Acoustic-Emergent Phonology in the Amplitude Envelope of Child-Directed SpeechReportar como inadecuado

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When acquiring language, young children may use acoustic spectro-temporal patterns in speech to derive phonological units in spoken language e.g., prosodic stress patterns, syllables, phonemes. Children appear to learn acoustic-phonological mappings rapidly, without direct instruction, yet the underlying developmental mechanisms remain unclear. Across different languages, a relationship between amplitude envelope sensitivity and phonological development has been found, suggesting that children may make use of amplitude modulation AM patterns within the envelope to develop a phonological system. Here we present the Spectral Amplitude Modulation Phase Hierarchy S-AMPH model, a set of algorithms for deriving the dominant AM patterns in child-directed speech CDS. Using Principal Components Analysis, we show that rhythmic CDS contains an AM hierarchy comprising 3 core modulation timescales. These timescales correspond to key phonological units: prosodic stress Stress AM, ~2 Hz, syllables Syllable AM, ~5 Hz and onset-rime units Phoneme AM, ~20 Hz. We argue that these AM patterns could in principle be used by naïve listeners to compute acoustic-phonological mappings without lexical knowledge. We then demonstrate that the modulation statistics within this AM hierarchy indeed parse the speech signal into a primitive hierarchically-organised phonological system comprising stress feet proto-words, syllables and onset-rime units. We apply the S-AMPH model to two other CDS corpora, one spontaneous and one deliberately-timed. The model accurately identified 72–82% freely-read CDS and 90–98% rhythmically-regular CDS stress patterns, syllables and onset-rime units. This in-principle demonstration that primitive phonology can be extracted from speech AMs is termed Acoustic-Emergent Phonology AEP theory. AEP theory provides a set of methods for examining how early phonological development is shaped by the temporal modulation structure of speech across languages. The S-AMPH model reveals a crucial developmental role for stress feet AMs ~2 Hz. Stress feet underpin different linguistic rhythm typologies, and speech rhythm underpins language acquisition by infants in all languages.

Autor: Victoria Leong , Usha Goswami



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