Investigating measures of high-frequency hearing function and the effects of noise exposure

Abstract

Many young adults engage in loud activities, which can cause noise-induced hearing loss (NIHL). Some studies suggest that NIHL and age-related hearing loss (ARHL) lead to relatively rapid shifts in the hearing threshold level (HTL) of the extended high frequency (EHF) range (> 8 kHz). It has been hypothesised that NIHL may first present with HTL elevations in the EHF range before the conventional audiometric frequency (CAF) range of 0.25 to 8 kHz. In this research, three studies were reported related to hearing in the EHF region. Study 1A aimed to assess the effect of noise exposure on different measures of EHF hearing. It also aims to establish which parameters of EHF-OAEs can derive the highest signal amplitudes and signal to noise ratio (SNR). Finally, it aims to determine which EHF-OAEs better predict EHF-HTL. Data were collected from 58 young adults (18-34 years) with normal hearing in CAF-range, using EHF pure tone audiometry (EHF-PTA), transient evoked otoacoustic emissions OAE (EHF-TEOAE) recorded with double-evoked (DE) using high-pass filter (HPF) and toneburst (TB 10 kHz) stimulus waveform, as well as distortion product OAE (EHF-DPOAE) recorded with (70/70) and (65/55) stimulus level paradigm. Noise exposure history was quantified using noise exposure structured interview (NESI). It was found that EHF-HTL showed more association with noise exposure than CAF-HTL. The current study also showed measuring EHF-DPOAEs using (70/70) dB SPL can evoked greater amplitude for the EHF-range. But when assessing which EHF-OAEs measurement can predict EHF-HTL it was found that EHF-DPOAEs recorded with (65/55) dB SPL predict EHF-HTL more strongly than EHF-DPOAEs using (70/70). It was also found that EHF-TEOAEs (TB and HPF) might predict EHF-HTL equally. Study 1B aimed to observe changes in EHF measurement in association with noise exposure over 16 months. It also aims to assess the correlation between EHF-OAEs and EHF-HTL. Three visits were conducted, each separated by 6–8 months (baseline [n = 58], phase 1 [n = 43], and phase 2 [n = 26]). The results showed no discernible hearing changes over 8–16 months, except for CAFHTL and EHF-HTL over 16 months, due to noise exposure but the pattern of results was complex, and it is speculated that they may have been influenced by possible calibration drift over the duration of the study. Study 2 aimed to assess whether the correlation between audiogram fine structure (AFS) and normal HTL and TEOAEs in the EHF range would be similar to that seen in the CAF range. Data for Studies 2 and 3 were collected simultaneously from 28 subjects. The results did not show the correlations in the EHF-range that have been reported in the CAF range, which may be due to weaker interference between forward and reverse cochlear travelling waves in the most basal region (EHF) compared to most apical areas (CAF) or a difference in cochlear mechanical properties. Study 3 aimed to establish whether evoking the novel use of EHF-TEOAEs with maximum length sequences (MLS) or DE paradigm can show greater SNR. The SNR from EHF-TEOAE recorded using DE-paradigm were statistical significantly better than the SNR from EHF-TEOAE using MLS. In addition, only the EHF-TEOAE recorded using DE technique in the 9.4-kHz ½-octave band achieved an SNR that would be clinically useful (> 6 dB SNR)

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ORCID for Ben Lineton: orcid.org/0000-0003-4784-7762

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