity (8–12 Hz) differences across signal-to-noise ratio (SNR) conditions and sessions. (A) Scalp topographies showing percent change in alpha-band activity relative to baseline for each of the three SNR conditions, as well as the contrast between the two extreme conditions (+3 dB vs. −3 dB), during the unaided session. Black dots indicate the significant cluster (FT7, C5, T7, TP7, CP5, P3, P5, P7, P9, and CB1) showing an effect of SNR in the unaided condition. (B) Same as (A), but for the aided session. (C) Scalp topographies showing the difference in alpha-band activity between the aided and unaided sessions for each SNR condition. (D) Statistical interaction between session and SNR on alpha-band activity averaged over the left parietotemporal cluster. Positive values reflect increased alpha activity (event-related synchronization, ERS), whereas negative values reflect decreased alpha activity (event-related desynchronization, ERD), relative to baseline.

Figure 6.

Predicted behavioral outcomes as a function of alpha-band activity (8–12 Hz), averaged across electrodes in the left parietotemporal cluster (FT7, C5, T7, TP7, CP5, P3, P5, P7, P9, and CB1). Predictions are derived from linear mixed-effects (LME) models treating alpha power as a continuous predictor. Each point reflects the model-predicted behavioral value for a given participant in each session (aided and unaided). Panels show predicted values for (A) self-reported listening effort, (B) phoneme discrimination accuracy, and (C) reaction time. Colored lines show the fixed-effect regression fits for each session. The black line represents the overall fixed-effect of alpha power across sessions. Shaded areas around the lines indicate the standard error of the estimate.