The Effect of Ageing on Speech Rhythm: A Study on Zurich German

Abstract

Speech segmental and suprasegmental characteristics vary considerably across the life span, for example, due to degenerative changes in speech production mechanisms and neuro-muscolar control. A great deal of research on the acoustic correlates of adult speakers' voice has focussed on changes in voice quality, vowel formant patterns, f0, amplitude and speech rate. Only little attention has been paid on speech rhythm variability due to advancing age. Here we quantified between-language rhythmic variability in terms of the durational characteristics of consonantal and vocalic intervals (henceforth CV intervals). We compared the segmental durational variability of two groups of Zurich German speakers. Group 1: 16 young adults, aged from 18 to 32 years; group 2: 10 older adults, aged from 66 to 81 years. For both groups we analyzed 20 sentences in Zurich German from the TEVOID Corpus. Between-speaker durational variability across age was quantified through a variety of interval-based metrics: segment rate, %V, deltaC, deltaV, VarcoC, VarcoV, rPVI-C and nPVI-V. Results showed that rhythmic differences between younger and older adults are largely accountable for by speech rate differences. Segment rate, %V and raw measures of CV interval durational variability (deltaV, deltaC and r-PVI-C) showed effects between younger and older adults. Rate normalized metrics (VarcoC, VarcoV and n-PVI-V) did not differ significantly between the two age-groups. AbstractSpeech segmental and suprasegmental characteristics vary considerably across the life span, for example, due to degenerative changes in speech production mechanisms and neuro-muscolar control. A great deal of research on the acoustic correlates of adult speakers' voice has focussed on changes in voice quality, vowel formant patterns, f0, amplitude and speech rate. Only little attention has been paid on speech rhythm variability due to advancing age.Here we quantified age-related rhythmic variability in terms of the durational characteristics of consonantal and vocalic intervals (henceforth CV intervals). We compared the segmental durational variability of two groups of Zurich German speakers. Group 1: 16 young adults, aged from 18 to 32 years; group 2: 10 older adults, aged from 66 to 81 years. For both groups we analyzed 20 sentences in Zurich German from the TEVOID Corpus. Between-speaker durational variability across age was quantified through a variety of interval-based metrics: segment rate, %V, deltaC, deltaV, VarcoC, VarcoV, rPVI-C and nPVI-V.Results showed that rhythmic differences between younger and older adults are largely accountable for by speech rate differences. Segment rate, %V and raw measures of CV interval durational variability (deltaV, deltaC and r-PVI-C) showed effects between younger and older adults. Rate normalized metrics (VarcoC, VarcoV and n-PVI-V) did not differ significantly between the two age-groups.

The effect of healthy aging on within-speaker rhythmic variability: A case study on Noam Chomsky

“…Based on this, we might tentatively interpret the reduced segment/ vowel and consonant rate in Chomsky' speech in view of his attempt to keep his pronunciation clear while giving public speeches. While the general decrease in speech rate with advancing age is in line with previous research on vocal aging and age-related rhythmic variability (Pellegrino, He, & Dellwo, 2018;Pettorino, Pellegrino, & Maffia, 2014), the findings related to %V are more controversial. If in the above mentioned crosssectional and longitudinal studies in Italian and Swiss German, it was shown that with advancing age %V significantly increased but the durational characteristics of CV intervals remained comparable, in Chomsky's corpus we found an opposite trend: no effect of recording year for %V and %Vn, but a main effect for PVI-V, although none of the post hoc comparisons reach the significance level ( Figure 5).…”

“…The results confirmed the increase in %V in the aged voices found in the longitudinal study. A similar pattern was found in a crosssectional study comparing the performance of 16 younger adults (aged between 18 and 31) and 10 older adults (aged between 65 and 81), reading aloud 20 sentences in Zurich German with equivalent lexical content (Pellegrino, He, & Dellwo, 2018). It was found that older adults typically speak more slowly, and present higher %V, deltaV and del-taC than younger adults, but the two groups are comparable in terms of the durational characteristics of CV intervals when these are normalized for speech rate.…”

Age-related rhythmic variations : The role of syllable intensity variability

“…We also explored whether there was a dependency between age-related temporal and syllable intensity variability, by correlating mean and peak syllable intensity measures (VarcoIμ, nPVI-Iμ, VarcoIp and nPVI-Ip) with %V. Among the numerous rhythmic measures based on the temporal characteristics of CV intervals, we selected precisely %V since this has been proven to change significantly as a function of age (e.g., Pellegrino & Pettorino 2014;Pellegrino et al 2018), but very limitedly as a function of speech rate (e.g., Dellwo & Wagner 2003;Dellwo 2006).…”

“…Among the various models, existing research on age-related rhythmic changes has predominantly focussed on consonantal and vocalic intervals' durational variability. Cross-sectional studies on Italian and Zurich German suggest that the speech of older adults is characterised by lower speech rate, higher proportion over which speech is vocalic (%V), and higher variability of consonantal and vocalic interval durations (henceforth: CV interval) (Pettorino & Pellegrino 2014;Pellegrino et al 2018). Nevertheless, it was mainly speech rate that accounted for these results, because the effect of age disappeared when the rhythmic variables were normalized for speech rate (Pellegrino et al 2018).…”

“…Cross-sectional studies on Italian and Zurich German suggest that the speech of older adults is characterised by lower speech rate, higher proportion over which speech is vocalic (%V), and higher variability of consonantal and vocalic interval durations (henceforth: CV interval) (Pettorino & Pellegrino 2014;Pellegrino et al 2018). Nevertheless, it was mainly speech rate that accounted for these results, because the effect of age disappeared when the rhythmic variables were normalized for speech rate (Pellegrino et al 2018). Since longitudinal data on large time-span ageing are difficult to obtain, there is little evidence on within-subject rhythmic variability.…”