Auditory Processing Deficits

Although several other studies have provided support for non-speech perceptual deficits in poor readers (Helenius, Uutela, & Hari, 1999; Menell, McAnally, & Stein, 1996; Reed, 1989), many have failed to uncover such deficits (Chiappe, Stringer, Siegel, & Stanovich, 2002; Kronbichler, Hutzler, & Wimmer, 2002; Nittrouer, 1999). In addition, others have reported that auditory processing deficits may be limited to speech perception and/or may not necessarily be temporal in nature (Adlard & Hazan, 1998; Breier, Gray, Fletcher, Foorman, & Klaas, 2002; Waber, Weiler, Wolff, Bellinger, Marcus, Ariel, Forbes, Wypij, 2001). For example, Breier and colleagues (2002) found that good and poor readers differed significantly only in speech perception (not tone perception) and that these differences were not related to temporal factors such as interstimulus interval (see also Mody, Studdert-Kennedy, & Brady, 1997).

Numerous factors could account for the inconsistency in the above research. McArthur & Bishop (2001) suggest that a lack of reliability and/or validity of auditory processing measures might explain some of the variability in the findings. They also proposed that individual differences within the population of poor readers could lead to varying results. That is, if auditory processing deficits were limited to a small portion of poor readers, then differences in subject selection approaches and/or criteria could lead to different findings. Indeed, Ramus (2003) in a review of the research (those studies providing individual data) estimated that only 39 percent of subjects showed evidence of auditory deficits. Others have also argued that processing deficits may be present only in a subgroup of poor readers. Some have proposed that these deficits are found primarily in poor readers who also have specific language impairments (Joanisse, Manis, Keating, & Seidenberg, 2000; McArthur & Hogben, 2001) or who have accompanying attention deficit disorders (Breir, Fletcher, Foorman, Klaas, & Gray, 2003; Kronbichler et al., 2002).

Not only are there inconsistencies in the evidence for the presence and nature of auditory processing deficits in poor readers, there are serious questions as to whether or not these deficits represent a sufficient cause of reading problems. In general, research indicates that performance on measures of auditory processing are unrelated or, at best, weakly related to measures of phonological awareness and reading (Bretherton & Holmes, 2003; Chiappe et al., 2002; Share, Jorm, Maclean, & Matthews, 2002; Waber et al., 2001). For example, in a population-based study of over 500 children, Share and colleagues (2002) found no significant relationship between auditory temporal processing in kindergarten and phonological awareness and phonological decoding abilities in second grade. Furthermore, they found that a select group of poor readers with temporal processing deficits were no less proficient on later phonological or reading measures than poor readers with no history of temporal processing deficits.

Taken together, the research to date does not provide a clear picture of the role of auditory processing deficits in poor readers. Perhaps future research will clarify this issue. But for now, auditory processing deficits do not appear to be a viable cause of reading disabilities.