Long-Term Training-Induced Gains of an Auditory Skill in School-Age Children As Compared With Adults

The effect of stimulus type and testing method on talker discrimination of school-age children

Efficient talker discrimination (TD) improves speech understanding under multi-talker conditions. So far, TD of children has been assessed using various testing parameters, making it difficult to draw comparative conclusions. This study explored the effects of the stimulus type and variability on children's TD. Thirty-two children (7-10 years old) underwent eight TD assessments with fundamental frequency + formant changes using an adaptive procedure. Stimuli included consonant-vowel-consonant words or three-word sentences and were either fixed by run or by trial (changing throughout the run). Cognitive skills were also assessed. Thirty-one adults (18-35 years old) served as controls. The results showed (1) poorer TD for the fixed-by-trial than the fixed-by-run method, with both stimulus types for the adults but only with the words for the children; (2) poorer TD for the words than the sentences with the fixed-by-trial method only for the children; and (3) significant correlations between the children's age and TD. These results support a developmental trajectory in the use of perceptual anchoring for TD and in its reliance on comprehensive acoustic and linguistic information. The finding that the testing parameters may influence the top-down and bottom-up processing for TD should be considered when comparing data across studies or when planning new TD experiments.

Logarithmic Versus Linear Change in Step Size When Using an Adaptive Threshold-Seeking Procedure in a Frequency Discrimination Task: Does It Matter?

Different rules for changing step sizes (e.g., logarithmic, linear) are alternately used in adaptive threshold-seeking procedures, with no clear justification. We hypothesized that the linear rule may yield more accurate thresholds for poor performers because the step sizes are predetermined and fixed across listeners and thus can be small, in contrast to the logarithmic rule, in which step sizes are changed with respect to the listener's performance. Purpose The aim of this study was to test the effect of logarithmic and linear rules on frequency discrimination (FD) thresholds. Method Three experiments involving human subjects and Monte Carlo computer simulations were designed and conducted. In the 1st experiment, FD thresholds were estimated in 40 young adults with either 3-interval 2-alternative forced choice (3I2AFC; n = 19) or 2-interval 2AFC (n = 21) in a within-subject design. In the 2nd experiment, thresholds were estimated in 16 children (7-8 years old) in a within-subject design, using 3I2AFC. In the 3rd experiment, thresholds were estimated in 30 young adults in a between-subjects design using 3I2AFC. Results No significant differences were shown between the 2 rules, regardless of age group, method, or level of FD performance. Computer simulations supported the empirical findings, predicting similar FD thresholds for both rules in the majority of runs. However, they also yielded more accurate thresholds with the linear rule, but with a larger number of outliers, which increased as the listener's attention level decreased. Conclusion Overall, the use of a particular rule has little influence on FD thresholds. Possible outliers may be minimized by monitoring the participant's attention at the beginning of the run.