The Effects of Age on the Perception of Frequency in Noise

Difficulty understanding speech in the presence of background noise is one of the most common complaints of older adults, both with and without hearing loss. One possible contributing factor is an age-related decline in neural synchrony (e.g., phase locking). Tones-in-noise were used to disrupt rate-place coding of frequency and to encourage participants to use phase-locked representations of frequency during a behavioral frequency discrimination task. Thirteen Fourteen adults participated (five younger, aged 21-29; three four middle aged, 41-50; and five older, aged 61-80). Participants had clinically normal hearing sensitivity (≤ 25 dB HL at octave frequencies 250 – 4000 Hz). Tone-in-noise detection thresholds and frequency discrimination limens (FDLs) were obtained at 500 and 1000 Hz, separately. Tone level was 60 dB SPL; octave-wide noise was centered at the test frequency. FDLs were tested in three conditions: quiet, +5, and +10 dB. Conditions at +5 and +10 dB used SNRs relative to each participant’s tone-in-noise detection thresholds. The Words-in-Noise test was used to assess speech-in-noise understanding. Preliminary findings indicate that tone-in-noise detection thresholds were not significantly different across age groups; however, detection thresholds for 1000 Hz were significantly higher (poorer) than for 500 Hz. Frequency discrimination limens were significantly poorer (larger) in the presence of noise; however, no significant age effects were found. Speech-in-noise understanding was not significantly different across age groups. Frequency discrimination results indicate that the presence of noise worsened FDLs, as expected. The presence of noise may reduce the effectiveness of some neural coding strategies available to listeners.