Overexposure effects of a 1-kHz tone on the distortion product otoacoustic emission in humans

Abstract

The effects of overexposure on the properties of distortion product otoacoustic emissions (DPOAEs) are investigated. In total, 39 normal-hearing humans were monaurally exposed to a 1-kHz tone lasting for 3 min at an equivalent threshold sound-pressure level of 105.5 dB. The effects of overexposure were studied in two experiments (1) on the broadband DPOAE and (2) on the DPOAE fine structure, measured using a higher frequency resolution in a narrower frequency range. The obtained DPOAE shifts were compared to temporary threshold shift (TTS) obtained after a similar exposure. Similarities between DPOAE shifts and TTS were found in the affected frequency range and the time course of recovery. The amount of TTS was higher in the early recovery time (1-4-min postexposure), but similar to the DPOAE shift (even in absolute terms) at later recovery times (5-20-min postexposure). The DPOAE fine structure was not systematically changed after the exposure.

Recovery of distortion-product otoacoustic emissions after a 2-kHz monaural sound-exposure in humans: Effects on fine structures

“…Engdahl and Kemp (1996) found for their two subjects that the maximum to minimum ratio of the fine structure decreased, and the whole pattern shifted toward lower frequencies after the exposure. Reuter et al (2007) found for their 16 subjects that the effects were highly individual and no systematic change was observed, i.e., some subjects showed an increase in the depth of the fine structures while others showed a decrease, with no systematic shift in frequency. Results by Reuter et al (2007) may have been influenced by the methodological protocol for DPOAE assessment.…”

“…Reuter et al (2007) found for their 16 subjects that the effects were highly individual and no systematic change was observed, i.e., some subjects showed an increase in the depth of the fine structures while others showed a decrease, with no systematic shift in frequency. Results by Reuter et al (2007) may have been influenced by the methodological protocol for DPOAE assessment. That is, DPOAEs were measured with an ascending sweep in the range 903 f 2 (Hz) 2295 that took almost 7 min to complete.…”

“…According to the 1/2-octave shift, it was expected that a tonal exposure of 2 kHz would affect mostly the cochlear region around 3 kHz (Engdahl and Kemp, 1996;Reuter et al, 2007;Marshall et al, 2001). Therefore, DPOAEs were measured across a frequency range of approximately 1/3-octave centered at 3 kHz (geometric mean of the primaries).…”

“…One reason is the methods that require the generation (f 2 ) and the reflection component (2f 1 -f 2 ) are linearly related, and currently there is a lack of data showing whether this is true, both under normal conditions and under adverse (overexposured) conditions. Two studies have investigated whether there are systematic changes in the DPOAE fine structures of humans after acoustic overexposure (Engdahl and Kemp, 1996;Reuter et al, 2007). Both used a monaural narrow-band sound-exposure and monitored the fine structures at specific times during the recovery.…”

Characteristics of Noise Exposure During Solitary Trumpet Playing

“…Several investigations have compared TEOAEs or DPOAEs in subjects who have a history of noise exposure with controls without noise exposure. Results of studies examining DPOAEs and pure-tone thresholds in industrial workers, military personnel, construction-industry apprentices, and unexposed subjects have indicated that DPOAEs can be in agreement with pure-tone threshold shifts (Attias et al 1998;Balatsouras 2004;Seixas et al 2004;Reuter et al 2007) or can exhibit notable change (i.e., decreases) before changes in puretone thresholds suggesting that noise-induced cochlear damage may extend beyond that measurable with pure-tone threshold testing (Seixas et al 2005;Marshall et al 2009). …”