804 research outputs found
Brittany Bernal - Sensorimotor Adaptation of Vowel Production in Stop Consonant Contexts
The purpose of this research is to measure the compensatory and adaptive articulatory response to shifted formants in auditory feedback to compare the resulting amount of sensorimotor learning that takes place in speakers upon saying the words /pep/ and /tet/. These words were chosen in order to analyze the coarticulatory effects of voiceless consonants /p/ and /t/ on sensorimotor adaptation of the vowel /e/. The formant perturbations were done using the Audapt software, which takes an input speech sample and plays it back to the speaker in real-time via headphones. Formants are high-energy acoustic resonance patterns measured in hertz that reflect positions of articulators during the production of speech sounds. The two lowest frequency formants (F1 and F2) can uniquely distinguish among the vowels of American English. For this experiment, Audapt shifted F1 down and F2 up, and those who adapt were expected to shift in the opposite direction of the perturbation. The formant patterns and vowel boundaries were analyzed using TF32 and S+ software, which led to conclusions about the adaptive responses. Manipulating auditory feedback by shifting formant values is hypothesized to elicit sensorimotor adaptation, a form of short-term motor learning. The amount of adaptation is expected to be greater for the word /pep/ rather than /tet/ because there is less competition for articulatory placement of the tongue during production of bilabial consonants. This methodology could be further developed to help those with motor speech disorders remedy their speech errors with much less conscious effort than traditional therapy techniques.https://epublications.marquette.edu/mcnair_2013/1008/thumbnail.jp
Top-down effects on compensation for coarticulation are not replicable
Listeners use lexical knowledge to judge what speech sounds they heard. I investigated whether such lexical influences are truly top-down or just reflect a merging of perceptual and lexical constraints. This is achieved by testing whether the lexically determined identity of a phone exerts the appropriate context effects on surrounding phones. The current investigations focuses on compensation for coarticulation in vowel-fricative sequences, where the presence of a rounded vowel (/y/ rather than /i/) leads fricatives to be perceived as /s/ rather than /∫/. This results was consistently found in all three experiments. A vowel was also more likely to be perceived as rounded /y/ if that lead listeners to be perceive words rather than nonwords (Dutch: meny, English id. vs. meni nonword). This lexical influence on the perception of the vowel had, however, no consistent influence on the perception of following fricative.peer-reviewe
On the causes of compensation for coarticulation : evidence for phonological mediation
This study examined whether compensation for coarticulation in fricative-vowel syllables is phonologically mediated or a consequence of auditory processes. Smits (2001a) had shown that compensation occurs for anticipatory lip rounding in a fricative caused by a following rounded vowel in Dutch. In a first experiment, the possibility that compensation is due to general auditory processing was investigated using nonspeech sounds. These did not cause context effects akin to compensation for coarticulation, although nonspeech sounds influenced speech sound identification in an integrative fashion. In a second experiment, a possible phonological basis for compensation for coarticulation was assessed by using audiovisual speech. Visual displays, which induced the perception of a rounded vowel, also influenced compensation for anticipatory lip rounding in the fricative. These results indicate that compensation for anticipatory lip rounding in fricative-vowel syllables is phonologically mediated. This result is discussed in the light of other compensation-for-coarticulation findings and general theories of speech perception.peer-reviewe
Perceptual compensation in individuals with autism spectrum disorders
Compensation for coarticulation is the extent in which an individual perceives the contextual variations of speech. When presented with an ambiguous consonant-vowel segment (e.g., a consonant halfway between /sa/ and /∫a/) research illustrates that a listener is likely to compensate for coarticulation with the following vowel. Therefore, a listener will be more likely to report an ambiguous speech sound as /s/ when it occurs before [u] than before [a]. Previous results have suggested that, within neurotypical individuals, the degree to which individuals compensate for coarticulation may be related to their Autism Quotient (AQ; Yu, 2010). However, this research did not examine individuals with an autism spectrum disorder (ASD). The current study extends this research by exploring compensation for coarticulation in individuals with an ASD as compared to neurotypical peers in a phoneme classification task (labeling an ambiguous phoneme as either /s/ or /∫/). Results from a generalized linear mixed effect model suggest that while there are no differences in how the clinical and neurotypical population compensate for coarticulation, there is a difference in how these two cohorts categorize phonemes. Individuals with an ASD illustrate a gradient categorization slope, while neurotypical individuals show a categorical response curve
Robust Lexically Mediated Compensation for Coarticulation: Christmash Time Is Here Again
First published: 20 April 2021A long-standing question in cognitive science is how high-level knowledge is integrated with sensory
input. For example, listeners can leverage lexical knowledge to interpret an ambiguous speech
sound, but do such effects reflect direct top-down influences on perception or merely postperceptual
biases? A critical test case in the domain of spoken word recognition is lexically mediated compensation
for coarticulation (LCfC). Previous LCfC studies have shown that a lexically restored context
phoneme (e.g., /s/ in Christma#) can alter the perceived place of articulation of a subsequent target
phoneme (e.g., the initial phoneme of a stimulus from a tapes-capes continuum), consistent with the
influence of an unambiguous context phoneme in the same position. Because this phoneme-to-phoneme
compensation for coarticulation is considered sublexical, scientists agree that evidence for LCfC would
constitute strong support for top–down interaction. However, results from previous LCfC studies have
been inconsistent, and positive effects have often been small. Here, we conducted extensive piloting of
stimuli prior to testing for LCfC. Specifically, we ensured that context items elicited robust phoneme
restoration (e.g., that the final phoneme of Christma# was reliably identified as /s/) and that unambiguous
context-final segments (e.g., a clear /s/ at the end of Christmas) drove reliable compensation for
coarticulation for a subsequent target phoneme.We observed robust LCfC in a well-powered, preregistered
experiment with these pretested items (N = 40) as well as in a direct replication study (N = 40).
These results provide strong evidence in favor of computational models of spoken word recognition
that include top–down feedback
Compensation for complete assimilation in speech perception: The case of Korean labial-to-velar assimilation
In connected speech, phonological assimilation to neighboring words can lead to pronunciation variants (e.g., 'garden bench'→ "gardem bench"). A large body of literature suggests that listeners use the phonetic context to reconstruct the intended word for assimilation types that often lead to incomplete assimilations (e.g., a pronunciation of "garden" that carries cues for both a labial [m] and an alveolar [n]). In the current paper, we show that a similar context effect is observed for an assimilation that is often complete, Korean labial-to-velar place assimilation. In contrast to the context effects for partial assimilations, however, the context effects seem to rely completely on listeners' experience with the assimilation pattern in their native language
Recognizing Speech in a Novel Accent: The Motor Theory of Speech Perception Reframed
The motor theory of speech perception holds that we perceive the speech of
another in terms of a motor representation of that speech. However, when we
have learned to recognize a foreign accent, it seems plausible that recognition
of a word rarely involves reconstruction of the speech gestures of the speaker
rather than the listener. To better assess the motor theory and this
observation, we proceed in three stages. Part 1 places the motor theory of
speech perception in a larger framework based on our earlier models of the
adaptive formation of mirror neurons for grasping, and for viewing extensions
of that mirror system as part of a larger system for neuro-linguistic
processing, augmented by the present consideration of recognizing speech in a
novel accent. Part 2 then offers a novel computational model of how a listener
comes to understand the speech of someone speaking the listener's native
language with a foreign accent. The core tenet of the model is that the
listener uses hypotheses about the word the speaker is currently uttering to
update probabilities linking the sound produced by the speaker to phonemes in
the native language repertoire of the listener. This, on average, improves the
recognition of later words. This model is neutral regarding the nature of the
representations it uses (motor vs. auditory). It serve as a reference point for
the discussion in Part 3, which proposes a dual-stream neuro-linguistic
architecture to revisits claims for and against the motor theory of speech
perception and the relevance of mirror neurons, and extracts some implications
for the reframing of the motor theory
Cross-language Differences in Fricative Processing and Their Influence on Non-native Fricative Categorisation
Studies have shown that native speakers of Mandarin Chinese and Hong Kong Cantonese tend to have difficulty perceiving the English fricative /θ/. However, although both languages have /f/ and /s/ categories, Mandarin speakers tend to assimilate it to their /s/ category whilst Cantonese speakers would assimilate it to their /f/ category. Over three studies, this thesis investigated various factors that may lead to this difference, while enhancing our understanding of the acoustics and the perception of the fricatives of these languages. Study 1 explored acoustic properties of target fricatives of the three languages (Mandarin, Cantonese, English) using audio recordings from native speakers, and conducted comparisons of the fricatives within and across languages. The results showed that the phonemes /f s/, even though shared by the three languages, were produced differently in the different languages, likely due to the effects of the different fricative inventories. Moreover, different acoustic cues were more or less effective in distinguishing between the different fricatives in each language, indicating that native speakers of these languages likely rely on these cues differently. Study 2 examined how transition cues may affect the identification of /f/ and /s/ by native speakers of the respective languages by combining a phoneme monitoring task and EEG measures. Target fricatives were spliced with vowels to create stimuli with congruent or incongruent transitions. In contrast to previous studies (e.g., Wagner, Ernestus & Cutler, 2006), the results revealed that all groups attended to formant transitions when processing fricatives, despite their differing native fricative inventory sizes. Study 3 investigated cross-language differences in categorisation boundaries of target fricative pairs using a behavioural identification task. The study interpolated pairs of stimuli to create a frication continuum and a vowel continuum, forming a 2-dimensional stimuli grid. The results indicated that frication was the primary cue for fricative identification for the native English, Cantonese, and Mandarin speakers, but also revealed cross-language differences in fricative boundaries. Overall, the results of these studies demonstrate that the processing of fricatives was largely driven by the frication section, and the differential assimilation of /θ/ was likely due to the different acoustics of the same fricative category across languages. The results also motivate a reconsideration of the role of coarticulatory cues in fricative perception
The time course of auditory and language-specific mechanisms in compensation for sibilant assimilation
Models of spoken-word recognition differ on whether compensation for assimilation is language-specific or depends on general auditory processing. English and French participants were taught words that began or ended with the sibilants /s/ and /∫/. Both languages exhibit some assimilation in sibilant sequences (e.g., /s/ becomes like [∫] in dress shop and classe chargée), but they differ in the strength and predominance of anticipatory versus carryover assimilation. After training, participants were presented with novel words embedded in sentences, some of which contained an assimilatory context either preceding or following. A continuum of target sounds ranging from [s] to [∫] was spliced into the novel words, representing a range of possible assimilation strengths. Listeners' perceptions were examined using a visual-world eyetracking paradigm in which the listener clicked on pictures matching the novel words. We found two distinct language-general context effects: a contrastive effect when the assimilating context preceded the target, and flattening of the sibilant categorization function (increased ambiguity) when the assimilating context followed. Furthermore, we found that English but not French listeners were able to resolve the ambiguity created by the following assimilatory context, consistent with their greater experience with assimilation in this context. The combination of these mechanisms allows listeners to deal flexibly with variability in speech forms
Selective Adaptation in Speech: Measuring the Effects of Visual and Lexical Contexts
Published Aug 1, 2021Speech selective adaptation is a phenomenon in which repeated presentation of a speech stimulus alters
subsequent phonetic categorization. Prior work has reported that lexical, but not multisensory, context
influences selective adaptation. This dissociation suggests that lexical and multisensory contexts influence
speech perception through separate and independent processes (see Samuel & Lieblich, 2014).
However, this dissociation is based on results reported by different studies using different stimuli. This
leaves open the possibility that the divergent effects of multisensory and lexical contexts on selective
adaptation may be the result of idiosyncratic differences in the stimuli rather than separate perceptual
processes. The present investigation used a single stimulus set to compare the selective adaptation produced
by lexical and multisensory contexts. In contrast to the apparent dissociation in the literature, we
find that multisensory information can in fact support selective adaptation.Support for this project was provided by NSF Grant 1632530 to
Lawrence D. Rosenblum as well as the Spanish Ministry of Science and
Innovation, Grant PSI2017-82563-P, awarded to Arthur G. Samuel and
was partially supported by the Basque Government through the BERC
2018-2021 program, and by the Spanish State Research Agency through
BCBL Severo Ochoa excellence accreditation SEV-2015-0490 awarded to
Arthur G. Samuel
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