Pushing the Envelope: Developments in Neural Entrainment to Speech and the Biological Underpinnings of Prosody Perception

Abstract

Prosodic cues in speech are indispensable for comprehending a speaker’s message, recognizing emphasis and emotion, parsing segmental units, and disambiguating syntactic structures. While it is commonly accepted that prosody provides a fundamental service to higher-level features of speech, the neural underpinnings of prosody processing are not clearly defined in the cognitive neuroscience literature. Many recent electrophysiological studies have examined speech comprehension by measuring neural entrainment to the speech amplitude envelope, using a variety of methods including phase-locking algorithms and stimulus reconstruction. Here we review recent evidence for neural tracking of the speech envelope and demonstrate the importance of prosodic contributions to the neural tracking of speech. Prosodic cues may offer a foundation for supporting neural synchronization to the speech envelope, which scaffolds linguistic processing. We argue that prosody has an inherent role in speech perception, and future research should fill the gap in our knowledge of how prosody contributes to speech envelope entrainment.

Infants Segment Words from Songs—An EEG Study

“…The beneficial effects of songs and music for language acquisition are generally understood in terms of both emotional-attentional and cognitive mechanisms. Musical expertise fine-tunes and enhances sensitivity to the acoustic features shared by music and speech, and it also enhances auditory attention and working memory [19][20][21][22][23][24][25][26][27][28][29]. These explanations can be extended to hypothesize that songs also provide useful linguistic input for infants.…”

“…Secondly, songs employ many features that infants are sensitive to in their early language acquisition, including phrasing [37,38] and rhythm [39,40]. Finally, it has been proposed that some of the beneficial effects of song on infants' well-being are a direct result of internal rhythmic entrainment [35], which is a mechanism that has also been hypothesized to be responsible for the improved encoding of linguistic material [27][28][29]. These three effects of song on infants render it likely that infants can effectively engage their speech encoding networks to learn from songs.…”

Advances in the Neurocognition of Music and Language

“…As argued in the review article of Reybrouck and Podlipniak [9], some of these sound features and their common preconceptual affective meanings may even reflect joint evolutionary roots of M&L that still prevail today, for example, in musical expressivity and speech prosody. Notably, a feature that was particularly central to half of all contributions is the temporal structure of M&L, i.e., the patterning of strong and weak syllables or beats that make up rhythm, meter and prosodic stress [6][7][8][10][11][12][13]15].…”

“…Current neurophysiological models assume that speech and music processing as well as the catalytic role of rhythm in language development are based on the synchronization of internal neuronal oscillations with temporally regular stimuli [27,[31][32][33]. The review article by Myers et al [15] summarizes the current state of knowledge about neuronal entrainment to the speech envelope reflecting quasi-regular amplitude fluctuations over time. This neural tracking occurs simultaneously at multiple time scales corresponding to the rates of phonemes, syllables and phrases [34,35].…”

“…If rhythmic processing disabilities are indeed the basis of speech and language disorders, then useful avenues for prevention and intervention could lie in (i) increasing the regularity of stimuli, or (ii) strengthening individual rhythmic abilities with the aim at improving neuronal entrainment [37][38][39]. Several studies in this Special Issue deal directly or indirectly with these ideas, either by exploring processing benefits of rhythmically highly regular stimuli such as songs [13,14] or poems [10,11], or by discussing potential protective or curative effects of music-based rhythm training on language skills [7,8,10,12,15,16]. Even though the results are promising, they also raise a number of questions.…”