Absence of Rhythm Benefit on Speech in Noise Recognition in Children Diagnosed With Auditory Processing Disorder

Abstract

Auditory processing disorder (APD) is a specific deficit in the processing of auditory information along the central auditory nervous system. It is characterized mainly by deficits in speech in noise recognition. APD children may also present with deficits in processing of auditory rhythm. Rhythmic neural entrainment is commonly present in perception of both speech and music, while auditory rhythmic priming of speech in noise has been known to enhance recognition in typical children. Here, we test the hypothesis that the effect of rhythmic priming is compromised in APD children, and further assessed for correlations with verbal and non-verbal auditory processing and cognition. Forty APD children and 33 neurotypical ones were assessed through (a) WRRC, a test measuring the effects of rhythmic priming on speech in noise recognition, (b) a battery of auditory processing tests, commonly used in APD diagnosis, and (c) two cognitive tests, assessing working memory and auditory attention respectively. Findings revealed that (a) the effect of rhythmic priming on speech in noise recognition is absent in APD children, (b) it is linked to non-verbal auditory processing, and (c) it is only weakly dependent on cognition. We discuss these findings in light of Dynamic Attention Theory, neural entrainment and neural oscillations and suggest that these functions may be compromised in APD children. Further research is needed (a) to explore the nature of the mechanics of rhythmic priming on speech in noise perception and why the effect is absent in APD children, (b) which other mechanisms related to both rhythm and language are also affected in this population, and (c) whether music/rhythm training can restore deficits in rhythm effects.

Keywords: auditory processing disorder; cognition; dynamic attending theory; hearing; neural entrainment; rhythm.

FIGURE 1

(A–C) Visual display of WRRC condition stimuli, i.e., beat sequence and word. Noise is not displayed in the figure. (A) RH Condition. Beat sequence and word is synchronized, all intervals are equal. (B) UnSc Condition. Word is not synchronized with beat sequence by shortening IPIs by 10%. Not all interval are equal. (C) NR Condition. Beat sequence is not isochronous by shortening and lengthening IPIs by 30%, hence no rhythm is present. RH, rhythm; UnSc, unsynchronized; NR, non-rhythm.

FIGURE 2

Means and 95% error bars for SREP (dark rectangles) and UREP (bright rectangles) scores for APD and control group respectively. SREP score units are percentages, describing the synchronized rhythm effect on speech in noise recognition. UREP score units are percentages, describing the un-synchronized rhythm effect on speech in noise recognition. Squares represent means. Error bars represent 95% confidence intervals. Dash line (y = 0) represents ‘no effect,’ i.e., recognition not affected by rhythm (see WRRC scoring). SREP, synchronized rhythm effect percentage; UREP, un-synchronized rhythm effect percentage.

FIGURE 3

(A) Scatterplot of SREP vs. UREP scores for APD group. Correlation is r = 0.492, thus the two measures share ∼24% of their total of variance. (B) Scatterplot of SREP vs. UREP scores for control group. Correlation is r = 0.754, thus the two measures share ∼57% of their total of variance. SREP, synchronized rhythm effect percentage; UREP, un-synchronized rhythm effect percentage.

FIGURE 4

(A–D) Scatterplots of SREP scores vs. SAA, RGDT, PPS, and DPS respectively, for the APD group. Correlations are r = 0.464, p = 0.026, r = –0.417, p = 0.020, r = 0.810, p < 0.001 and r = 0.591, p = 0.026. SREP, synchronized rhythm effect percentage; SAA, sustained auditory attention; PPS, pitch pattern sequence; DPS, duration pattern sequence.

FIGURE 5

(A–C) Scatterplots of UREP scores vs. RGDT, DD, and DPS respectively, for APD group. Correlations are r = –0.559, p = 0.001, r = 0.427, and r = 0.886 respectively. UREP, un-synchronized rhythm effect percentage; DD, dichotic digits; DPS, duration pattern sequence.