Authors: Lana Biot1*; Laura Jacxsens1; Emilie Cardon1; Huib Versnel2; Annick Gilles1; Vincent Van Rompaey1; Marc J.W. Lammers1
1University of Antwerp
2UMC Utrecht
Background Objective assessment of cortical auditory processing is challenging and mainly relies on evaluations that require the patient’s active participation in traditional speech-in-noise tests. A previous study by our group investigated the value of cortical auditory evoked potentials (CAEPs) evoked in response to auditory change stimuli, known as acoustic change complexes (ACCs), as an objective measurement of auditory performance in hearing impairment.
Method In 24 normal-hearing subjects and 13 age-matched hearing impaired subjects, ACCs were recorded in response to 12% frequency increases at four base frequencies (0.5, 1, 2 and 4 kHz). ACC amplitudes and latencies were compared to frequency discrimination thresholds at each base frequency, and to speech perception in noise.
Results Frequency discrimination and speech perception in noise were significantly better for larger ACC N1-P2 amplitudes and shorter N1 latencies, whereas neither frequency discrimination and speech perception did not correlate with onset CAEP amplitude or latency. Multiple regression analysis for prediction of speech perception in noise revealed that the strongest model was obtained by averaging over three frequencies (1, 2 and 4 kHz) with two significant predictors: hearing loss (R² = 0.52) and ACC latency (R² = 0.35). Thus, explaining 87% of the variance, this model indicates that subjects with longer ACC latencies have worse speech perception in noise than subjects with comparable hearing thresholds and shorter ACC latencies.
Conclusion In a previous study by our group, the ACC N1 latency was found to be a good predictor of speech perception. In our upcoming ACCEPT study, we will validate this predictive model in a larger study population (n = 80, aged 18-65 years) equally divided into a normal hearing group and a hearing impaired group. If successful, such a model will aid clinicians in their evaluation of auditory performance, in particular when behavioral testing is unreliable.
If instead of a frequency step increase or decrease, what if the there was a slower transition from one frequency to another? The same question could apply to the case where the transition between two sustained vowel sounds were gradual. In both of these cases there is a clear and obvious acoustic change. If I were inclined to guess, I bet that the ACC would vanish under these conditions
Indeed. A previous paper of our research group has done research about the rate of the frequency change (Vonck et al., 2019 JARO). The slower the rate, the lower the ACC amplitude and the ACC would indeed vanish in the noise.
This is also true for the contrary. If the rate would be too fast, it would result in a ‘click’ instead of a fluent frequency increase.
We chose a 12% frequency increase for 3 ms because it results in a good S/N ratio in order to extract the ACC-amplitude.
hey … i’m curious regarding the study is there any way that i get more information regarding this im looking forward to work on this topic for my desertation work
thank you .