Near‐term fetuses process temporal features of speech

Abstract

The perception of speech and music requires processing of variations in spectra and amplitude over different time intervals. Near-term fetuses can discriminate acoustic features, such as frequencies and spectra, but whether they can process complex auditory streams, such as speech sequences and more specifically their temporal variations, fast or relatively slow acoustic variations, is unclear. We recorded the cardiac activity of 82 near-term fetuses (38 weeks GA) in quiet sleep during a silent control condition and four 15 s streams presented at 90 dB SPL Leq: two piano melodies with opposite contours, a natural Icelandic sentence and a chimera of the sentence--all its spectral information was replaced with broadband noise, leaving its specific temporal variations in amplitude intact without any phonological information. All stimuli elicited a heart rate deceleration. The response patterns to the melodies were the same and differed significantly from those observed with the Icelandic sentence and its chimera, which did not differ. The melodies elicited a monophasic heart rate deceleration, indicating a stimulus orienting reflex while the Icelandic and its chimera evoked a sustained lower magnitude response, indicating a sustained attentional response or more focused information processing. A conservative interpretation of the data is that near-term fetuses can perceive sound streams and the rapid temporal variations in amplitude that are specific to speech sounds with no spectral variations at all.

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“…A seminal study (DeCasper & Fifer, 1980) provided initial evidence that fetuses learn to recognize their mother’s voice and refinements revealed neonatal preferences for the filtered maternal voice that more closely approximates the intrauterine environment (Spence & DeCasper, 1987), prefer voices spoken in their native language (Moon, Lagercrantz, & Kuhl, 2013; Moon, Panneton, & Fifer, 1993), and can discriminate between familiar and non-familiar words (Partanen, Kujala, Naatanen, et al, 2013). Studies conducted with the fetus, based on discerning fairly small heart rate or motor responses to various stimuli, provide support for the prenatal capacity to differentiate among stimulus properties, including speech sounds (DeCasper, Lecanuet, Busnel, Granier-Deferre, & Maugeais, 1994; Granier-Deferre, Ribeiro, Jacquet, & Bassereau, 2011; Hepper, Scott, & Shahidullah, 1993; Lecanuet et al, 1992). We have reported that changes in fetal heart rate and motor activity to maternal reading aloud (Cohort VIII) appear to be a response to variation in normal maternal speech patterns which were partially dependent on whether women had been previously speaking naturally (Voegtline, DiPietro, Costigan, & Pater, 2013).…”

Rhythm perception, production, and synchronization during the perinatal period

“…Thus, rhythm seems to again play a role here. In further support of this idea, it is interesting to note that near-term fetuses are not able to discriminate two piano melodies presenting the same tempo and the same rhythm, even if the melodies have opposite contours (Granier-Deferre et al, 2011). Similarly, the same fetuses are not able to discriminate two sentences, one in Icelandic and another its chimera, with both having exactly the same sequence of rapid and slow temporal amplitude variations over time, but not having the same phonological information.…”

“…The authors concluded that the fetus can learn to recognize music. In another study, near term fetuses were shown to discriminate between two low-pitched musical notes (Lecanuet et al, 2000) and to recognize a 600 ms inter-onset interval of an isochronous sequence of musical notes from a 10% faster or slower isochronous sequence (Lecanuet, Jacquet and Bontemps, cited in Granier-Deferre et al, 2011). Kisilevsky et al (2004) also observed an overall HR deceleration in near term fetuses when they listened to a 5 min Brahms’ lullaby, regardless of the sound levels tested (95, 100, 105, or 110 dB).…”

Perspectives on the rhythm–grammar link and its implications for typical and atypical language development

“…Human infants exhibit sensitivity to aspects of prosody that are available prenatally (temporal envelope cues 9 ); prosodic sensitivity becomes ever-more refined during the first year of life, and such sensitivity may provide language learners with a robust mechanism for processing linguistic input across the life span. Prosodic regularity facilitates memory of novel syllable pairs, 10 word segmentation, 11 word recognition, 12 word-form learning, 13 and fluent reading comprehension.…”