Development of binaural temporal fine structure sensitivity in children.

The highest frequency for which the temporal fine structure (TFS) of a sinewave can be compared across ears varies between listeners with an upper limit of about 1400 Hz for young normal-hearing adults (YNHA). In this study, binaural TFS sensitivity was investigated for 63 typically developing children, aged 5 years, 6 months to 9 years, 4 months using the temporal fine structure-adaptive frequency (TFS-AF) test of Füllgrabe, Harland, Sęk, and Moore [Int. J. Audiol. 56, 926-935 (2017)]. The test assesses the highest frequency at which an interaural phase difference (IPD) of ϕ° can be distinguished from an IPD of 0°. The values of ϕ were 30° and 180°. The starting frequency was 200 Hz. The thresholds for the children were significantly lower (worse) than the thresholds reported by Füllgrabe, Harland, Sęk, and Moore [Int. J. Audiol. 56, 926-935 (2017)] for YNHA. For both values of ϕ, the median age at which children performed above chance level was significantly higher (p < 0.001) than for those who performed at chance. For the subgroup of 40 children who performed above chance for ϕ = 180°, the linear regression analyses showed that the thresholds for ϕ = 180° increased (improved) significantly with increasing age (p < 0.001) with adult-like thresholds predicted to be reached at 10 years, 2 months of age. The implications for spatial release from masking are discussed.