Biomedical subjects

John F Houde

Publications and source records attributed to John F Houde.

3 recordsLinked to original sources

PubMed2006

Magnetoencephalographic evidence for a precise forward model in speech production.

Electroencephalography and magnetoencephalography studies have shown that auditory cortical responses to self-produced speech are attenuated when compared with responses to tape-recorded speech, but that this attenuation disappears if auditory feedback is altered. These results suggest that auditory feedback during speaking is processed by comparing the feedback with its internal prediction. The present study used magnetoencephalography to investigate the precision of this matching process. Auditory responses to speech feedback were recorded under altered feedback conditions. During speech production, the M100 amplitude was maximally reduced to the participants' own unaltered voice feedback, relative to pitch-shifted and alien speech feedback. This suggests that the feedback comparison process may be very precise, allowing the auditory system to distinguish between internal and external sources of auditory information.

Acoustic Stimulation↗

PubMed2002

Modulation of the auditory cortex during speech: an MEG study.

Several behavioral and brain imaging studies have demonstrated a significant interaction between speech perception and speech production. In this study, auditory cortical responses to speech were examined during self-production and feedback alteration. Magnetic field recordings were obtained from both hemispheres in subjects who spoke while hearing controlled acoustic versions of their speech feedback via earphones. These responses were compared to recordings made while subjects listened to a tape playback of their production. The amplitude of tape playback was adjusted to match the amplitude of self-produced speech. Recordings of evoked responses to both self-produced and tape-recorded speech were obtained free of movement-related artifacts. Responses to self-produced speech were weaker than were responses to tape-recorded speech. Responses to tones were also weaker during speech production, when compared with responses to tones recorded in the presence of speech from tape playback. However, responses evoked by gated noise stimuli did not differ for recordings made during self-produced speech versus recordings made during tape-recorded speech playback. These data suggest that during speech production, the auditory cortex (1) attenuates its sensitivity and (2) modulates its activity as a function of the expected acoustic feedback.

Adult↗

PubMed2002

Sensorimotor adaptation of speech I: Compensation and adaptation.

When motor actions (e.g., reaching with your hand) adapt to altered sensory feedback (e.g., viewing a shifted image of your hand through a prism), the phenomenon is called sensorimotor adaptation (SA). In the study reported here, SA was observed in speech. In two 2-hour experiments (adaptation and control), participants whispered a variety of CVC words. For those words containing the vowel /E/, participants heard auditory feedback of their whispering. A DSP-based vocoder processed the participants' auditory feedback in real time, allowing the formant frequencies of participants' auditory speech feedback to be shifted. In the adaptation experiment, formants were shifted along one edge of the vowel triangle. For half the participants, formants were shifted so participants heard /a/ when they produced /E/; for the other half, the shift made participants hear /i/ when they produced /E/. During the adaptation experiment, participants altered their production of /E/ to compensate for the altered feedback, and these production changes were retained when participants whispered with auditory feedback blocked by masking noise. In a control experiment, in which the formants were not shifted, participants' production changes were small and inconsistent. Participants exhibited a range of adaptations in response to the altered feedback, with some participants adapting almost completely, and other participants showing very little or no adaptation.

Adaptation, Physiological↗