Mohd Normani Zakaria

Gender Disparities in Speech-evoked Auditory Brainstem Response in Healthy Adults: Any Relation to Head Size?

Objectives: Gender disparities in speech-evoked auditory brainstem response (speech-ABR) outcomes have been reported, but the literature is limited. The present study was performed to further verify this issue and determine the influence of head size on speech-ABR results between genders. Methods: Twenty-nine healthy Malaysian subjects (14 males and 15 females) aged 19 to 30 years participated in this study. After measuring the head circumference, speech-ABR was recorded by using synthesized syllable /da/ from the right ear of each participant. Speech-ABR peaks amplitudes, peaks latencies, and composite onset measures were computed and analyzed. Results: Significant gender disparities were noted in the transient component but not in the sustained component of speech-ABR. Statistically higher V/A amplitudes and less steeper V/A slopes were found in females. These gender differences were partially affected after controlling for the head size. Conclusions: Head size is not the main contributing factor for gender disparities in speech-ABR outcomes. Gender-specific normative data can be useful when recording speech-ABR for clinical purposes.

The Hyperactivity of Efferent Auditory System in Patients with Schizophrenia: A Transient Evoked Otoacoustic Emissions Study

Objective Electrophysiological studies, which are mostly focused on afferent pathway, have proven that auditory processing deficits exist in patients with schizophrenia. Nevertheless, reports on the suppressive effect of efferent auditory pathway on cochlear outer hair cells among schizophrenia patients are limited. The present, case-control, study examined the contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) in patients with schizophrenia. Methods Participants were twenty-three healthy controls and sixteen schizophrenia patients with normal hearing, middle ear and cochlear outer hair cells function. Absolute non-linear and linear TEOAEs were measured in both ears by delivering clicks stimuli at 80 dB SPL and 60 dB SPL respectively. Subsequently, contralateral suppression was determined by subtracting the absolute TEOAEs response obtained at 60 dBpe SPL during the absence and presence of contralateral white noise delivered at 65 dB HL. No attention tasks were conducted during measurements. Results We found no significant difference in absolute TEOAEs responses at 80 dB SPL, in either diagnosis or ear groups (p>0.05). However, the overall contralateral suppression was significantly larger in schizophrenia patients (p<0.05). Specifically, patients with schizophrenia demonstrated significantly increased right ear contralateral suppression compared to healthy control (p<0.05). Conclusion The present findings suggest increased inhibitory effect of efferent auditory pathway especially on the right cochlear outer hair cells. Further studies to investigate increased suppressive effects are crucial to expand the current understanding of auditory hallucination mechanisms in schizophrenia patients.

Evaluation of auditory hallucinations in patients with schizophrenia: A validation study of the Malay version of Psychotic Symptom Rating Scales (PSYRATS)

The Psychotic Symptom Rating Scales (PSYRATS) is the most widely used validated scale to measure the specific symptoms of auditory hallucination and delusion. The aim of this study was to validate and to examine the psychometric properties of the auditory hallucination component of the Malay PSYRATS (MyPSYRATS). The research was done in the Universiti Kebangsaan Malaysia Medical Center (UKMMC) among 51 schizophrenia inpatients and outpatients who had experienced or reported verbal auditory hallucination. The psychometric properties of MyPSYRATS (auditory hallucination) were studied and a comparison was made between the psychometric properties obtained and the Positive and Negative Syndrome Scale (PANSS). The internal consistency of MyPSYRATS was good as revealed by Cronbachs alpha value. Factor analysis replicated three components (emotional, cognitive, and physical) similar to the factorial structure of the original auditory hallucination scale. However, two items were regrouped under the emotional component. Spearmans rank-order correlation showed a significant positive relationship between the total score of auditory hallucinations and PANSS auditory hallucinations item (P3). In conclusion, the auditory hallucination domain of MyPSYRATS is a reliable and valid assessment tool for further clinical applications.

The Dominance of Ossicular Route in Sound Transmission

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Gender differences in binaural speech-evoked auditory brainstem response: are they clinically significant?

INTRODUCTION Binaurally evoked auditory evoked potentials have good diagnostic values when testing subjects with central auditory deficits. The literature on speech-evoked auditory brainstem response evoked by binaural stimulation is in fact limited. Gender disparities in speech-evoked auditory brainstem response results have been consistently noted but the magnitude of gender difference has not been reported. OBJECTIVE The present study aimed to compare the magnitude of gender difference in speech-evoked auditory brainstem response results between monaural and binaural stimulations. METHODS A total of 34 healthy Asian adults aged 19-30 years participated in this comparative study. Eighteen of them were females (mean age=23.6±2.3 years) and the remaining sixteen were males (mean age=22.0±2.3 years). For each subject, speech-evoked auditory brainstem response was recorded with the synthesized syllable /da/ presented monaurally and binaurally. RESULTS While latencies were not affected (p>0.05), the binaural stimulation produced statistically higher speech-evoked auditory brainstem response amplitudes than the monaural stimulation (p<0.05). As revealed by large effect sizes (d>0.80), substantive gender differences were noted in most of speech-evoked auditory brainstem response peaks for both stimulation modes. CONCLUSION The magnitude of gender difference between the two stimulation modes revealed some distinct patterns. Based on these clinically significant results, gender-specific normative data are highly recommended when using speech-evoked auditory brainstem response for clinical and future applications. The preliminary normative data provided in the present study can serve as the reference for future studies on this test among Asian adults.

Listening to sentences in noise: Revealing binaural hearing challenges in patients with schizophrenia

Objective The present, case-control, study investigates binaural hearing performance in schizophrenia patients towards sentences presented in quiet and noise. Methods Participants were twenty-one healthy controls and sixteen schizophrenia patients with normal peripheral auditory functions. The binaural hearing was examined in four listening conditions by using the Malay version of hearing in noise test. The syntactically and semantically correct sentences were presented via headphones to the randomly selected subjects. In each condition, the adaptively obtained reception thresholds for speech (RTS) were used to determine RTS noise composite and spatial release from masking. Results Schizophrenia patients demonstrated significantly higher mean RTS value relative to healthy controls (p=0.018). The large effect size found in three listening conditions, i.e., in quiet (d=1.07), noise right (d=0.88) and noise composite (d=0.90) indicates statistically significant difference between the groups. However, noise front and noise left conditions show medium (d=0.61) and small (d=0.50) effect size respectively. No statistical difference between groups was noted in regards to spatial release from masking on right (p=0.305) and left (p=0.970) ear. Conclusion The present findings suggest an abnormal unilateral auditory processing in central auditory pathway in schizophrenia patients. Future studies to explore the role of binaural and spatial auditory processing were recommended.

Auditory Brainstem Response (ABR) Findings With Click and CE-Chirp Stimulations in Noise-Exposed Participants

We read with great interest the article by Pushpalatha and Konadath entitled “Auditory brainstem responses for click and CE-chirp stimuli in individuals with and without occupational noise exposure.” The effort to study the noise-exposed individuals by means of auditory brainstem response (ABR) recorded with click and CE-chirp stimulations should be commended. In general, the results obtained were in line with the findings from previous studies that investigated the effects of noise on the central auditory nervous system. The authors then concluded that the CEchirp stimulus was more effective than the click in identifying early pathological changes due to occupational noise exposures. Nevertheless, in regard to the reported study findings, we wish to highlight some issues that might be worthy of consideration.

Electrocochleographic recording in Asian adults: Preliminary normative data and demographic analyses

Objective Electrocochleography (ECochG) is valuable to diagnose Menieres disease objectively. The aim of the present study was to provide preliminary normative data for ECochG among Asian adults. The influences of ethnicity (Malay versus Chinese) and gender on ECochG results were also studied. Methods Twenty-two Malay adults (10 men and 12 women) and twenty Chinese participants (10 men and 10 women) aged between 20 and 49 years participated in this study. Extratympanic ECochG (ET-ECochG) was recorded according to standard non-invasive procedure. Summating potential (SP) amplitude, action potential (AP) amplitude and SP/AP ratio were analyzed accordingly. Results ET-ECochG results were found to be comparable between left and right ears (p > 0.05). No notable differences in ET-ECochG results were found between Malay and Chinese groups (p > 0.05). No significant influence of gender on ET-ECochG outcomes was also noted (p > 0.05). The derived normative data for Asian adults (84 ears) are consistent with previous reports. Conclusion The present study provides preliminary normative data for ET-ECochG among Asian adults. The ECochG components do not appear to be influenced by either ethnicity or gender. The derived normative data can be used for clinical applications and as the reference for future studies involving Asian population.

Estimation of noise induced hearing loss (NIHL) with hearing deterioration index (HDI)

Dear Editor, We read with great interest the article written by Balaji et al., entitled “Hearing Impairment and High Blood Pressure among Bus Drivers in Puducherry” [1]. Noise Induced Hearing Loss (NIHL) is common among vehicle drivers and research in this area is much relevant. In this interesting study, the authors had utilized Hearing Deterioration Index (HDI) as an indirect method for assessing NIHL. In the literature, not many NIHL studies have adopted this method (particularly for determining hearing impairment among noise exposed workers) and the authors should be commended for their effort. Nevertheless, we wish to highlight some issue that might be worthy of consideration. Since HDI is an indirect method for assessing NIHL, perhaps the sentence “at risk of developing NIHL” is preferable to be used. Even though HDI was formulated using large retrospective samples and logical assumptions [2], hearing impairment among noise exposed workers can only be confirmed by a known clinical hearing test, i.e., Pure Tone Audiometry (PTA). The direct measurement of hearing status is always beneficial as some individuals are more susceptible to acquire NIHL than others when exposed to similar acoustical environments. This individual susceptibility issue has been acknowledged and reported in the literature. Apart from the environmental factors (e.g. noise level,exposure duration, years of working etc.), individual susceptibility to noise damage is also contributed by biological factors including age, gender, race, eye color, degree of hearing loss, ear laterality and genetic [3,4]. Even though NIHL typically shows a symmetrical pattern in noise-exposed workers, the left ear can be more vulnerable to hearing damage than the right ear in some individuals [3]. By utilizing PTA, left and right ear information can be obtained separately in a convenient manner. More recently, a well-controlled genetic study has identified a key gene for susceptibility to NIHL [4]. This further supports the notion that some individuals are more genetically susceptible to noise damage than others. Notwithstanding, we agree with the authors that PTA is not easily accessible and an optimum testing environment (e.g., sound proof room or booth) is required for conducting PTA. In this regard, if a similar study to be expanded in future, perhaps a simpler hearing test such as Otoacoustic Emission (OAE) can be considered for screening NIHL. OAE is a rapid objective test that has been used widely for hearing screening. In fact, OAE can be reliably conducted even in less optimum testing conditions (i.e., background noise levels of up to 70dBA) [5].More studies are warranted to further explore the potential use of HDI in NIHL testing. For example, studies on determining the correlation between HDI and hearing tests (PTA and/or OAE) should be conducted to justify the usefulness of HDI as an indirect screening method for NIHL. Finally, we fully agree with the authors that awareness and preventive programmes are required for reducing the occurrence of NIHL among the drivers. In fact, the HDI values can also be considered when developing guidelines in the NIHL preventive programmes