Development of voice perception is dissociated across gender cues in school-age children

Abstract

Children's ability to distinguish speakers' voices continues to develop throughout childhood, yet it remains unclear how children's sensitivity to voice cues, such as differences in speakers' gender, develops over time. This so-called voice gender is primarily characterized by speakers' mean fundamental frequency (F0), related to glottal pulse rate, and vocal-tract length (VTL), related to speakers' size. Here we show that children's acquisition of adult-like performance for discrimination, a lower-order perceptual task, and categorization, a higher-order cognitive task, differs across voice gender cues. Children's discrimination was adult-like around the age of 8 for VTL but still differed from adults at the age of 12 for F0. Children's perceptual weight attributed to F0 for gender categorization was adult-like around the age of 6 but around the age of 10 for VTL. Children's discrimination and weighting of F0 and VTL were only correlated for 4-to 6-year-olds. Hence, children's development of discrimination and weighting of voice gender cues are dissociated, i.e., adult-like performance for F0 and VTL is acquired at different rates and does not seem to be closely related. The different developmental patterns for auditory discrimination and categorization highlight the complexity of the relationship between perceptual and cognitive mechanisms of voice perception. Voice cues enable listeners to recognize and distinguish speakers, which is imperative for speech-related tasks, such as speech perception in noisy environments. At an early age, children are already sensitive to differences in voice cues, especially for familiar speakers 1 and in their native language 2. Furthermore, infants are already sensitive to differences in voice cues, such as fundamental frequency (F0) 3 or voice pitch 4 , timbre differences associated with vocal-tract length 5 , or prosody 6. On the other hand, there is a clear prolonged development in children's ability to encode and recognize the characteristics of voices 7-9. Hence, it is unclear how children's sensitivity to differences in voice cues develops over time. Children's ability to discriminate differences in voice-related acoustic cues, such as F0 10-13 or temporal cues 14,15 , continues to develop throughout childhood. Yet, the specific age at which children's voice discrimination thresholds are adult-like has been debated, partially due to differences in experimental stimuli. Earlier research has primarily used non-voice stimuli, such as pure tones 10,11 , or octave-band 14 and narrow-band noises 15 , where the results were interpreted and extrapolated for voice perception. In contrast, research directly using voice stimuli has been scarce 12,13. Further challenges come from task demands, as these can influence outcomes, and the high variability among children's performance, even after controlling for effects of age 16. Children's ability to categorize voice and speech cues, a higher-order cognitive task, also continues to develop even after 12 years of age, e.g., as observed fo...

School-age children benefit from voice gender cue differences for the perception of speech in competing speech

“…The results showed that similarly to F0 differences, young children did not benefit from differences in speakers' VTL only, but they did benefit from a change in the two voice cues together, although this benefit was still lower than that observed in older children. This argument is also in line with the results of our previous study that indicate children weigh both F0 and VTL cues to categorize speakers' voice gender (Nagels et al, 2020a). Children may also not be sensitive enough to the acoustic variations induced by only mean F0 or only VTL differences to benefit from these during speech stream segregation and could have been relying on additional acoustic differences for speech segregation in the aforementioned studies by Leibold et al (2018) and Wightman and Kistler (2005).…”

“…For instance, the ability to segregate different speech streams based on differences in speakers' voice characteristics may help with optimally using attentional mechanisms for understanding the target speech signal better. As the ability to discriminate subtle differences in voice cues seems to develop in children during the school-age years (Buss et al, 2017a;Cleary et al, 2005;Flaherty et al, 2019;Nagels et al, 2020a), their ability to benefit from voice differences between target and masker speakers for perceiving speech in competing speech may be limited, potentially affecting further processing stages.…”

Development of vocal emotion recognition in school-age children: The EmoHI test for hearing-impaired populations

“…Our results are in line with previous findings that NH children's ability to recognize vocal emotions improves gradually as a function of age (Tonks et al, 2007;Sauter, Panattoni & Happé, 2013). It may be that children require more auditory experience to form robust representations of vocal emotions or rely on different acoustic cues than adults, as was shown in research on the development of sensitivity to voice cues (Mann, Diamond & Carey, 1979;Nittrouer & Miller, 1997;Nagels et al, 2020). It is still unclear on which specific acoustic cues children are basing their decisions on and how this differs from adults.…”

“…NH and CI children were tested in a quiet room at their home, and NH adults were tested in a quiet testing room at the two universities. Since the present experiment was part of a larger project on voice and speech perception (Perception of Indexical Cues in Kids and Adults (PICKA)), data were collected from the same population of children and adults in multiple experiments, see, for instance, Nagels et al (2020). The experiment started with a training session consisting of 4 practice stimuli and was followed by the test session consisting of 36 experimental stimuli.…”

Rethinking the frequency code: a meta-analytic review of the role of acoustic body size in communicative phenomena

“…[34][35][36]). Despite this cultural and individual variation, listeners are highly sensitive to the distinction between male and female voices, a skill that arises early but continues to develop throughout one's lifetime [37]. Evidence from auditory Stroop tasks with male and female voices shows that people automatically process the speaker's gender even when this information is task irrelevant [38].…”