Speech recognition with reduced spectral cues as a function of age

Abstract

Adult listeners are able to recognize speech even under conditions of severe spectral degradation. To assess the developmental time course of this robust pattern recognition, speech recognition was measured in two groups of children (5-7 and 10-12 years of age) as a function of the degree of spectral resolution. Results were compared to recognition performance of adults listening to the same materials and conditions. The spectral detail was systematically manipulated using a noise-band vocoder in which filtered noise bands were modulated by the amplitude envelope from the same spectral bands in speech. Performance scores between adults and older children did not differ statistically, whereas scores by younger children were significantly lower; they required more spectral resolution to perform at the same level as adults and older children. Part of the deficit in younger children was due to their inability to utilize fully the sensory information, and part was due to their incomplete linguistic/cognitive development. The fact that young children cannot recognize spectrally degraded speech as well as adults suggests that a long learning period is required for robust acoustic pattern recognition. These findings have implications for the application of auditory sensory devices for young children with early-onset hearing loss.

Factors affecting the development of speech recognition in steady and modulated noise

“…1. The idea that the children may have required a broader frequency range than adults to recognize speech is consistent with previous research (Eisenberg et al, 2000;Mlot et al, 2010).…”

“…One purpose of the present study was to examine whether such effects were likely to be due to developmental differences in the ability to process speech information from different frequency regions, or were instead driven by speech bandwidth effects that occurred because the spectral roll-off of the masking noise was shallower than that of the speech signal. It has been previously shown that children require a wider speech bandwidth than adults to obtain comparable speech identification performance (Eisenberg et al, 2000;Mlot et al, 2010).…”

“…of performance (Eisenberg et al, 2000;Mlot et al, 2010). This larger bandwidth requirement possibly reflects a more general need for greater redundancy in the speech signal on the part of children.…”

“…In line with this, there are indications in the present and previous studies (e.g., Hall et al, 2012) that normal-hearing children can show less benefit than adults from synchronous temporal modulation of the masker, a manipulation that improves audibility of temporally sparse segments of the speech signal. As children's linguistic experience increases, tolerance for reduced speech redundancy likely also increases (e.g., Eisenberg et al, 2000;McCreery and Stelmachowicz, 2011;Mlot et al, 2010;Stelmachowicz et al, 2004).…”

Discrimination of voicing (aba vs. apa)on the basis of Envelope temporal cues in 6-month old infants

“…One study showed that in children with normal hearing, Ebased speech recognition develops before the age of 7, and becomes adult-like around 10 (for 4 to 8 bands) (Eisenberg et al, 2000). A more recent study suggests that normalhearing children are able to use such cues at adult levels by the age of 5 years in a discrimination task of phonetic contrasts (voicing, place, manner, nasality) on the basis of E or TFS information (extracted within 16 bands from original /aCa/ ).…”