Effects of reversible noise exposure on the suppression tuning of rabbit distortion-product otoacoustic emissions

• DOI: 10.1121/1.1419094
• Publication Date: 2002-07-26T14:10:47Z
• Authors: MacKenzie A. Howard; Barden B. Stagner; Brenda L. Lonsbur...; Glen K. Martin
• Keywords: Octave band; Auditory fatigue

Distortion-product otoacoustic emissions (DPOAEs) at 2f1-f2 can be suppressed by the introduction of a third “suppressor” tone. Plotting suppression DPOAE level against changing frequency and suppressor produces frequency-tuning functions referred to as tuning curves (STCs). The dominant features STCs, including their shape, are similar neural (NTCs) recorded from single auditory nerve fibers. However, recent findings using reversible diuretics suggest that STCs do not provide same measure cochlear selectivity provided NTCs. To determine if also insensitive adverse effects excessive sounds, present study exposed rabbits moderate-level noise produced temporary threshold shift-like (TTS) on DPOAEs, examined influence such exposures STCs. DPOAEs were primary tones with geometric-mean frequencies centered 2.8 or 4 kHz, L1 L2 values 45/45, 50/35, 50/50, 55/45 dB SPL. obtained before during recovery for period approximately 2 h immediately following, 1, 2, 3, 7 d post-exposure kHz octave band noise, levels durations sufficient cause significant but reductions in levels. STC data included tip center frequency, threshold, Q10dB measures criteria 6, 9, 12 dB. Recovery was variable between animals, all recovered fully post-exposure. measured TTS typically tuned slightly higher while thresholds tended decrease increase. Together, results indicate that, despite similarities general properties NTCs, these two types affected differently following insult.