The amplitude of the auditory N1 component of the event‐related potential (ERP) is typically supp... more The amplitude of the auditory N1 component of the event‐related potential (ERP) is typically suppressed when a sound is accompanied by visual anticipatory information that reliably predicts the timing and identity of the sound. While this visually induced suppression of the auditory N1 is considered an early electrophysiological marker of fulfilled prediction, it is not yet fully understood whether this internal predictive coding mechanism is primarily driven by the temporal characteristics, or by the identity features of the anticipated sound. The current study examined the impact of temporal and identity predictability on suppression of the auditory N1 by visual anticipatory motion with an ecologically valid audiovisual event (a video of a handclap). Predictability of auditory timing and identity was manipulated in three different conditions in which sounds were either played in isolation, or in conjunction with a video that either reliably predicted the timing of the sound, the i...
Listeners hearing an ambiguous speech sound flexibly adjust their phonetic categories in accordan... more Listeners hearing an ambiguous speech sound flexibly adjust their phonetic categories in accordance with lipread information telling what the phoneme should be (recalibration). Here, we tested the stability of lipread-induced recalibration over time. Listeners were exposed to an ambiguous sound halfway between /t/ and /p/ that was dubbed onto a face articulating either /t/ or /p/. When tested immediately, listeners exposed to lipread /t/ were more likely to categorize the ambiguous sound as /t/ than listeners exposed to /p/. This aftereffect dissipated quickly with prolonged testing and did not reappear after a 24-hour delay. Recalibration of phonetic categories is thus a fragile phenomenon.
Humans can categorize vowels based on spectral quality (vowel identity) or pitch (speaker sex). S... more Humans can categorize vowels based on spectral quality (vowel identity) or pitch (speaker sex). Songbirds show similarities to humans with respect to speech sound discrimination and categorization, but it is unclear whether they can categorize harmonically structured vowel-like sounds on either spectrum or pitch, while ignoring the other parameter. We trained zebra finches in two experimental conditions to discriminate two sets of harmonic vowel-like sounds that could be distinguished either by spectrum or fundamental frequency (pitch). After the birds reached learning criterion, they were tested on new sounds that were either noise-vocoded versions of the trained sounds (sharing the spectral envelope with the trained sounds but lacking fine spectral detail from which pitch could be extracted) or sounds lacking the amplified harmonics (sharing only pitch with the trained sounds). Zebra finches showed no difference in the number of trials needed to learn each stimulus–response mapping. Birds trained on harmonic spectrum generalized their discrimination to vocoded sounds, and birds trained on pitch generalized their discrimination to harmonic sounds with a flat spectrum. These results demonstrate that, depending on the training requirements, birds can extract either fundamental frequency or spectral envelope of vowel-like sounds and use these parameters to categorize new sounds.
The amplitude of the auditory N1 component of the event‐related potential (ERP) is typically supp... more The amplitude of the auditory N1 component of the event‐related potential (ERP) is typically suppressed when a sound is accompanied by visual anticipatory information that reliably predicts the timing and identity of the sound. While this visually induced suppression of the auditory N1 is considered an early electrophysiological marker of fulfilled prediction, it is not yet fully understood whether this internal predictive coding mechanism is primarily driven by the temporal characteristics, or by the identity features of the anticipated sound. The current study examined the impact of temporal and identity predictability on suppression of the auditory N1 by visual anticipatory motion with an ecologically valid audiovisual event (a video of a handclap). Predictability of auditory timing and identity was manipulated in three different conditions in which sounds were either played in isolation, or in conjunction with a video that either reliably predicted the timing of the sound, the i...
Listeners hearing an ambiguous speech sound flexibly adjust their phonetic categories in accordan... more Listeners hearing an ambiguous speech sound flexibly adjust their phonetic categories in accordance with lipread information telling what the phoneme should be (recalibration). Here, we tested the stability of lipread-induced recalibration over time. Listeners were exposed to an ambiguous sound halfway between /t/ and /p/ that was dubbed onto a face articulating either /t/ or /p/. When tested immediately, listeners exposed to lipread /t/ were more likely to categorize the ambiguous sound as /t/ than listeners exposed to /p/. This aftereffect dissipated quickly with prolonged testing and did not reappear after a 24-hour delay. Recalibration of phonetic categories is thus a fragile phenomenon.
Humans can categorize vowels based on spectral quality (vowel identity) or pitch (speaker sex). S... more Humans can categorize vowels based on spectral quality (vowel identity) or pitch (speaker sex). Songbirds show similarities to humans with respect to speech sound discrimination and categorization, but it is unclear whether they can categorize harmonically structured vowel-like sounds on either spectrum or pitch, while ignoring the other parameter. We trained zebra finches in two experimental conditions to discriminate two sets of harmonic vowel-like sounds that could be distinguished either by spectrum or fundamental frequency (pitch). After the birds reached learning criterion, they were tested on new sounds that were either noise-vocoded versions of the trained sounds (sharing the spectral envelope with the trained sounds but lacking fine spectral detail from which pitch could be extracted) or sounds lacking the amplified harmonics (sharing only pitch with the trained sounds). Zebra finches showed no difference in the number of trials needed to learn each stimulus–response mapping. Birds trained on harmonic spectrum generalized their discrimination to vocoded sounds, and birds trained on pitch generalized their discrimination to harmonic sounds with a flat spectrum. These results demonstrate that, depending on the training requirements, birds can extract either fundamental frequency or spectral envelope of vowel-like sounds and use these parameters to categorize new sounds.
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Papers by Jean Vroomen