The development of relative amplitude changes across acoustic discontinuities in nasal+vowel syllables

In adult productions of nasal+vowel syllables, relative amplitude changes occur in various frequency regions across acoustic discontinuities and provide important cues as to the place of articulation of nasal consonants. The purpose of this study was to investigate the development of relative amplitude changes in children as potential acoustic correlates to place of articulation. Four age groups of eight participants each (3, 5, 7, adult) served as speakers. Participants produced five productions each of CV syllables comprised of [m] and [n] in the context of four vowels ([i æ u ■]). These syllables were segmented into approximately 25 ms segments of the murmur and 25 ms segments of the vowel bordering the period of discontinuity. The relative amplitude changes in low- and high-frequency ranges from the murmur to the vowel were determined using summed amplitude information from fast Fourier transform (FFT) analyses. Previous research showed systematic differences in relative amplitude between [m] and [n] in adult syllable productions, but only marginal differences were observed in very young children’s speech. The relative amplitude property, a landmark cue representing place of articulation of nasal consonants, is predicted to develop with age based on these preliminary analyses. [Work supported by NIH and an ASHA SPARC Award.]