Attention Deficit Hyperactivity Disorder (ADHD) is characterized by the inability of the brain to focus and to filter irrelevant stimuli, affecting working memory and sensory gating functions. To date, medication is prescribed to control ADHD symptoms, however, the prolonged use of these medications has shown some adverse effects for individuals with ADHD. Alternatively, two non-pharmacological approaches have been proposed to help reduce ADHD symptoms, which are sound therapy interventions and systematic working memory trainings. Despite the potential use of white noise in sound therapy to reduce ADHD symptoms, it has poor melody harmonization, thus preventing children with ADHD features from participating in long training sessions. To address this issue, the present study investigated the possible use of a combination of working memory trainings and sound therapy using various sounds, including white noise, waterfall, and Quranic recitation. The present study aimed to examine the effect of sound-working memory training intervention on sensory gating, working memory, and severity of ADHD symptoms in children with ADHD features in Kuantan, Pahang. The study was conducted in three phases. In Phase 1, the Swanson, Nolan and Pelham Teachers and Parents Rating Scale of ADHD symptoms (SNAP-IV) were cross-culturally translated into Malay (M-SNAP-IV). Additionally, the Sensory Gating Scale (SGS) was also developed. The M-SNAP-IV and the new SGS were psychometrically evaluated among 702 parents and were proven to be culturally suited and valid for use in Phases 2 (participants’ selection process) and 3 (intervention). In Phase 3, 39 children aged 8 – 11 years old with ADHD symptoms participated, and these children were divided randomly into five groups [white noise + working memory training (n=8); waterfall + working memory training (n=8); Al-Fatihah + working memory training (n=8); working memory training alone (no sound stimulus) (n=8)], and one control group (n=7). The training groups received repetitive computerised working memory training for 4 – 5 weeks (10 – 13 sessions), while the control group did not receive any intervention. The Corsi test (untrained working memory test), M-SNAP-IV, and SGS were used as pre- and post-intervention testing. In general, some of the findings showed a significant increase in sensory gating abilities and working memory, and significant decrease of ADHD symptoms in the training groups. Furthermore, it was found that the combination of white noise and working memory training was the best method in improving working memory performance and sensory gating ability, and in reducing ADHD symptoms. The present study also found a significant high-negative correlation between SGS and M-SNAP-IV scores, indicating that the increase of SGS score (the severity of sensory gating deficits reduces) led to the decrease of the M-SNAP-IV score (the reduction of severity of ADHD symptoms). However, some of the findings were negative for SGS and M-SNAP-IV, for example, a significant improvement of M-SNAP-IV’s post-intervention scores was shown in the control group, which was believed to be due to random effect. To conclude, the positive findings from the current study suggested that the sound-working memory training approach has great potential as one of the future alternative psychological and behavioural approaches for ADHD intervention.

Auditory Processing Disorder (APD) is characterized by a difficulty to perceive sound due to inability to accurately process the auditory information. Several issues have been debated about APD including; (i) the conceptualization on the origin of APD, especially on the involvement of top-down processing of cognitive function in APD, (ii) the absence of gold standard assessment for APD, and (iii) the limitations in the existing APD assessments to assess younger children. To address the above-mentioned issues, this study aimed; (i) to examine the influence of attention on auditory processing performance in children with and without APD, including those with co-existing attention deficit, and (ii) to explore the potential use of Auditory Brainstem Response (ABR) test with Stroop Task to objectively identify APD. The ABR test with Stroop task in this study integrates the role of top-down processing through sensory gating pathway that possibly related to auditory processing. This thesis was divided into three main studies. In Study 1, 94 children (8 to 11 years old) with normal hearing, intelligent quotient and working memory were recruited. These children were divided into two main groups, normal and APD group, based on their performance on five APD assessments; (i) Dichotic Digit Test, (ii) Gap-in-noise Test, (iii) Pitch Pattern Sequence Test, (iv) Masking Level Difference Test and (v) Digit Triplet Test. The children in each group were further categorized into three sub-groups based on their attention status - normal attention, suspected with Attention Deficit Disorder (ADD), and suspected with Attention Deficit Hyperactivity Disorder (ADHD), by using the Swanson, Nolan and Pelham, Fourth Edition (SNAP-IV) questionnaire. In Study 2 and 3, a counting Stroop Task with three Stroop conditions (congruent, incongruent and neutral) was used. ABRs were recorded in two general conditions - with and without cognitive task. For ABRs with cognitive task, the ABR test was conducted whilst the participant performing Stroop Task in three conditions - congruent, incongruent, and neutral. The Stroop Task was conducted to generate cognitive interference, which would then activate sensory gating process. The ABR waveforms hypothetically would be affected from the effect of neural suppression as a result of sensory gating. In Study 1, the results indicate that, patient with attention problems (suspected with ADD or ADHD) may also has problem with their auditory processing skills that include significantly poor performance in binaural integration, temporal resolution and temporal ordering skill. In Study 2, two patterns of ABR with Stroop Task results were observed. Among children without APD and no attention problem, a reduction in wave V amplitude during ABR recording with cognitive interference in comparison with those without cognitive interference (a negative downward pattern) was observed. This is consistent with neural suppression as a result of normal sensory gating abilities. For children without APD but with attention deficit (ADD or ADHD), minimal reduction in wave V amplitude was observed suggesting a decline in sensory gating abilities. On the contrary, no reduction in the ABR wave V amplitude (positive upward pattern) was observed among children with APD especially those with attention problem (ADD or ADHD) suggesting absence of neural suppression that could be due to poor sensory gating abilities. In Study 3, a significant relationship were found between sensory gating and majority of auditory processing skills including; (i) binaural integration, (ii) binaural interaction, (iii) temporal resolution, and (iv) temporal sequencing. In summary, attention deficit may influence the auditory processing abilities and the ABR conducted with Stroop task has the potential to be used as a tool to identify children with APD.