Effects of Age and Type of Stimulus on the Cortical Auditory Evoked Potential in Healthy Malaysian Children

Background and Objectives@#The cortical auditory evoked potential (CAEP) is a useful objective test for diagnosing hearing loss and auditory disorders. Prior to its clinical applications in the pediatric population, the possible influences of fundamental variables on the CAEP should be studied. The aim of the present study was to determine the effects of age and type of stimulus on the CAEP waveforms. @*Subjects and Methods@#Thirty-five healthy Malaysian children aged 4 to 12 years participated in this repeated-measures study. The CAEP waveforms were recorded from each child using a 1 kHz tone burst and the speech syllable /ba/. Latencies and amplitudes of P1, N1, and P2 peaks were analyzed accordingly. @*Results@#Significant negative correlations were found between age and speech-evoked CAEP latency for each peak (p0.05). The speech syllable /ba/ produced a higher mean P1 amplitude than the 1 kHz tone burst (p=0.001). @*Conclusions@#The CAEP latencies recorded with the speech syllable became shorter with age. While both tone-burst and speech stimuli were appropriate for recording the CAEP, significantly bigger amplitudes were found in speech-evoked CAEP. The preliminary normative CAEP data provided in the present study may be beneficial for clinical and research applications in Malaysian children.

Brain Activation Display Functional Asymmetry in Response to Action, Background and Tonal Frequency During a Pitch Memory Processing: An fMRI Study / Jurnal Sains Kesihatan Malaysia

@#In this study, the asymmetry of the main effects of action, background and tonal frequency during a pitch memory processingwere investigated by means of brain activation. Eighteen participants (mean age 27.6 years) were presented with low andhigh frequency tones in quiet and in noise. They listen, discriminate and recognize the target tone against the final tonein a series of four distracting tones. The main effects were studied using the analysis of variance (ANOVA) with action (towring (rubber bulb) vs. not to wring), background (in quiet vs. in noise) and frequency (low vs. high) as the factors (andlevels respectively). The main effect of action is in the right pre-central gyrus (PCG), in conformation with its contralateralbehavior. The main effect of background indicated the bilateral primary auditory cortices (PAC) and is right lateralized,attributable to white noise. The main effect of frequency is also observed in PAC but bilaterally equal and attributable tolow frequency tones. Despite the argument that the temporo-spectral lateralization dichotomy is not especially rigid asrevealed by the main effect of frequency, right lateralization of PAC for the respective main effect of background clearlydemonstrates its functional asymmetry suggesting different perceptual functionality of the right and left PAC.

Auditory Performance of Paediatric Cochlear Implant Users under the National Cochlear Implant Programme / Jurnal Sains Kesihatan Malaysia

Cochlear implant (CI) is the main intervention option for people with severe and profound sensorineural hearing loss. The purpose of this study was to investigate the auditory performance of a group of prelingually deafened paediatric cochlear implant users using direct speech perception measures (objective) and a parental questionnaire (subjective) and to identify significant demographic factors that might contribute to their performance. A total of 48 children from the Cochlear Implant Program under the Malaysian Ministry of Health with hearing age of 12 to 89 months (mean = 42.60 ± 19.46 months) participated in this study. The speech perception test was conducted using selected tests from the Malay version of the Evaluation of Auditory Response to Speech (EARS) while parental views of the children’s performance were collected using the Malay version of the Parents’ Evaluation of Aural/Oral Performance of Children (PEACH) questionnaire. The recorded speech stimuli were presented to the children in a free field at approximately 65 dB SPL in a sound treated room. The speech perception test results were then categorized using the Malay version of the Categories of Auditory Performance Index (My-CAPI) with 10 categories ranging from ‘0’ to ‘9’. Results showed that most of the children (N = 20, 41.7%) were performing at category 2 of My-CAPI (limited closed set speech perception) with three children achieved the maximum category 9 (advanced open-set sentences in noise). Communication mode was the only demographic factor that significantly correlated with the My-CAPI and PEACH scores (p < 0.01). Pearson correlation coefficient showed a strong relationship between the PEACH scores and My-CAPI levels (p < 0.01; r = 0.71) suggesting that the PEACH questionnaire can be used as an indicator of the auditory performance if the speech perception tests cannot be performed. The findings suggest that the majority of the CI children tested in this study had not achieved satisfactory auditory performance and that the use of oral communication mode was the main factor associated with better auditory outcomes. Keywords: Speech perception; children; cochlear implant; Parents’ Evaluation of Aural/Oral Performance of Children (PEACH); Categories of Auditory Performance Index (CAPI)

Superior Temporal Gyrus (STG) and Cerebellum Show Different Activation Profile during Simple Arithmetic Addition Task in Quiet and in Noisy Environment: An fMRI Study / Jurnal Sains Kesihatan Malaysia

Despite a vast number of studies that were focused on the roles of superior temporal gyrus (STG) and cerebellum as sensory area, little is known about their involvement in cognitive function such as attention and perception. The present fMRI study aimed to identify this cognitive role from brain activation profile of STG and cerebellum obtained from an arithmetic addition task. Eighteen healthy right hand dominance male adults participated in this study. They were instructed to solve single-digit addition tasks in quiet and noisy background during the fMRI scan. Both the in-quiet and in-noise addition tasks activated the bilateral STG and cerebellum (lobule VI and lobule VII) significantly but differentially. In both quiet and noisy conditions, STG activation is dominant in the left hemisphere while cerebellum showed a right hemisphere dominance. Bilateral STG and cerebellum (lobule VI) activation decreasedin noise, conversely cerebellum (lobule VII) activation increased in noise. These asymmetrical activation indicated hemispheric lateralization and differential behaviors of both brain areas in different environment while performing simple arithmetic addition task.

Effects of Ageing and Hearing Thresholds on Speech Perception in Quiet and in Noise Perceived in Different Locations

BACKGROUND AND OBJECTIVES: This study investigated the effect of ageing on speech perception in quiet and in noise, with noise directed from front, right and left. SUBJECTS AND METHODS: Sixty Malay native adults with normal or near normal hearing comprising of 20 young adults (21 to 39 years old), 20 middle aged (40 to 59 years old) and 20 older adults (60 to 74 years old) participated in this study. Their speech perception ability was measured using the Malay Hearing in Noise Test (HINT) in four test conditions; 1) in quiet (HINT Q), 2) with noise from front (HINT NF), 3) with noise from right (HINT NR), and 4) with noise from left (HINT NL). Reception thresholds for sentences (RTSs) were measured in each of the aforementioned conditions using an adaptive method. RESULTS: The results showed that, 1) genuine age-related decline was found in speech perception performance in HINT (NF), 2) hearing threshold was a major determinant differentiating speech perception performance for HINT (Q) and HINT (NL) conditions, and 3) speech perception performance for HINT (NR) was determined by both age and hearing threshold. CONCLUSIONS: This study suggests that, in older adults, while hearing thresholds affect speech perception in quiet, other factors such as central auditory processing and cognitive functions might be more important determinant factors for speech perception performance in noise.

Brain Activation during Addition and Subtraction Tasks In-Noise and In-Quiet

Background: In spite of extensive research conducted to study how human brain works, little is known about a special function of the brain that stores and manipulates information—the working memory—and how noise influences this special ability. In this study, Functional magnetic resonance imaging (fMRI) was used to investigate brain responses to arithmetic problems solved in noisy and quiet backgrounds. Methods: Eighteen healthy young males performed simple arithmetic operations of addition and subtraction with in-quiet and in-noise backgrounds. The MATLAB-based Statistical Parametric Mapping (SPM8) was implemented on the fMRI datasets to generate and analyse the activated brain regions. Results: Group results showed that addition and subtraction operations evoked extended activation in the left inferior parietal lobe, left precentral gyrus, left superior parietal lobe, left supramarginal gyrus, and left middle temporal gyrus. This supported the hypothesis that the human brain relatively activates its left hemisphere more compared with the right hemisphere when solving arithmetic problems. The insula, middle cingulate cortex, and middle frontal gyrus, however, showed more extended right hemispheric activation, potentially due to the involvement of attention, executive processes, and working memory. For addition operations, there was extensive left hemispheric activation in the superior temporal gyrus, inferior frontal gyrus, and thalamus. In contrast, subtraction tasks evoked a greater activation of similar brain structures in the right hemisphere. For both addition and subtraction operations, the total number of activated voxels was higher for in-noise than in-quiet conditions. Conclusion: These findings suggest that when arithmetic operations were delivered auditorily, the auditory, attention, and working memory functions were required to accomplish the executive processing of the mathematical calculation. The respective brain activation patterns appear to be modulated by the noisy background condition.

Mandarin Speech Perception Tests for Malaysian Chinese Children / Jurnal Sains Kesihatan Malaysia

The study aimed to develop Mandarin speech perception tests for Malaysian Chinese children. Two tests were developed which were the Syllabic Pattern Perception Test (SPPT) and the Tone Perception Test (TPT). Both tests were designed for children aged between three to six years-old. A total of 80 normal hearing children aged 3 years to 6 years and 11 months from several kindergartens around Kuala Lumpur and Ipoh participated in this study. Results showed that the mean scores for the SPPT did not differ significantly across age (p > 0.05), possibly due to a ceiling effect. Although the SPPT showed relatively low test-retest and inter-rater Spearman correlation coefficients (r = 0.68 for correct syllable pattern response and r = 0.38 for correct item response), the scores were highly repeatable in both test-retest and interrater conditions. For the TPT, the mean scores of five and six year old children were significantly higher than three year old subjects while the mean score of four year old subjects was significantly poorer than the six years old. The test-retest and inter-rater reliability were high and the coefficients approximated 0.80 (p < 0.05). For both tests, gender and dialects or languages used as the second language did not have significant effect on the test scores. Content validity evidence was also collected from a group of panelists. In conclusion, SPPT and TPT are reliable and valid Mandarin speech tests to be used on Malaysian Chinese children who speak Mandarin.