Perception of Filtered Speech by Children with Developmental Dyslexia and Children with Specific Language Impairments.

Usha Goswami,Martina Huss,Ruth Cumming,Tim Fosker,Natasha Mead,Maria Chait,Lisa Barnes,Angela M Wilson

doi:10.3389/fpsyg.2016.00791

Abstract

Here we use two filtered speech tasks to investigate children’s processing of slow (<4 Hz) versus faster (∼33 Hz) temporal modulations in speech. We compare groups of children with either developmental dyslexia (Experiment 1) or speech and language impairments (SLIs, Experiment 2) to groups of typically-developing (TD) children age-matched to each disorder group. Ten nursery rhymes were filtered so that their modulation frequencies were either low-pass filtered (<4 Hz) or band-pass filtered (22 – 40 Hz). Recognition of the filtered nursery rhymes was tested in a picture recognition multiple choice paradigm. Children with dyslexia aged 10 years showed equivalent recognition overall to TD controls for both the low-pass and band-pass filtered stimuli, but showed significantly impaired acoustic learning during the experiment from low-pass filtered targets. Children with oral SLIs aged 9 years showed significantly poorer recognition of band pass filtered targets compared to their TD controls, and showed comparable acoustic learning effects to TD children during the experiment. The SLI samples were also divided into children with and without phonological difficulties. The children with both SLI and phonological difficulties were impaired in recognizing both kinds of filtered speech. These data are suggestive of impaired temporal sampling of the speech signal at different modulation rates by children with different kinds of developmental language disorder. Both SLI and dyslexic samples showed impaired discrimination of amplitude rise times. Implications of these findings for a temporal sampling framework for understanding developmental language disorders are discussed.

Highlights

The proposal that human speech perception relies on multi-time resolution processing is increasingly well-supported by both behavioral and neuroimaging data (Poeppel, 2003; Greenberg, 2006; Hickok and Poeppel, 2007; Luo and Poeppel, 2007; Giraud et al, 2008; Ghitza and Greenberg, 2009; Chait et al, 2015)
From the perspective of temporal sampling of the speech signal, it is logically possible that while children with both disorders share a difficulty in processing amplitude envelope (AE) rise times and the temporal modulation patterns in speech, the rates of temporal integration that are impaired may differ for each disorder
We proposed that while the AE rise time impairments that are found in children with dyslexia and speech and language impairments (SLIs) may indicate a shared sensory difficulty in processing temporal modulation patterns in speech, the neural temporal integration windows that are most impaired may differ for each disorder

Summary

Introduction

The proposal that human speech perception relies on multi-time resolution processing is increasingly well-supported by both behavioral and neuroimaging data (Poeppel, 2003; Greenberg, 2006; Hickok and Poeppel, 2007; Luo and Poeppel, 2007; Giraud et al, 2008; Ghitza and Greenberg, 2009; Chait et al, 2015). According to multi-time resolution models, the brain tracks the temporal modulation patterns in speech at different timescales simultaneously, via phase-locking of intrinsic cortical oscillations to modulations at corresponding timescales. Rise times appear to phase re-set neuronal activity, enabling accurate ‘sampling’ of the speech input in different temporal integration windows simultaneously, thereby supporting the parsing and encoding/decoding of speech (Luo and Poeppel, 2007; Poeppel, 2014)

Methods

Results

Conclusion