Can you hear my age? Influences of speech rate and speech spontaneity on estimation of speaker age

Abstract

Cognitive hearing science is mainly about the study of how cognitive factors contribute to speech comprehension, but cognitive factors also partake in speech processing to infer non-linguistic information from speech signals, such as the intentions of the talker and the speaker's age. Here, we report two experiments on age estimation by "naïve" listeners. The aim was to study how speech rate influences estimation of speaker age by comparing the speakers' natural speech rate with increased or decreased speech rate. In Experiment 1, listeners were presented with audio samples of read speech from three different speaker age groups (young, middle aged, and old adults). They estimated the speakers as younger when speech rate was faster than normal and as older when speech rate was slower than normal. This speech rate effect was slightly greater in magnitude for older (60-65 years) speakers in comparison with younger (20-25 years) speakers, suggesting that speech rate may gain greater importance as a perceptual age cue with increased speaker age. This pattern was more pronounced in Experiment 2, in which listeners estimated age from spontaneous speech. Faster speech rate was associated with lower age estimates, but only for older and middle aged (40-45 years) speakers. Taken together, speakers of all age groups were estimated as older when speech rate decreased, except for the youngest speakers in Experiment 2. The absence of a linear speech rate effect in estimates of younger speakers, for spontaneous speech, implies that listeners use different age estimation strategies or cues (possibly vocabulary) depending on the age of the speaker and the spontaneity of the speech. Potential implications for forensic investigations and other applied domains are discussed.

Keywords: age estimation; cognitive speech processing; speech perception; speech rate; speech spontaneity.

FIGURE 1

Age estimation in Experiment 1 calculated as the average of the signed differences between the age estimations and chronological age of the speakers. The estimates are made of voices from young, middle aged and old speakers based on recordings of read speech that are either played back at a neutral rate (same as the recording), a faster rate (10% faster), or a slower rate (10% slower). Error bars represent SEMs.

FIGURE 2

Age estimation in Experiment 1 calculated as the percent error estimate (the average of the signed differences between the age estimations and chronological age of the speakers, divided with speakers age). The estimates are made of voices from young, middle aged, and old speakers based on recordings of read speech that are either played back at a neutral rate (same as the recording), a faster rate (10% faster) or a slower rate (10% slower). Error bars represent SEMs.

FIGURE 3

Age estimation in Experiment 2 calculated as the average of the signed differences between the age estimations and chronological age of the speakers. The estimates are made of voices from young, middle aged, and old speakers based on recordings of spontaneous speech that are either played back at a neutral rate (same as the recording), a faster rate (10% faster) or a slower rate (10% slower). Error bars represent SEMs.

FIGURE 4

Age estimation in Experiment 2 calculated as the percent error estimate (the average of the signed differences between the age estimations and chronological age of the speakers, divided with speakers age). The estimates are made of voices from young, middle aged, and old speakers based on recordings of read speech that are either played back at a neutral rate (same as the recording), a faster rate (10% faster) or a slower rate (10% slower). Error bars represent SEMs.

FIGURE 5

Age estimation accuracy in Experiment 1 (read speech) and Experiment 2 (spontaneous speech). Note that lower values represent higher accuracy, as accuracy is calculated as the average of the absolute values of the difference between the age estimations and chronological age of the speakers. The estimates are made of voices from young, middle aged, and old speakers based on read speech and spontaneous speech played back at a neutral rate (same as the recording). Error bars represent SEMs.