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.

Agreement between human voice (“Baah”) Test and Otoacoustic Emissions in Screening of infants for Binaural Hearing Loss

@#<p style="text-align: justify;"><strong>OBJECTIVE:</strong> To determine the agreement between Otoacoustic Emission and "Baah" tests for detecting binaural hearing loss in infants referred for hearing evaluation in a local community setting.<br /><strong>METHOD:</strong> This is a retrospective review done in a Private Community-based Secondary Specialty Hospital. Bilateral hearing test results of 788 neonates and infants obtained between September 2011 and January 2013 using human voice "BAAH" test and OAE were reviewed from January 2014 to September 2015.<br /><strong>RESULTS:</strong> There were 432 males and 356 females (male: female ratio 1.2:1) with a mean age of 11.17 days (range of 0-143 days). Of the 780 infants with bilateral "Pass" using OAE, all were screened as "with response" by "Baah" tests. Five infants with bilateral "refer" results using OAE yielded "no response" on "Baah" test. Sensitivity of 'Baah' test was 100%, specificity was 99.5%, with positive predictive value of 62.5%, and negative predictive value of 100%. There was good agreement noted between OAE and "Baah" (kappa=.77, p<.001).<br /><strong>CONCLUSION:</strong> The "Baah" test is a possible alternative to OAE in initially detecting binaural hearing loss in areas where equipment and personnel are limited. Although "Baah" test could only detect 62% of infants with binaural hearing loss and could not detect unilateral hearing loss, infants detected with binaural hearing loss can be immediately referred to centers with more sophisticated equipment.</p>

An experiment set-up for analysis of lateralization judgments of binaural stimuli

INTRODUCTION: The aim of this work is to present a physical implementation of a noninvasive methodology to analyze the directional sensitivity of human auditory system. A computer controlled experiment set-up has been designed and developed to study the behavior of human subjects under the presentation of interaural time delays and interaural amplitude differences for several sensation levels. METHODS: The proposed methodology comprises: the application of trains of low-pass filtered narrow pulses as acoustic binaural stimuli; the automatic, simultaneous and random variation of interaural time delays and interaural amplitude differences; the absence of human interference along the experimental sessions, except for the decision of the listener under test; the minimization of adaptation effects. RESULTS: Numerous lateralization judgments have been accomplished in order to investigate the transduction mechanism which allows deciding which side of subjects medial plane the source of binaural acoustic stimuli is located in. The behavior of decision time with the order of judgment, the sensation levels and the interaural differences in time and amplitudes has been analyzed. CONCLUSION: The noninvasive, reliable and automatic approach here presented allows obtaining psychophysical responses associated to the neuro-physiological phenomena underneath lateralization capability.