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

Planet formation in Binaries

Spurred by the discovery of numerous exoplanets in multiple systems, binaries have become in recent years one of the main topics in planet formation research. Numerous studies have investigated to what extent the presence of a stellar companion can affect the planet formation process. Such studies have implications that can reach beyond the sole context of binaries, as they allow to test certain aspects of the planet formation scenario by submitting them to extreme environments. We review here the current understanding on this complex problem. We show in particular how each of the different stages of the planet-formation process is affected differently by binary perturbations. We focus especially on the intermediate stage of kilometre-sized planetesimal accretion, which has proven to be the most sensitive to binarity and for which the presence of some exoplanets observed in tight binaries is difficult to explain by in-situ formation following the "standard" planet-formation scenario. Some tentative solutions to this apparent paradox are presented. The last part of our review presents a thorough description of the problem of planet habitability, for which the binary environment creates a complex situation because of the presence of two irradation sources of varying distance.Comment: Review chapter to appear in "Planetary Exploration and Science: Recent Advances and Applications", eds. S. Jin, N. Haghighipour, W.-H. Ip, Springer (v2, numerous typos corrected

Spontaneous Voice Gender Imitation Abilities in Adult Speakers

Background The frequency components of the human voice play a major role in signalling the gender of the speaker. A voice imitation study was conducted to investigate individuals' ability to make behavioural adjustments to fundamental frequency (F0), and formants (Fi) in order to manipulate their expression of voice gender. Methodology/Principal Findings Thirty-two native British-English adult speakers were asked to read out loud different types of text (words, sentence, passage) using their normal voice and then while sounding as ‘masculine’ and ‘feminine’ as possible. Overall, the results show that both men and women raised their F0 and Fi when feminising their voice, and lowered their F0 and Fi when masculinising their voice. Conclusions/Significance These observations suggest that adult speakers are capable of spontaneous glottal and vocal tract length adjustments to express masculinity and femininity in their voice. These results point to a “gender code”, where speakers make a conventionalized use of the existing sex dimorphism to vary the expression of their gender and gender-related attributes

Phonological representation: beyond abstract versus episodic

Phonological representations capture information about individual word forms and about the general characteristics of word forms in a language. To support the processing of novel word forms as well as familiar word forms in novel contexts, an abstract level of representation is needed in which many phonetic details and contextual features are disregarded. At the same time, evidence has accumulated that such details are retained in memory and used in processing individual words and indexical features of language. Taken together, these results mean that a hybrid model of phonological representation is needed. The abstract level supports generalizations based on lexical type statistics and fast adaptation to communicative requirements through the reuse of existing categories. A richly detailed level of representation is implicated in word-specific phonetic patterns, the detailed dynamics of regular sound changes, and active associations of phonetic patterns with gender, age, and dialect

Synthesizing intonation

This paper describes a computer program for synthesizing fundamental frequency (F0) contours for English, and sketches the theory which underlies it. The F0 contour is described as a series of targets within an envelope specifying F0 range; the F0 contour between targets is computed by transition rules. The use of nonmonotonic transitions permits a sparser specification of the contour than has been possible in most previous frameworks. The program generates a good synthesis of neutral declarative intonation. Unlike most previous F0 synthesis programs, it can also be used to synthesize a variety of non‐neutral intonation patterns

Phonological representation: beyond abstract versus episodic

Phonological representations capture information about individual word forms and about the general characteristics of word forms in a language. To support the processing of novel word forms as well as familiar word forms in novel contexts, an abstract level of representation is needed in which many phonetic details and contextual features are disregarded. At the same time, evidence has accumulated that such details are retained in memory and used in processing individual words and indexical features of language. Taken together, these results mean that a hybrid model of phonological representation is needed. The abstract level supports generalizations based on lexical type statistics and fast adaptation to communicative requirements through the reuse of existing categories. A richly detailed level of representation is implicated in word-specific phonetic patterns, the detailed dynamics of regular sound changes, and active associations of phonetic patterns with gender, age, and dialect

Synthesizing intonation

This paper describes a computer program for synthesizing fundamental frequency (F0) contours for English, and sketches the theory which underlies it. The F0 contour is described as a series of targets within an envelope specifying F0 range; the F0 contour between targets is computed by transition rules. The use of nonmonotonic transitions permits a sparser specification of the contour than has been possible in most previous frameworks. The program generates a good synthesis of neutral declarative intonation. Unlike most previous F0 synthesis programs, it can also be used to synthesize a variety of non‐neutral intonation patterns