Extended high-frequency hearing and head orientation cues benefit children during speech-in-speech recognition

While the audible frequency range for humans spans approximately 20 Hz to 20 kHz, children display enhanced sensitivity relative to adults when detecting extended high frequencies (frequencies above 8 kHz; EHFs), as indicated by better pure tone thresholds. The impact that this increased hearing sensitivity to EHFs may have on children's speech recognition has not been established. One context in which EHF hearing may be particularly important for children is when recognizing speech in the presence of competing talkers. In the present study, we examined the extent to which school-age children (ages 5-17 years) with normal hearing were able to benefit from EHF cues when recognizing sentences in a two-talker speech masker. Two filtering conditions were tested: all stimuli were either full band or were low-pass filtered at 8 kHz to remove EHFs. Given that EHF energy emission in speech is highly dependent on head orientation of the talker (i.e., radiation becomes more directional with increasing frequency), two masker head angle conditions were tested: both co-located maskers were facing 45°, or both were facing 60° relative to the listener. The results demonstrated that regardless of age, children performed better when EHFs were present. In addition, a small change in masker head orientation also impacted performance, with better recognition at 60° compared to 45°. These findings suggest that EHF energy in the speech signal above 8 kHz is beneficial for children in complex listening situations. The magnitude of benefit from EHF cues and talker head orientation cues did not differ between children and adults. Therefore, while EHFs were beneficial for children as young as 5 years of age, children's generally better EHF hearing relative to adults did not provide any additional benefit.