Vuvuzela sound measurements

We recently published a scientific letter in the South African Medical Journal reporting the maximum output levels of a Vuvuzela. The publication has drawn varied reactions from the media and other interested parties. In response to enquiries the additional information on the method and results reported in the earlier paper is provided

Otitis Media Diagnosis for Developing Countries Using Tympanic Membrane Image-Analysis

AbstractBackgroundOtitis media is one of the most common childhood diseases worldwide, but because of lack of doctors and health personnel in developing countries it is often misdiagnosed or not diagnosed at all. This may lead to serious, and life-threatening complications. There is, thus a need for an automated computer based image-analyzing system that could assist in making accurate otitis media diagnoses anywhere.MethodsA method for automated diagnosis of otitis media is proposed. The method uses image-processing techniques to classify otitis media. The system is trained using high quality pre-assessed images of tympanic membranes, captured by digital video-otoscopes, and classifies undiagnosed images into five otitis media categories based on predefined signs. Several verification tests analyzed the classification capability of the method.FindingsAn accuracy of 80.6% was achieved for images taken with commercial video-otoscopes, while an accuracy of 78.7% was achieved for images captured on-site with a low cost custom-made video-otoscope.InterpretationThe high accuracy of the proposed otitis media classification system compares well with the classification accuracy of general practitioners and pediatricians (~64% to 80%) using traditional otoscopes, and therefore holds promise for the future in making automated diagnosis of otitis media in medically underserved populations

Auditory steady-state response and auditory brainstem response thresholds in children.

The inclusion of the auditory steady-state response (ASSR) into test-batteries for objective audiometry has allowed for clinical comparisons with the most widely used procedure, the auditory brainstem response (ABR). The current study describes ASSR and ABR thresholds for a group of infants and young children with various types and degrees of hearing loss. A sample of 48 subjects (23 female) with a mean age of 2.8+/-1.9 years SD were assessed with a comprehensive test-battery and classified according to type and degree of hearing loss. Thresholds were determined with a broadband click-evoked ABR and single frequency ASSR evoked with continuous tones (0.25-4 kHz) amplitude modulated (67-95 Hz). Mean difference scores (+/-SD) between the ABR and high frequency ASSR thresholds were 9.8 (+/-11), 3.6 (+/-12) and 10.5 (+/-12) dB at 1, 2 and 4 kHz, respectively. An ASSR mean threshold for 2-4 and 1-4 kHz compared to the ABR threshold revealed an average difference of 7 (+/-9) and 7.9 (+/-8) dB, respectively. The overall correlation between the ABR and ASSR thresholds was highest for the mean ASSR thresholds of 2-4 and 1-4 kHz (r=0.92 for both conditions). Correlations between the ABR and individual ASSR frequencies were slightly less (0.82-0.86). The average of the 2-4 kHz ASSR thresholds correlated best with the click-evoked ABR for all categories of hearing loss except for the sensorineural hearing loss category for which the 1-4 kHz ASSR average was better correlated to ABR thresholds. Findings demonstrate the reliability of verifying high frequency ASSR thresholds with a click-evoked ABR as an important cross-check in infants for whom behavioural audiometry may not be possible

Predicting pure-tone thresholds with dichotic multiple frequency auditory steady state responses

The accuracy of dichotic multiple frequency auditory steady state in predicting pure-tone thresholds at 0.5, 1, 2, and 4.0 kHz compared to an ABR protocol (click and tone burst at 0.5 kHz) were explored in a group of 25 hearing-impaired subjects across the degree and configuration spectrum. Mean steady state thresholds were within 14, 18, 15, and 14 dB of the pure tones at 0.5, 1, 2, and 4 kHz, compared to the tone-burst ABR at 0.5 kHz pure-tone difference of 24 dB, and a click-evoked pure-tone (2-4 kHz) difference of 9 dB. Recording time for the steady state protocol was 28 minutes (+/-11) compared to 24 minutes (+/- 9) of the ABR protocol. Degree of loss had a significant effect on steady state; configuration of hearing loss had a limited effect. Mf ASSR predicted thresholds with relative accuracy although some configurations showed discrepancies for low-frequency estimates

Establishing normal hearing with the dichotic multiple-frequency auditory steady-state response compared to an auditory brainstem response protocol

To determine the clinical usefulness of the dichotic multiple-frequency (MF) auditory steady-state response (ASSR) technique for estimating normal hearing compared to a 0.5-kHz tone burst and broadband click auditory brainstem response (ABR) protocol in a sample of adults.A comparative experimental research design was selected in order to compare estimations of normal hearing obtained with the dichotic ASSR technique at 0.5, 1, 2 and 4 kHz with a 0.5-kHz tone burst and broadband click ABR protocol. The recording times required for each procedure were also compared. Normal-hearing subjects (n = 28) were selected according to immittance values within normal limits and pure-tone behavioural thresholds of < 25 dB HL across frequencies.The dichotic MF ASSR estimated normal hearing to be, on average, 30-34 dB HL across the range 0.5-4 kHz. The mean estimate of normal hearing for 0.5 kHz using tone burst ABRs was 30 dB nHL and the mean click ABR threshold was 16 dB nHL, i.e. 14-18 dB better than the ASSR thresholds. The dichotic MFASSR technique recorded 8 thresholds (4 in each ear) in a mean time of 23 min. The ABR protocol recorded 4 thresholds (2 in each ear) in a mean time of 25 min.Both the dichotic MF ASSR and ABR protocols provided a time-efficient estimation of normal hearing. There was no significant difference between the tone burst ABR and MF ASSR techniques in terms of estimation of normal hearing at 0.5 kHz. The dichotic MF ASSR technique proved more time-efficient by determining more thresholds in a shorter time compared to the ABR protocol

International classification of functioning, disability, and health core sets for hearing loss: A discussion paper and invitation

The World Health Organization's International Classification of Functioning, Disability and Health (ICF) has adopted a multifactorial understanding of functioning and disability, merging a biomedical paradigm with a social paradigm into a wider understanding of human functioning. Altogether there are more than 1400 ICF-categories describing different aspects of human functioning and there is a need to developing short lists of ICF categories to facilitate use of the classification scheme in clinical practice. To our knowledge, there is currently no such standard measuring instrument to facilitate a common validated way of assessing the effects of hearing loss on the lives of adults. The aim of the project is the development of an internationally accepted, evidence-based, reliable, comprehensive and valid ICF Core Sets for Hearing Loss. The processes involved in this project are described in detail and the authors invite stakeholders, clinical experts and persons with hearing loss to actively participate in the development process

The development of an Afrikaans test for sentence recognition thresholds in noise

OBJECTIVE: The development of a valid and reliable Afrikaans test of sentence recognition thresholds in noise. DESIGN: A collection of sentences was developed, rated for naturalness and grammatical complexity, and digitally recorded using a female speaker. Sentences found to have similar psychometric curve slopes, with equivalent intelligibility at three different noise levels, were arranged into 22 phonemically matched lists of ten sentences each. List equivalence was evaluated in normal-hearing listeners in full and reduced bandwidth conditions. Test-retest reliability of the remaining lists was evaluated in a second group of listeners. STUDY SAMPLE: All listeners were native speakers of Afrikaans with normal hearing. For evaluation of list equivalence, ten listeners were used. Twenty other listeners were used to evaluate test-retest reliability. RESULTS: A collection of eighteen phonemically matched lists was produced. Lists were found to be of equivalent difficulty in full and reduced bandwidth conditions, and to have good test-retest reliability in normal-hearing listeners. The average recognition threshold of these lists was -2.73 dB signal-to-noise ratio (standard deviation = 0.64 dB), and within-subject variability was 1.22 dB. CONCLUSIONS: The developed test provides a valid and reliable means of measuring sentence recognition thresholds in noise in Afrikaans.This project was financially supported by the National Research Foundation of South Africa