Sources of auditory masking in infants: Distraction effects

Abstract

Previous work has demonstrated that infants' thresholds for a pure tone are elevated by a masker more than would be predicted from their critical bandwidths. The present studies explored the nature of this additional masking. In Experiment 1, detection thresholds of6-month-old infants and of adults for a 1-kHz tone were estimated under three conditions: in quiet, in the presence of a 4-to 10-kHz bandpass noise at 40 dB SPL, and in the presence of the same noise at 50 dB SPL. The noise was gated on at the beginning of each trial. Adult thresholds were the same in all three conditions, indicating that little or no sensory masking took place in the presence of the noise. Infant thresholds were about 10 dB higher in the presence of the noise. We term this effect distraction masking. In Experiment 2, the effect of gating the noise on at trial onset was examined. Thresholds for the same tone were estimated in quiet and in the presence of the bandpass noise at 40 dB SPL, but the noise was presented continuously during the session. Under these conditions, distraction masking was still observed for infants. These findings suggest that a masker can have nonsensory effects on infants' performance in a psychoacoustic task. 405Masking has proved to be a powerful psychophysical paradigm for investigating the basic properties of sensory systems, and in recent years several investigations into the development of auditory masking have been published. Masked thresholds are often reported to be elevated in infants and children relative to adults (e.g., Allen, Wightman, Kistler, & Dolan, 1989;Nozza & Wilson, 1984;Schneider, Trehub, Morrongiello, & Thorpe, 1989), but this is not always the case, at least in older children (Veloso, Hall, & Grose, 1990). Even when the masked threshold is elevated, the amount of masking (i.e., the difference between masked and unmasked thresholds) is not always greater in younger subjects (Nozza & Wilson, 1984;Schneider et al., 1989). Olsho (1985), however, reported a case of tone-on-tone masking in 6-month-old infants where the amount of masking exhibited by the infants was about 14 dB greater than that exhibited by adults under the same condition. The purpose of the Olsho study was to estimate psychophysical tuning-eurve widths of infants and adults. The level of a .5-, 1-,2-, or 4-kHz tone, the probe, was set at 25 dB sensation level (SL). Thresholds for the probe in the presence of a second masking tone were obtained for three different masker frequencies to measure tuning- curve width, or QIO. Masker level was manipulated to define the threshold. At every masker frequency and every probe frequency, the infants exhibited masking at a masker level ranging from 11 to 16 dB lower than the level at which the adults exhibited masking. On the average, then, infants showed 14 dB more masking than did the adults. We refer to this additional masking shown by infants, relative to adults, as excess masking.Under traditional interpretation, the masked threshold is a measure of the frequency selectivity of the ...

Infant Auditory Temporal Acuity: Gap Detection

“…This suggests a general inefficiency in inFant processing oF auditory inFormation. More specifically, Werner and Bargones (1991) showed that 6-month-olds had difficulty detecting a sound in the presence oF an irrelevant sound, even when the irrelevant sound was at a distant Frequency, while adult perFormance was unaFFected by the irrelevant sound. In other words, adults listened selectively For the target, while infants did not.…”

A detection-theoretic framework for modeling informational masking

“…Some success so far has been achieved by modeling this interaction as a weighted sum of target and masker elements (Lutfi, 1993;Oh and Lutfi, 1998). However, an alternative notion is that, on some proportion of trials, the masker simply distracts attention away from the target, resulting in chance performance on those trials (Werner and Bargones, 1991). Neither idea has been widely tested, yet both make different predictions for the specific relation of d a to performance as d a varied in the conditions of Fig.…”

Issues in human auditory development

“…Thus, even though the auditory system is able to filter out much of the noise surrounding the tone, the infant has difficulty extracting the tone from the noise that remains (Bargones, Werner, & Marean, 1995;Schneider, Trehub, Morrongiello, & Thorpe, 1989;Werner & Boike, 2001). As a matter of fact, 7-9-month-old infants have difficulty extracting a tone from an irrelevant sound, even when the irrelevant sound's spectrum does not overlap with the tone's spectrum (Leibold & Werner, 2006;Werner & Bargones, 1991). While this "distraction" effect is not well understood, there are at least three possible explanations for it.…”