I Akhoun1, S Gallégo, A Moulin, M Ménard, E Veuillet, C Berger-Vachon, L Collet, H Thai-Van. 1. Université Claude Bernard Lyon I, Université de Lyon, Laboratoire Neurosciences Sensorielles, Comportement, Cognition, CNRS UMR 5020, Hôpital Edouard Herriot, Pavillon U - 5, pl. d'Arsonval, F-69003 Lyon, France. idrick.akhoun@chu-lyon.fr
Abstract
OBJECTIVE: To investigate the temporal relationship between speech auditory brainstem responses and acoustic pattern of the phoneme /ba/. METHODS: Speech elicited auditory brainstem responses (Speech ABR) to /ba/ were recorded in 23 normal-hearing subjects. Effect of stimulus intensity was assessed on Speech ABR components latencies in 11 subjects. The effect of different transducers on electromagnetic leakage was also measured. RESULTS: Speech ABR showed a reproducible onset response (OR) 6ms after stimulus onset. The frequency following response (FFR) waveform mimicked the 500Hz low pass filtered temporal waveform of phoneme /ba/ with a latency shift of 14.6ms. In addition, the OR and FFR latencies decreased with increasing stimulus intensity, with a greater rate for FFR (-1.4ms/10dB) than for OR (-0.6ms/10dB). CONCLUSIONS: A close relationship was found between the pattern of the acoustic stimulus and the FFR temporal structure. Furthermore, differences in latency behaviour suggest different generation mechanisms for FFR and OR. SIGNIFICANCE: The results provided further insight into the temporal encoding of basic speech stimulus at the brainstem level in humans.
OBJECTIVE: To investigate the temporal relationship between speech auditory brainstem responses and acoustic pattern of the phoneme /ba/. METHODS: Speech elicited auditory brainstem responses (Speech ABR) to /ba/ were recorded in 23 normal-hearing subjects. Effect of stimulus intensity was assessed on Speech ABR components latencies in 11 subjects. The effect of different transducers on electromagnetic leakage was also measured. RESULTS: Speech ABR showed a reproducible onset response (OR) 6ms after stimulus onset. The frequency following response (FFR) waveform mimicked the 500Hz low pass filtered temporal waveform of phoneme /ba/ with a latency shift of 14.6ms. In addition, the OR and FFR latencies decreased with increasing stimulus intensity, with a greater rate for FFR (-1.4ms/10dB) than for OR (-0.6ms/10dB). CONCLUSIONS: A close relationship was found between the pattern of the acoustic stimulus and the FFR temporal structure. Furthermore, differences in latency behaviour suggest different generation mechanisms for FFR and OR. SIGNIFICANCE: The results provided further insight into the temporal encoding of basic speech stimulus at the brainstem level in humans.