International Journal of Statistics in Medical Research, 2022, 11, 169-174 169 E-ISSN: 1929-6029/22 Are the Normative Values of Sensorineural Acuity Level (SAL) Test Affected by Head Circumferences of Subjects? Mahamad Almyzan Awang 1 , Muhammad Afiq Asyraf Suhaimi 1 , Rosdan Salim 2 , Nik Adilah Nik Othman 2 , Mohd Dasuki Sul’ain 3 , Mohd Fadzil Nor Rashid 1 and Mohd Normani Zakaria 1 1 Audiology Programme, School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia 2 Department of Otorhinolaryngology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia 3 Biomedical Science Programme, School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia Abstract: Introduction: Sensorineural acuity level (SAL) test is believed to be helpful in estimating bone conduction thresholds in masking dilemma cases. However, before the SAL normative data can be used in clinical settings, there is a need to study the fundamental variable related to SAL normative data such as head circumference. As such, the purpose of the current study was to compare SAL normative values between subjects with bigger and smaller head circumferences at different frequencies. Materials and Methods: In this study, 48 healthy Malaysian adult subjects (aged between 18 and 50 years) were enrolled. Pure tone audiometry (PTA) and SAL test were subsequently conducted based on the recommended protocols. The SAL normative values were then compared between subjects with bigger and smaller head circumferences. Data analysis methods included paired t-test, effect size, and Bayesian approach. Results: No significant differences were noted in the SAL results when the two groups were compared, implying that the SAL normative data were not influenced by the head circumference (p > 0.05, BF10 = 0.232-0.708). Conclusions: Based on the findings of this study it appears that the SAL test results are not affected by the head sizes of the subjects. Future SAL test studies may use the normative SAL values established in the current study as a guide. Keywords: Pure tone audiometry, Masking dilemma, Sensorineural acuity level test, Bone conduction, Head circumference, Bayesian statistic, Normative data. 1. INTRODUCTION Having a healthy hearing mechanism makes it possible to hear conversations and converse successfully. The incoming sounds are amplified and encoded accordingly by the outer, middle and inner ears, as well as the respective central auditory nervous system [1]. If any of the hearing organs are compromised, hearing impairment and associated symptoms may occur [2-5]. Among those who suffer from hearing loss, the type of hearing can be either conductive hearing loss (CHL), sensorineural hearing loss (SNHL) or mixed hearing loss (MHL), depending on which part of the ear is affected [1]. An accurate hearing impairment diagnosis is undoubtedly important so that the appropriate and timely management can be provided [1-3]. *Address correspondence to this author at the Audiology Programme, School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia; Tel: +609-7677691; Fax: +609-7677515; E-mail: mdnorman@usm.my In clinical settings, subjective and objective audiological tests are performed to gather complete information on the hearing diagnosis [3-10]. Among others, pure tone audiometry (PTA) has been acknowledged as the standard clinical assessment for this purpose [2, 3]. Plotted on an audiogram, bone conduction (BC) and air conduction (AC) thresholds are useful for determining the type and severity of hearing loss for each ear, respectively [1-3]. It is worth noting that for determining the AC thresholds, headphones or insert earphones are used. Whereas in the BC testing, a bone transducer vibrator is utilized to measure the BC thresholds. CHL is indicated when the BC thresholds fall within the normal limit (less than 20 dB HL) and significant air-bone gaps (ABGs) are noted on the audiogram [1]. On the other hand, abnormal AC and BC thresholds (with no ABGs) would suggest the presence of SNHL [1]. It is important to note that PTA results can be invalid if cross-hearing phenomenon occurs during the testing. As such, the masking procedure is typically conducted to address the cross-hearing issue. In particular, while