Enhancing the sensitivity of the envelope-following response for cochlear synaptopathy screening in humans: The role of stimulus envelope

Abstract

Auditory de-afferentation, a permanent reduction in the number of innerhair-cells and auditory-nerve synapses due to cochlear damage or synaptopathy, can reliably be quantified using temporal bone histology and immunostaining. However, there is an urgent need for non-invasive markers of synaptopathy to study its perceptual consequences in live humans and to develop effective therapeutic interventions. While animal studies have identified candidate auditory-evoked-potential (AEP) markers for synaptopathy, their interpretation in humans has suffered from translational issues related to neural generator differences, unknown hearing-damage histopathologies or lack of measurement sensitivity. To render AEP-based markers of synaptopathy more sensitive and differential to the synaptopathy aspect of sensorineural hearing loss, we followed a combined computational and experimental approach. Starting from the known characteristics of auditory-nerve

Towards Personalized Auditory Models: Predicting Individual Sensorineural Hearing-Loss Profiles From Recorded Human Auditory Physiology

“…At the same time, RAM-EFR metric was involved in all feature sets that yielded the highest acc mean among feature sets that had equal number of combined metrics (Tables 2 and 3). This finding is consistent with the outcome of Parthasarathy and Kujawa (2018) and Vasilkov et al (2021), showing that EFRs to SAM or RAM are sensitive to CS. Moreover, the combined modeling and experimental study of Vasilkov et al (2021) showed that the adopted RAM-EFR marker (RAM with a 25% duty cycle) is minimally impacted by OHC damage.…”

“…The mean amplitude of each epoch was subtracted to correct for the baseline-drift. See Vasilkov et al (2021) for further details on the frequency-domain bootstrapping and noise-floor estimation method. The noise-floor corrected spectral magnitudes (M f k ) at the modulation frequency f 1 ¼ 120Hz and four harmonics, that is, f 2 to f 5 , were summed up to yield the EFR.…”

The variability in potential biomarkers for cochlear synaptopathy after recreational noise exposure

“…A study by the same lab could not find noise exposure as a predictor of EFR-strength (Prendergast et al, 2019). In contrast, animal studies (Möhrle et al, 2016;Shaheen et al, 2015) and those that used computational modelling of the auditory periphery or human data have shown the possible value of EFRs in diagnosing CS (Bharadwaj et al, 2015;Garrett & Verhulst, 2019;Keshishzadeh, Garrett, Vasilkov, et al, 2020;Paul et al, 2017;Vasilkov et al, 2021).…”

“…EFR strength was defined as the summation of the signal-to-noise spectral magnitude at fundamental frequency and the following three harmonics, i.e. 110, 220, 330 and Hz, if they were above the noise-floor (Vasilkov et al, 2021). Noise-floor corrected SAM and RAM EFRs are shown in Figure 2B and D. Arrows represent the EFR magnitudes at modulation frequency (110 Hz) and existent spectral peaks at corresponding harmonics.…”

“…EFR strength was defined as the summation of the signal-to-noise spectral magnitude at fundamental frequency and the following three harmonics, i.e. 110, 220, 330 and Hz, if they were above the noise-floor (Vasilkov et al, 2021) First, the baseline session was analyzed. Hearing-test results of audiometry, speech audiometry SRT, EFR strength, ABR-amplitudes and -latencies of waves I, III and V and I/V amplitude ratio were analyzed in relation to lifetime noise-exposure history.…”