3aPPb1 – Spectral Processing Deficits Appear to Underlie Developmental Language Disorders

Susan Nittrouer, snittrouer@phhp.ufl.edu
Joanna H. Lowenstein
Kayla Tellez
Priscilla O’Hara
Donal G. Sinex

Popular version of 3aPPb1 Spectral processing deficits appear to underlie developmental language disorders
Presented Wednesday morning, May 25, 2022
182^nd ASA Meeting
Click here to read the abstract

The Problem
Sophisticated oral and written language skills are essential to academic and occupational success in our modern, technically based society. Unfortunately, as many as twenty percent of children encounter difficulties learning language, a condition termed Developmental Language Disorder (DLD). This work was undertaken to try to uncover the root of these problems.

Brief Background
For 50 years, scientists have hypothesized that auditory problems are at the root of the challenges encountered by children with DLD. The idea is that children with DLD simply cannot recognize the acoustic structure in speech signals that underlies linguistic forms. Work in this area, however, has been fraught with controversy, and at present, no agreed-upon explanation exists.

What we did
We believe that children with DLD likely have problems processing the acoustic speech signal. In our work we changed three components of our approach from earlier work.

1. Auditory problems are likely worst at young ages and disrupt language learning at the initial stages. The auditory problems may eventually resolve, but children may be left with language deficits. We looked across ages 7-10 years for evidence of auditory problems that might be more severe in younger than older
2. The critical auditory problems may involve spectral (frequency), rather than temporal structure, as commonly manipulated. The spectral structure of speech signals is most responsible for defining linguistic We tested children on their ability to detect both temporal and spectral structure. Watch video here.
3. Word-internal elements, known as phonological units (or simply phonemes), may be disproportionately affected by auditory problems, rather than vocabulary or syntactic We tested all three kinds of skills: vocabulary, syntax, and phonology, with a focus on phonological skills. We expected to find the strongest effects of auditory problems on those phonological skills.

What we found

1. Younger children with DLD showed more severe auditory problems than older children with
2. Problems detecting spectral structure were more severe for children with DLD and lasted longer across age than problems detecting temporal
3. Problems with spectral structure were most strongly related to children’s awareness of phonological units, rather than lexical or syntactic

Significance
These findings should serve to refocus research efforts on different kinds of acoustic structure than those examined previously, as well as on specific language deficits. DLD puts children at serious risk for problems in school that can masquerade as other disorders, such as attention deficit or reading problems. Underlying conditions – including premature birth and frequent ear infections in infancy – can cause the kinds of auditory problems identified in the work reported here, and unfortunately, children living in poverty face healthcare inequities that put them at risk for those medical problems. This work is one more step in efforts to achieve equity in educational outcomes.