Auditory Processing Deficits

Auditory processing deficits have frequently been proposed as a cause of reading disabilities (Farmer & Klein, 1995; Tallal, 1980). According to these accounts, deficits in auditory perception, especially problems perceiving rapidly occurring or changing sounds, leads to poor phonological representations and, in turn, difficulties in phonological awareness and reading. Early support for this view was provided by Tallal (1980). She found that poor readers had deficits in perceptual judgments of rapidly presented non-speech stimuli and that their performance was closely related to phonological decoding skills. These findings and others have led to assessment protocols (Jerger & Musiek, 2000) and intervention programs (e.g., Tallal, 2000) to address auditory processing problems in poor readers.

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).