Acoustic parameters for the three CDS corpora used for PCA analysis (Corpus 1) and for model evaluation (Corpora 2 & 3).

<p>Each cell shows the mean value across all speakers, with the standard deviation across speakers in brackets below. Note that the speakers of Corpora 1 & 3 are all female, but Corpus 2 included 1 male speaker.</p

List of 20 untimed nursery rhyme sentences, each 24 syllables long.

<p>List of 20 untimed nursery rhyme sentences, each 24 syllables long.</p

Prosodic templates for metronome-timed sentences in Corpus 2.

<p>Prosodic templates for metronome-timed sentences in Corpus 2.</p

Signal processing steps prior to Spectral PCA.

<p>The original acoustic signal (a) is passed through an ERB_N-spaced filterbank, yielding a set of high-dimensional spectral channel outputs (b). The envelope is extracted from each spectral channel output using the Hilbert transform (c), and these envelopes are entered into the spectral PCA to identify patterns of covariation across spectral channels.</p

Spectral PCA loading patterns for CDS corpora (7a, top) and white noise surrogates (7b, bottom).

<p><b>(7a)</b> (Left y-axis) Grand average rectified loadings for the top 5 principal components arising from the Spectral PCA of the CDS corpora, averaged across all speech samples from 6 speakers. The blue diamonds mark peaks in loading and the red dots mark troughs in loading. On the basis of these peak and trough patters (see text), 5 spectral bands are inferred, whose boundaries are shown as vertical dotted lines. (Right y-axis) Grand average correlation coefficient between each spectral channel and all the other spectral channels, plotted as a dotted green line. (7b) Grand average rectified loadings for the top 5 principal components arising from the Spectral PCA of white noise surrogates of the CDS corpora, averaged across all speech samples from 6 speakers. Note that there is no systematic pattern of peaks.</p

Acoustic waveforms and corresponding Syllable AMs for 4 different CVC syllables.

<p>The syllables are: "cap" (top left), "map" (top right), "nib" (bottom left) and "pan" (bottom right). For each word, its acoustic waveform is shown in black, and the Syllable AMs from spectral bands 2,3 & 4 are overlaid as coloured lines. The vertical dotted lines in each plot indicate the manually-located boundaries between the onset, vowel nucleus and coda. Note that for each word, the highest Syllable AM peak (point of greatest energy) falls within the vowel nucleus, as indicated with black dots. However, the spectral band with the highest Syllable AM peak varies across words. For example, for "cap" and "map", it is spectral band 3 (700–1750 Hz, green) which carries the strongest peak. For "nib" and "pan", it is spectral band 2 (300–700 Hz, red) which carries the strongest peak.</p

Example of the 5x3 spectro-temporal representation of speech modulation structure.

<p>(Left column) Original acoustic waveform for the word "pan". (Middle column) 5-spectral band filtered signal with Hilbert envelopes from each spectral band overlaid in bold. (Right column) Final 5x3 spectro-temporal representation. 3 modulation rate bands (Stress, Syllable & Phoneme) are extracted from each of the envelopes in the 5 spectral bands. Each modulation rate band is plotted in a different colour.</p

Summary of the 3 modulation rate bands indentified from PCA.

<p>Summary of the 3 modulation rate bands indentified from PCA.</p

Peak and trough locations for PC1-PC3.

<p>Peak and trough locations for PC1-PC3.</p

28 spectral-channel (high-dimensional) envelope representation of the nursery rhyme sentence "Twinkle twinkle little star".

<p>The bottom panel (grey) shows the original sound pressure waveform of the sentence, where the x-axis indicates time and the y-axis indicates signal amplitude. The top panel shows the corresponding high-dimensional set of 40 Hz low-pass filtered Hilbert envelopes. The envelopes for the 28 ERB_N-spaced spectral channels are plotted upwards in order of increasing acoustic frequency, where each coloured line indicates a different spectral channel (i.e. blue = low frequency, red = high frequency). The vertical height of each coloured line indicates the amplitude of the envelope at each point in time.</p