11/19/2023 0 Comments Isham 2000 dichotic listening![]() ![]() For at least 40 years, children with these symptoms have, following further testing, been diagnosed by some audiologists as having an auditory processing disorder (APD), but that diagnosis has not gained universal acceptance ( Moore, 2018), so we will generally refer to the symptoms here by the more generic and non-diagnostic term LiD. ![]() For these children, a wide variety of symptoms are reported by caregivers ( American Academy of Audiology, 2010 Moore and Hunter, 2013) that may be summarized as difficulty responding to meaningful sounds while ignoring irrelevant sounds. In practice, a considerable number of children seen at audiology clinics who have LiD are, on further testing, found to have normal audiograms, the pure-tone detection, gold-standard measure of hearing ( Hind et al., 2011). By definition, therefore, children with LiD may have problems with thought, attention, or hearing. Listening is often considered to be the active counterpart of passive hearing “paying thoughtful attention to sound” ( Keith et al., 2019 after Merriam-Webster). Overall, the children with LiD had only subtle differences from TD children in the BDLT, and correspondingly minor changes in brain activation. Significant correlations between brain activity level and BDLT were found in several frontal and temporal locations for the TD but not for the LiD group. Neural activity associated with Speech, Phonetic, and Intelligibility sentence cues did not differ significantly between groups. Children with LiD had significantly larger mean LIs than TD children for stimuli with ILDs, especially those favoring the left ear. Laterality indices were small and tended to increase with age, as previously reported. However, a significant interaction was found between ear, group, and ILD. Neither group, age, nor report method affected the LI of right/left recall. Some activated areas were correlated with dichotic results in TD children only. fMRI measured brain activation produced by a receptive speech task that segregated speech, phonetic, and intelligibility components. Dichotic listening (DL) data were analyzed initially by group (LiD, TD), age, report method (NF, FR, FL), and ILD (0, ± 15 dB) and compared with speech-in-noise thresholds (LiSN-S) and cognitive performance (NIH Toolbox). Interaural level differences (ILDs) manipulated bottom-up perceptual salience. Children reported the syllable heard most clearly (non-forced, NF) or the syllable presented to the right or left ear. Different single syllables (ba, da, ga, pa, ta, ka) were presented simultaneously to each ear (6 × 36 trials). We examined the ability of 6–13 year old (y.o.) children with normal audiometric thresholds to identify and selectively attend to dichotically presented CV syllables using the Bergen Dichotic Listening Test (BDLT Children were recruited as typically developing (TD n = 39) or having LiD ( n = 35) based primarily on composite score of the ECLiPS caregiver report. Impaired interactions between the two ears have been proposed as an important component of LiD when there is no hearing loss, also known as auditory processing disorder (APD). The relationship of this functional and neuroanatomical model to known neural correlates of working memory is considered.Listening difficulties (LiD) are common in children with and without hearing loss. ![]() It is further suggested that left STG activity is associated with dichotic listening effects and may be influenced by working memory span capacity. It is suggested that the right STG may be involved in the ISE and a particularly strong left ear effect might occur because of the contralateral connections in audition. Positron emission tomography (PET) imaging data (Scott et al., 2004, submitted) show bilateral activation of the superior temporal gyrus (STG) in the presence of intelligible, but ignored, background speech and right hemisphere activation of the STG in the presence of unintelligible background speech. A right ear processing bias is apparent in dichotic listening, whereas the bias is to the left ear in the ISE (Hadlington et al., 2004). Dichotic listening is open to moderating effects of working memory capacity (Conway et al., 2001) whereas irrelevant sound effects (ISE) are not (Beaman, 2004). The assumption that ignoring irrelevant sound in a serial recall situation is identical to ignoring a non-target channel in dichotic listening is challenged. ![]()
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