Low-rate frequency modulation detection across the lifespan

Abstract

Frequency modulation (FM) detection at a 2-Hz rate is thought to rely on temporal cues. For a 500-Hz carrier, this reliance is heightened by the use of dichotic presentation. Here, the modulator is inverted across ears such that binaural beats can cue FM. Detection acuity for FM is better in the dichotic than diotic condition, promoting the task as a measure of temporal fine structure (TFS) sensitivity. Older adults show less benefit of dichotic presentation than young adults, suggesting deficient TFS processing. This study extended the work to school-age children in order to gain a perspective of TFS processing across the lifespan. Children aged 4–10 yrs showed poorer FM detection in both diotic and dichotic conditions re young adults, and their performance was more similar to that of older adults. The dependence of the task on TFS processing was further tested by adding background noise. This reduced FM detection acuity but more for the dichotic than diotic condition. Overall, these results support the dependence of the FM detection task on TFS processing and demonstrate that such processing appears compromised at both ends of the age spectrum. [Work supported by NIDCD DC01507 (JHG) and DC00397 [EB].)Frequency modulation (FM) detection at a 2-Hz rate is thought to rely on temporal cues. For a 500-Hz carrier, this reliance is heightened by the use of dichotic presentation. Here, the modulator is inverted across ears such that binaural beats can cue FM. Detection acuity for FM is better in the dichotic than diotic condition, promoting the task as a measure of temporal fine structure (TFS) sensitivity. Older adults show less benefit of dichotic presentation than young adults, suggesting deficient TFS processing. This study extended the work to school-age children in order to gain a perspective of TFS processing across the lifespan. Children aged 4–10 yrs showed poorer FM detection in both diotic and dichotic conditions re young adults, and their performance was more similar to that of older adults. The dependence of the task on TFS processing was further tested by adding background noise. This reduced FM detection acuity but more for the dichotic than diotic condition. Overall, these results support the ...