Extraction of Cochlear Non-linearities with the Bispectral Analysis

Abstract

SummaryObjectives: Transient Otoacoustic Emission (TEOAEs) are low intensity sounds generated by active mechanisms in the cochlea and elicited by broadband and short acoustic stimuli. TEOAEs are a quick, non-invasive, and very reliable measure to objectively assess the peripheral auditory system. In the current study, we present a recent technique to extract and evaluate non-linearities in TEOAEs, and apply it for the preliminary analysis of TEOAE recordings of a group of worker of a fiberglass manufacturing facility exposed to styrene solvent. Methods:Bispectral analysis was applied to TEOAEs to extract the quadratic frequency couplings (QFCs) in TEOAEs. Amplitude of QFCs was calculated in a group of 7 styreneexposed workers (14 ears) and compared with normative results obtained on normal hearing young adults. Results: Difference in amplitude of QFCs were found between workers and controls. In workers, TEOAE non-linear components were found in the 1.5 -4 kHz frequency range, whereas in control subjects they were found in a lower frequency region, ranging from 1 to 3 kHz. Conclusion:The amplitude of QFCs highlighted differences in TEOAEs recorded among workers and controls.

Audiological Tests Used in the Evaluation of the Effects of Solvents on the Human Auditory System: A Mixed Methods Review

“…TEOAEs were used in six studies and DPOAEs in other six studies. TEOAE amplitudes were lower (i.e., poorer) among solvent-exposed workers than unexposed participants in four studies, 16 31 60 63 one did not find significant differences between groups, 39 and one of them did not report if differences were found. 62 Regarding DPOAE, three studies reported lower DPOAE amplitudes for the samples of workers exposed to solvents than the control groups.…”

“…Considering both statistical differences between exposed and unexposed participants, as well as the presence of clinically abnormal results in the applied tests, only two of the included studies did not test and consequently could not have shown impairment in the central auditory nervous system (CANS). 30 31 Several studies concluded that solvents may trigger central auditory dysfunction even when participants have normal-hearing audiometric thresholds. 16 20 28 29 Thirteen studies which tested auditory performance in the peripheral auditory system did not find an adverse effect of solvent exposure on peripheral auditory structures as measured by the following methodologies: pure-tone audiometry, 8 32 33 34 35 36 37 38 acoustic reflex threshold (ART), 34 TEOAE, 39 and ABR.…”

Evaluation of potential health effects associated with occupational and environmental exposure to styrene – an update

“…Sisto et al (2013) reportedly studied nine styrene-exposed workers and 13 controls, hence there is an unexplained discrepancy in the number of study subjects reported in these studies. Chiaramello, Moriconi, and Tognola (2014) found a difference in amplitude of QFCs between the workers and controls with the workers showing TEOAE non-linear components in the 1.5-4 kHz frequency range and the controls showing these components in a lower frequency region, ranging from 1 to 3 kHz. The authors concluded the QFCs amplitude demonstrated differences in TEOAEs between the workers and controls, although the study's small sample size and need for further confirmation in a larger study was acknowledged.…”