Objective measurement of physiological signal-to-noise gain in the brainstem response to a synthetic vowel

Relative contribution of envelope and fine structure to the subcortical encoding of noise-degraded speech

“…The resilience of the brainstem FFR at F0 (but not higher F1 harmonics) in the presence of noise has been noted by a number of investigators 22 and suggests that neural synchronization at the F0 is relatively robust to acoustic interference. However, it remains possible that stimuli with more dynamically changing F0 than those used here would have produced stronger noise-related changes in pitch coding.…”

“…15 Multiple responses to F0 across the cochlear array would tend to reinforce one another at the population level and consequently offer some resilience/redundancy in pitch cues observed here in scalp-recorded FFRs (for discussion of other mechanisms of F0 enhancement see Refs. 15,22).…”

“…FFR studies showing a maintenance or even facilitation of the F0 response with additive noise. 22 Physiologically, the robustness of F0 coding to noise could reflect the engagement of low-frequency "tails" of basal, high-frequency neurons that phase-lock to the common F0 across cochlear channels. 15 Multiple responses to F0 across the cochlear array would tend to reinforce one another at the population level and consequently offer some resilience/redundancy in pitch cues observed here in scalp-recorded FFRs (for discussion of other mechanisms of F0 enhancement see Refs.…”

Automatic Recognition of Speech-evoked Brainstem Responses to English Vowels

“…Recent evidence suggests that the speech-evoked ABR can provide an important window into auditory processing of speech in normal and hearing impaired individuals (Prévost et al, 2013;. One particular difficulty with hearing assessment is that it is limited by current tests, which usually use artificial signals like tones or clicks that do not allow a clear assessment of auditory function for speech communication .…”

“…On the other hand, the FFR represents the neural response that directly follows the harmonics of speech and is usually most prominent in the region of the first formant (F1) (Sadeghian et al, 2015). Typically, the stimulus is presented to the subject in two polarities (original and inverted), and the EFR is obtained by averaging the responses to both stimulus polarities, while the FFR is obtained by averaging the response to one polarity and the negative of the response to the other polarity (Prévost et al, 2013;Aiken and Picton, 2008). A simplified model of how the EFR and FFR are thought to be generated is shown in Figure 2.10 below.…”