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Emergence of category-level sensitivities in non-native speech sound learning.

Myers EB - Front Neurosci (2014)

Bottom Line: First, where in the neural pathway does sensitivity to category-level phonetic information first emerge over the trajectory of speech sound learning?Second, how do frontal and temporal brain areas work in concert over the course of non-native speech sound learning?Finally, in the context of this literature I will describe a model of speech sound learning in which rapidly-adapting access to categorical information in the frontal lobes modulates the sensitivity of stable, slowly-adapting responses in the temporal lobes.

View Article: PubMed Central - PubMed

Affiliation: Department of Speech, Language, and Hearing Sciences, University of Connecticut Storrs, CT, USA ; Department of Psychology, University of Connecticut Storrs, CT, USA ; Haskins Laboratories New Haven, CT, USA.

ABSTRACT
Over the course of development, speech sounds that are contrastive in one's native language tend to become perceived categorically: that is, listeners are unaware of variation within phonetic categories while showing excellent sensitivity to speech sounds that span linguistically meaningful phonetic category boundaries. The end stage of this developmental process is that the perceptual systems that handle acoustic-phonetic information show special tuning to native language contrasts, and as such, category-level information appears to be present at even fairly low levels of the neural processing stream. Research on adults acquiring non-native speech categories offers an avenue for investigating the interplay of category-level information and perceptual sensitivities to these sounds as speech categories emerge. In particular, one can observe the neural changes that unfold as listeners learn not only to perceive acoustic distinctions that mark non-native speech sound contrasts, but also to map these distinctions onto category-level representations. An emergent literature on the neural basis of novel and non-native speech sound learning offers new insight into this question. In this review, I will examine this literature in order to answer two key questions. First, where in the neural pathway does sensitivity to category-level phonetic information first emerge over the trajectory of speech sound learning? Second, how do frontal and temporal brain areas work in concert over the course of non-native speech sound learning? Finally, in the context of this literature I will describe a model of speech sound learning in which rapidly-adapting access to categorical information in the frontal lobes modulates the sensitivity of stable, slowly-adapting responses in the temporal lobes.

No MeSH data available.


Related in: MedlinePlus

Perceptual warping as a consequence of phonetic category learning. (A) Schematic of the process by which categorical perception emerges through development. Top line reflects the naïve perceptual distance between tokens along an arbitrary acoustic-phonetic continuum. Over the course of development categorical information (e.g., the use of tokens to refer to minimal pairs) and the statistical distribution of tokens in acoustic-phonetic space (e.g., more tokens are heard that fall near the center of the phonetic category) converge to warp perceptual sensitivities such that between-category contrasts are more perceptually distinct than within-category contrasts. (B) Non-native speech sound training paradigms primarily rely on categorical-level cues (e.g., explicit feedback), to reshape existing sensitivities. In this particular example, a listener must learn that two non-native sounds which are typically perceived as variants of /d/ correspond to different categories. This type of learning situation presents a particular challenge to the adult learner, given that the perceptual distance between these tokens in the mature listener is collapsed. Learning may proceed either via the top-down route, (left), or via passive exposure to statistical regularities in the input (right), or both. Over time, this information likewise results in differences for within- vs. between-category perceptibility.
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Figure 1: Perceptual warping as a consequence of phonetic category learning. (A) Schematic of the process by which categorical perception emerges through development. Top line reflects the naïve perceptual distance between tokens along an arbitrary acoustic-phonetic continuum. Over the course of development categorical information (e.g., the use of tokens to refer to minimal pairs) and the statistical distribution of tokens in acoustic-phonetic space (e.g., more tokens are heard that fall near the center of the phonetic category) converge to warp perceptual sensitivities such that between-category contrasts are more perceptually distinct than within-category contrasts. (B) Non-native speech sound training paradigms primarily rely on categorical-level cues (e.g., explicit feedback), to reshape existing sensitivities. In this particular example, a listener must learn that two non-native sounds which are typically perceived as variants of /d/ correspond to different categories. This type of learning situation presents a particular challenge to the adult learner, given that the perceptual distance between these tokens in the mature listener is collapsed. Learning may proceed either via the top-down route, (left), or via passive exposure to statistical regularities in the input (right), or both. Over time, this information likewise results in differences for within- vs. between-category perceptibility.

Mentions: It is a matter of significant debate as to how categorical perception emerges. One proposal is that the statistical distribution of phonetic tokens in acoustic-phonetic space may provide sufficient information to reshape perceptual sensitivities even before functional phonetic categories have developed in the learner (Kuhl et al., 1992; Guenther and Gjaja, 1996; Maye et al., 2002, 2008). This view stems from the observation that the speech tokens that listeners are exposed to are not evenly distributed in acoustic space. For instance, the listener will hear many more examples of /t/ with a VOT near 60 ms will than with a VOT of 120 ms, although both are considered to be members of /t/ category (Figure 1A). Some evidence suggests that infant and adult listeners alike may be able to take advantage of distributional/statistical information in order to amplify acoustic distinctions that fall between different distributions and minimize those within the distribution (Maye et al., 2002, 2008; Hayes-Harb, 2007; Emberson et al., 2013). Crucially, this perceptual reshaping can happen even when listeners know nothing about the functional use of phonetic categories—that is, when listeners are only passively exposed to the input, and never hear speech sounds used referentially.


Emergence of category-level sensitivities in non-native speech sound learning.

Myers EB - Front Neurosci (2014)

Perceptual warping as a consequence of phonetic category learning. (A) Schematic of the process by which categorical perception emerges through development. Top line reflects the naïve perceptual distance between tokens along an arbitrary acoustic-phonetic continuum. Over the course of development categorical information (e.g., the use of tokens to refer to minimal pairs) and the statistical distribution of tokens in acoustic-phonetic space (e.g., more tokens are heard that fall near the center of the phonetic category) converge to warp perceptual sensitivities such that between-category contrasts are more perceptually distinct than within-category contrasts. (B) Non-native speech sound training paradigms primarily rely on categorical-level cues (e.g., explicit feedback), to reshape existing sensitivities. In this particular example, a listener must learn that two non-native sounds which are typically perceived as variants of /d/ correspond to different categories. This type of learning situation presents a particular challenge to the adult learner, given that the perceptual distance between these tokens in the mature listener is collapsed. Learning may proceed either via the top-down route, (left), or via passive exposure to statistical regularities in the input (right), or both. Over time, this information likewise results in differences for within- vs. between-category perceptibility.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4125857&req=5

Figure 1: Perceptual warping as a consequence of phonetic category learning. (A) Schematic of the process by which categorical perception emerges through development. Top line reflects the naïve perceptual distance between tokens along an arbitrary acoustic-phonetic continuum. Over the course of development categorical information (e.g., the use of tokens to refer to minimal pairs) and the statistical distribution of tokens in acoustic-phonetic space (e.g., more tokens are heard that fall near the center of the phonetic category) converge to warp perceptual sensitivities such that between-category contrasts are more perceptually distinct than within-category contrasts. (B) Non-native speech sound training paradigms primarily rely on categorical-level cues (e.g., explicit feedback), to reshape existing sensitivities. In this particular example, a listener must learn that two non-native sounds which are typically perceived as variants of /d/ correspond to different categories. This type of learning situation presents a particular challenge to the adult learner, given that the perceptual distance between these tokens in the mature listener is collapsed. Learning may proceed either via the top-down route, (left), or via passive exposure to statistical regularities in the input (right), or both. Over time, this information likewise results in differences for within- vs. between-category perceptibility.
Mentions: It is a matter of significant debate as to how categorical perception emerges. One proposal is that the statistical distribution of phonetic tokens in acoustic-phonetic space may provide sufficient information to reshape perceptual sensitivities even before functional phonetic categories have developed in the learner (Kuhl et al., 1992; Guenther and Gjaja, 1996; Maye et al., 2002, 2008). This view stems from the observation that the speech tokens that listeners are exposed to are not evenly distributed in acoustic space. For instance, the listener will hear many more examples of /t/ with a VOT near 60 ms will than with a VOT of 120 ms, although both are considered to be members of /t/ category (Figure 1A). Some evidence suggests that infant and adult listeners alike may be able to take advantage of distributional/statistical information in order to amplify acoustic distinctions that fall between different distributions and minimize those within the distribution (Maye et al., 2002, 2008; Hayes-Harb, 2007; Emberson et al., 2013). Crucially, this perceptual reshaping can happen even when listeners know nothing about the functional use of phonetic categories—that is, when listeners are only passively exposed to the input, and never hear speech sounds used referentially.

Bottom Line: First, where in the neural pathway does sensitivity to category-level phonetic information first emerge over the trajectory of speech sound learning?Second, how do frontal and temporal brain areas work in concert over the course of non-native speech sound learning?Finally, in the context of this literature I will describe a model of speech sound learning in which rapidly-adapting access to categorical information in the frontal lobes modulates the sensitivity of stable, slowly-adapting responses in the temporal lobes.

View Article: PubMed Central - PubMed

Affiliation: Department of Speech, Language, and Hearing Sciences, University of Connecticut Storrs, CT, USA ; Department of Psychology, University of Connecticut Storrs, CT, USA ; Haskins Laboratories New Haven, CT, USA.

ABSTRACT
Over the course of development, speech sounds that are contrastive in one's native language tend to become perceived categorically: that is, listeners are unaware of variation within phonetic categories while showing excellent sensitivity to speech sounds that span linguistically meaningful phonetic category boundaries. The end stage of this developmental process is that the perceptual systems that handle acoustic-phonetic information show special tuning to native language contrasts, and as such, category-level information appears to be present at even fairly low levels of the neural processing stream. Research on adults acquiring non-native speech categories offers an avenue for investigating the interplay of category-level information and perceptual sensitivities to these sounds as speech categories emerge. In particular, one can observe the neural changes that unfold as listeners learn not only to perceive acoustic distinctions that mark non-native speech sound contrasts, but also to map these distinctions onto category-level representations. An emergent literature on the neural basis of novel and non-native speech sound learning offers new insight into this question. In this review, I will examine this literature in order to answer two key questions. First, where in the neural pathway does sensitivity to category-level phonetic information first emerge over the trajectory of speech sound learning? Second, how do frontal and temporal brain areas work in concert over the course of non-native speech sound learning? Finally, in the context of this literature I will describe a model of speech sound learning in which rapidly-adapting access to categorical information in the frontal lobes modulates the sensitivity of stable, slowly-adapting responses in the temporal lobes.

No MeSH data available.


Related in: MedlinePlus