![]() ![]() Moreover, compared with masking by more predictable stimuli, the effects are often orders of magnitude greater. Thus, it occurs even when signal and masker are both clearly audible ( Brungart, 2001), and-unlike simple, energetic masking ( Fletcher, 1940)-children’s difficulties persist even when the background noise is separated from the target in time ( Hall, Buss, & Grose, 2005 Leibold & Neff, 2007), space ( Hall et al., 2005 Wightman et al., 2003), or spectral content ( Oh et al., 2001). The masking caused by an unpredictable stimulus is particularly interesting for cognitive scientists because it cannot be explained purely by peripheral auditory mechanisms (see Kidd, Mason, Richards, Gallun, & Durlach, 2007 Leibold, 2012, for reviews). ![]() This puts children at risk of missing crucial information. For example, in the presence of a noise that varies randomly between every presentation, 4- to 5-year-old children require a fivefold increase in signal intensity relative to adults ( Oh et al., 2001). However, when the background noise is chaotic and unpredictable, children’s hearing declines markedly. When the background noise is repetitive and predictable, children are often as good as adults at detecting an auditory signal ( Oh, Wightman, & Lutfi, 2001 Wightman, Callahan, Lutfi, Kistler, & Oh, 2003). Whether a teacher’s voice or an oncoming car, the ability to detect an auditory signal in a noisy environment is vital for everyday life. This work offers novel evidence that improvements in selective attention are critical for the normal development of auditory judgments. Consistent with this, age-related differences in masking were abolished when the noise was made more distant in frequency to the target. This change was explained by improvements in selective attention alone, with older listeners better able to ignore noise similar in frequency to the target. Levels of masking were found to decrease with age, becoming adult-like by 9–11 years. Psychometric fits were also used to estimate levels of internal noise and bias. Selective attention was evaluated by measuring the degree to which listeners were influenced by (i.e., gave weight to) each spectral region of the stimulus. To explore why, 187 school-age children (4–11 years) and 15 adults performed a tone-in-noise detection task, in which the masking noise varied randomly between every presentation. Children’s hearing deteriorates markedly in the presence of unpredictable noise.
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