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.

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.

Accuracy and Reliability of Smartphone Self-Test Audiometry in Community Clinics in Low Income Settings: A Comparative Study.

BACKGROUND: There is a lack of hearing health care globally, and tele-audiology and mobile technologies have been proposed as important strategies to reduce the shortfall. OBJECTIVES: To investigate the accuracy and reliability of smartphone self-test audiometry in adults, in community clinics in low-income settings. METHODS: A prospective, intra-individual, repeated measurements design was used. Sixty-three adult participants (mean age 52 years, range 20-88 years) were recruited from ENT and primary health care clinics in a low-income community in Tshwane, South Africa. Air conduction hearing thresholds for octave frequencies 0.5 to 8 kHz collected with the smartphone self-test in non-sound treated environments were compared to those obtained by reference audiometry. RESULTS: The overall mean difference between threshold seeking methods (ie, smartphone thresholds subtracted from reference) was -2.2 dB HL (n = 467 thresholds, P = 0.00). Agreement was within 10 dB HL for 80.1% (n = 467 thresholds) of all threshold comparisons. Sensitivity for detection hearing loss >40 dB HL in one ear was 90.6% (n = 84 ears), and specificity 94.2% (n = 84 ears). CONCLUSION: Smartphone self-test audiometry can provide accurate and reliable air conduction hearing thresholds for adults in community clinics in low-income settings.

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.

EHDI Africa: advocating for infants with hearing loss in Africa.

Children with hearing loss who happen to reside in Africa deserve the chance to develop according to their potential as much as their peers living in more affluent regions. This leaves a moral obligation to pursue ways of initiating, developing,and growing early hearing detection and intervention services in Africa. For these reasons, the first EHDI Africa international conference was held in Johannesburg, South Africa, in 2007 (13-14 August). The theme was 'Building bridges in Africa: Early childhood development for children with hearing loss'. This special issue contains several reports from the EHDI Africa conference.

Early hearing detection and intervention services in the public health sector in South Africa.

The purpose of this study was to examine the current status of newborn/infant hearing screening programs in public sector hospitals in South Africa by means of a descriptive survey. Data was gathered using a self-administered postal questionnaire, which included questions on screening resources and protocols, follow-up, diagnostic, and information management procedures as well as timing of intervention. The questionnaire was sent to 86 speech therapy and audiology departments within public sector hospitals throughout South Africa and 44 questionnaires were returned. The findings indicated that 27% (n=12) of respondents were conducting some form of hearing screening. The most frequently reported reasons for the absence of a screening program were a lack of appropriate equipment and a shortage of staff. Institutions with active screening programs face many challenges and programs are mostly unsystematic. Reported findings make a valuable contribution to the field of early hearing detection and intervention by providing a baseline for the development and structuring of early hearing detection and intervention services as a priority in the public healthcare sector of South Africa.

Maternal views on infant hearing loss and early intervention in a South African community.

Parental knowledge and attitudes regarding infant hearing loss are crucial to the successful implementation of EHDI programs, especially in developing countries where concerns have been raised of cultural-based ignorance and resistance towards childhood disabilities. This study investigated maternal knowledge and attitudes amongst 100 South African mothers accessing the public healthcare system using a face-to-face survey. The questionnaire (16 items) probed knowledge of infant hearing loss, superstitious cultural beliefs, and attitude towards early detection and intervention for hearing loss. Results indicate that more than 50% of the sample correctly identified three common etiological factors (ear discharge, medication, congenital) for infant hearing loss. At least one superstitious cultural belief regarding a possible cause of hearing loss was held by 57%. Maternal attitude was overwhelmingly positive with 99% indicating the desire to have their baby's hearing screened after birth and a high acceptance of hearing aids. The study demonstrates a need for increased maternal awareness regarding infant hearing loss but also a readiness for implementation of EHDI programs.

Newborn hearing screening at a community-based obstetric unit: Screening and diagnostic outcomes.

OBJECTIVE: Postnatal visits at community-based midwife obstetric units (MOUs) have been proposed as an alternative primary healthcare screening platform in South Africa. This study evaluated the outcomes of distortion product otoacoustic emissions (DPOAEs) and automated auditory brainstem response (AABR) screening conducted by a dedicated non-professional screener at a community-based MOU in the Western Cape, South Africa. METHODS: Universal newborn hearing screening (UNHS) at a community-based MOU was evaluated over a 16-month period. A dedicated non-professional screener was trained to follow a two-stage screening protocol targeting bilateral hearing loss. A two group comparative design was used alternating AABR (Maico MB11 BERAphone™()) and DPOAE (Bio-logic AuDX I) technology on a daily basis. Infants referring the initial screen received a follow-up appointment in two days' time and were rescreened with the same technology used at their first screen. Those referring the second stage were booked for diagnostic assessments. RESULTS: 7452 infants were screened including 47.9% (n=3573) with DPOAE and 52.1% (n=3879) with AABR technology. Mean age at first stage screen was 6.1 days. The initial bilateral referral rate was significantly lower for AABR (4.6%) compared to DPOAE (7.0%) and dropped to 0.3% and 0.7% respectively following the second stage screenings. First rescreen and initial diagnostic follow-up rates of 90% and 92.3% were obtained for the DPOAE group and 86.6% and 90% for the AABR group. Follow-up rates showed no significant difference between technology groups. Diagnostic assessment revealed a higher prevalence rate for bilateral SNHL among the AABR group (1/1000) compared to the DPOAE group (0.3/1000). Screening technology had no significant influence on daily screening capacity (23 AABR/day; 24 DPOAE/day). CONCLUSIONS: Postnatal visits at community-based MOUs create a useful platform for hearing screening and follow-up. AABR technology with negligible disposable costs provides opportunity for AABR screening to be utilised in community-based programmes. AABR screening offers lower initial referral rates and a higher true positive rate compared to DPOAE.

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

BACKGROUND: Otitis 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. METHODS: A 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. FINDINGS: An 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. INTERPRETATION: The 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.

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.

Auditory steady-state responses for children with severe to profound hearing loss.

OBJECTIVE: To investigate the clinical usefulness of the dichotic single-frequency auditory steady-state response (ASSR) for estimation of behavioral thresholds in children with severe to profound congenital sensorineural hearing loss. DESIGN: A comparative experimental research design was selected to compare behavioral and ASSR thresholds for the sample. Behavioral pure-tone audiometry served as the criterion standard. SETTING: Hearing Clinic, Department of Communication Pathology, University of Pretoria, Pretoria, South Africa. PATIENTS: A referred sample of 10 patients (20 ears), 5 girls and 5 boys aged 10 to 15 years (mean age, 13 years 4 months), with severe to profound sensorineural hearing impairment. MAIN OUTCOME MEASURES: The difference, and correlation, between 160 pure-tone behavioral and ASSR thresholds at 0.5, 1, 2, and 4 kHz. RESULTS: Mean differences between ASSR and behavioral thresholds were 6 dB for 0.5 kHz and 4 dB for 1, 2, and 4 kHz, with standard deviations varying between 8 and 12 dB. No significant differences (P<.05) were observed between ASSR and behavioral thresholds, except at 0.5 kHz, and Pearson correlation coefficients varied between 0.58 and 0.74 across the evaluated frequencies, with best correlation at 1 kHz and worst at 0.5 kHz. CONCLUSIONS: The ASSR thresholds provided reliable estimations of behavioral thresholds for children with severe to profound hearing loss and indicated an increased sensitivity for more profound hearing loss.

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

OBJECTIVE: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Efficacy of a community-based infant hearing screening program utilizing existing clinic personnel in Western Cape, South Africa.

OBJECTIVE: Screening programs at primary health care immunization clinics have been proposed as an alternative to hospital-based programs in South Africa. The objective of this study was to evaluate the first systematic community-based infant hearing screening program in a developing South African community in the Western Cape. METHODS: A community-based universal infant hearing screening program initiated at eight primary health care clinics in the Cape Metropolitan area was evaluated over a 19-month research period. During this time 6227 infants that were candidates for screening attended their 6, 10 or 14-week immunization visit at the relevant clinic. Clinic nurses were trained as screening personnel. A two-stage distortion product otoacoustic emissions screening protocol was utilized. The target disorder was uni- or bilateral hearing loss and infants referring the first screen were scheduled for a 4-week follow-up visit at the clinic. Diagnostic audiological and medical evaluations were scheduled at referral hospitals when indicated. The study evaluated the efficacy of the program based on coverage, referral and follow-up rates and diagnostic outcomes according to guidelines specified by the Health Professions Council of South Africa 2007 Position Statement. RESULTS: Overall coverage rate across the eight clinics was 32.4% with 2018 infants (aged 0-14 weeks) screened. The mean age of the sample at first stage screen was 3.9 weeks of age and 13.5 weeks of age for first hospital visit. Overall first stage screen referral rate was 9.5% with 62 subjects (3%) referred for diagnostic services at hospital level after a follow-up screen. The average follow-up rate for rescreens at clinic level was 85.1% and for initial diagnostic assessments at hospital level it was 91.8%. Prevalence rates were 4.5/1000 with significant hearing loss, including sensorineural (1.5/1000) and conductive (3/1000) losses, and 12.9/1000 for subjects with middle ear effusion. CONCLUSIONS: The community-based infant hearing screening program was valuable in attaining high follow-up return rates but reaching sufficient coverage may require dedicated screening personnel as opposed to existing nursing personnel.

Early hearing detection and intervention in South Africa.

Early hearing detection and intervention programs have become the standard of care to ensure optimal outcomes for infants with hearing loss, their families and society at large. The overwhelming majority of infants with congenital or early-onset permanent bilateral hearing loss are however born in developing countries like South Africa where services are scarce and awareness poor. Despite its comparatively well-developed economic and reasonably developed health care infrastructure in sub-Saharan Africa, limited information on infant hearing loss and the status of early hearing detection and intervention has been available for South Africa. Recently however, an increasing number of initiatives and reports have highlighted the extent of infant hearing loss and the status of identification and intervention services offered in the country. This report provides a review of the available evidence on infant hearing loss and the status of current early hearing detection and intervention services in South Africa.

Auditory steady-state responses for estimating moderate hearing loss.

The auditory steady-state response (ASSR) has gained popularity as an alternative technique for objective audiometry but its use in less severe degrees of hearing loss has been questioned. The aim of this study was to investigate the usefulness of the ASSR in estimating moderate degrees of hearing loss. Seven subjects (12 ears) with moderate sensorineural hearing loss between 15 and 18 years of age were enrolled in the study. Forty-eight behavioural and ASSR thresholds were obtained across the frequencies of 0.5, 1, 2, and 4 kHz. ASSR thresholds were determined using a dichotic multiple frequency recording technique. Mean threshold differences varied between 2 and 8 dB (+/-7-10 dB SD) across frequencies. The highest difference and variability was recorded at 0.5 kHz. The frequencies 1-4 kHz also revealed significantly better correlations (0.74-0.88) compared to 0.5 kHz (0.31). Comparing correlation coefficients for behavioural thresholds less than 60 and 60 dB and higher revealed a significant difference. Eighty-six percent of ASSR thresholds corresponded within 5 dB of moderate to severe behavioural thresholds compared to only 29% for mild to moderate thresholds in this study. The results confirm that the ASSR can reliably estimate behavioural thresholds of 60 dB and higher, but due to increased variability, caution is recommended when estimating behavioural thresholds of less than 60 dB, especially at 0.5 kHz.

Estimations of auditory sensitivity for young cochlear implant candidates using the ASSR: preliminary results.

This paper presents preliminary results obtained with the use of the auditory steady-state response (ASSR) technique as part of a cochlear implant candidacy assessment protocol for infants Fifteen infants (30 ears), between 10 and 60 months of age, with severe-to-profound hearing loss participated in the study. ASSR measurements were performed for 0.5, 1, 2 and 4kHz at intensities up to 120-128dB HL. The ASSR thresholds were obtained in 74%, of the measurements, and exceeded the maximum auditory brainstem response (ABR) intensity output in 91% of cases and the maximum free-field behavioral intensity output in 84% of cases. Eighty-seven per cent of ASSR threshold measurements were measured at intensities of 100dB HL or higher, and almost half (47%) were measured at intensities of 115 dB HL and higher. Preliminary results indicate that absent ABR and behavioral thresholds do not preclude the possibility of residual hearing, making the ASSR a primary source of information regarding profound levels of hearing loss.