Converging toward a common speech code: imitative and perceptuo-motor recalibration processes in speech production

Abstract

Auditory and somatosensory systems play a key role in speech motor control. In the act of speaking, segmental speech movements are programmed to reach phonemic sensory goals, which in turn are used to estimate actual sensory feedback in order to further control production. The adult's tendency to automatically imitate a number of acoustic-phonetic characteristics in another speaker's speech however suggests that speech production not only relies on the intended phonemic sensory goals and actual sensory feedback but also on the processing of external speech inputs. These online adaptive changes in speech production, or phonetic convergence effects, are thought to facilitate conversational exchange by contributing to setting a common perceptuo-motor ground between the speaker and the listener. In line with previous studies on phonetic convergence, we here demonstrate, in a non-interactive situation of communication, online unintentional and voluntary imitative changes in relevant acoustic features of acoustic vowel targets (fundamental and first formant frequencies) during speech production and imitation. In addition, perceptuo-motor recalibration processes, or after-effects, occurred not only after vowel production and imitation but also after auditory categorization of the acoustic vowel targets. Altogether, these findings demonstrate adaptive plasticity of phonemic sensory-motor goals and suggest that, apart from sensory-motor knowledge, speech production continuously draws on perceptual learning from the external speech environment.

Sensory-motor relationships in speech production in post-lingually deaf cochlear-implanted adults and normal-hearing seniors: Evidence from phonetic convergence and speech imitation

“…We firstly replicated the previous findings by Sato et al (2013) and Garnier et al (2013) for young 369 adults with normal hearing. Imitative changes towards the acoustic target were indeed observed in 370 both tasks, with stronger convergence in the task with direct instruction than in the convergence task.…”

“…Indeed, unintentional imitation, or 75 production of auditorily presented words without interaction, and they also reported offline adaptation 90 to the auditory targets in post-tests following stimulus exposure. These studies hence suggest that 91 phonetic convergence is not only a matter of social attunement, but could also involve a more basic 92 stage of continuous automatic adaptation of the speech production system to the external speech 93 sounds environment (for a recent review, see Sato et al, 2013). 94…”

Please say what this word is—Vowel-extrinsic normalization in the sensorimotor control of speech.

“…In particular, convergence effects involving vowel formants have been inconsistent among studies, with some showing convergence (e.g., Babel, 2012; Sato et al ., 2013) and others showing divergence or mixed changes in vowel formant patterns across talkers under varying conditions (Pardo, 2013). Furthermore, while several studies have demonstrated convergence effects under conditions of non-interactive word presentation (e.g., Goldinger, 1998; Sato et al ., 2013; Shockley et al ., 2004), psycho-social variables such as attractiveness (Babel, 2012), social closeness (Pardo et al ., 2012), conversational role and gender (Pardo, 2006) have been shown to modulate the degree of convergence across a range of acoustic parameters. In the present study, participants did not engage in a conversational interaction, but rather were passively exposed to a brief sample of another talker’s speech prior to speaking (and notably, that exposure did not include the target word).…”

“…Interestingly, such an explanation for speech accommodation (or convergence) has, to our knowledge, not previously been discussed. While some researchers have proposed a purely sensorimotor mechanism to explain phonetic convergence, it has been framed as a shift in phonetic targets toward the model provided by an interlocutor (e.g., Sato et al ., 2013). The mechanism suggested by the present result, in contrast, is purely perceptual in nature.…”

Role of imitation in the emergence of phonological systems

“…in speakers who have reached the full mastery of their native language. Empirical evidences of phonetic convergence have accumulated over the last decade, whether in laboratory settings exposing a speaker to another individual's speech productions (Namy et al, 2002;Goldinger & Azuma, 2004;Shockley et al, 2004;Delvaux & Soquet, 2007;Nielsen, 2011;Babel, 2010Babel, , 2012Babel & Bulatov, 2012;Gentilucci & Bernadis, 2007;Honorof et al, 2011;Miller et al, 2013;Mitterer & Ernestus, 2008;Yu et al, 2013;Dufour & Nguyen, 2013;Lelong & Bailly, 2011;Lelong, 2012;Nguyen et al, 2012;Sato et al, 2013), or in actual conversational interactions (Pardo, 2006;Pardo et al, 2010;Kim et al, 2011;Aubanel, 2011) but the exact role of phonetic convergence in speech and language remains an open question. Still, phonetic convergence may inform us on how speech sounds are dealt with, i.e.…”