Audiol. Res., Volume 3, Issue 1 (December 2013) – 9 articles

The aim of the present study was to investigate the effect of stimulus polarity on speech evoked auditory brainstem response (ABR). In order to accomplish it, speech evoked ABR was recorded with various stimulus polarities from 17 normally hearing adults. The result of the study shows differential effect of stimulus polarity on components of speech evoked ABR. Latency of peaks for onset, sustained and offset responses of speech evoked ABR were found to be not significantly different across stimulus polarities. In contrast, the amplitude of first formant and high frequency components was found to be significantly reduced for alternating polarity compared to single polarity, while amplitude of fundamental frequency response was not affected by polarity of the stimuli. Thus speech evoked ABR may be recorded using single polarity rather than using alternating polarities. Full article

ClearVoice™ enables Advanced Bionics cochlear implant users to improve their speech understanding in difficult listening environments, without compromising performance in quiet situations. The aim of the study was to evaluate the benefits of ClearVoice in children. Children between six and fourteen years of age randomly tested two modalities of ClearVoice for one month each. The baseline program, HiRes 120™, and both ClearVoice programs were evaluated with a sentence test in quiet and noise. Parents and teachers completed a questionnaire related to everyday noisy situations. The switchover to ClearVoice was uneventful for both modalities. Adjustments to thresholds and comfort levels were required. Seven out of the nine children preferred a ClearVoice program. No impact of ClearVoice on performance in quiet was observed and both modalities of ClearVoice improved speech understanding in noise compared to the baseline program, significantly with ClearVoice high. Positive outcomes were obtained from the questionnaires and discussions with parents and children. This study showed that children benefited from using ClearVoice in their daily life. There was a clear trend towards improved speech understanding in noise with ClearVoice, without affecting performance in quiet; therefore ClearVoice can be used by children all day, without having to change programs. Full article

The current study aimed to determine the current practice of pediatric physicians in the referral of children (0-3 years) for further audiological evaluation in the South African public health care sector. Sixty three pediatric physicians comprising of pediatricians, neonatologists, medical officers, registrars and interns from three academic hospitals completed a self- administered questionnaire. Most participants reported referrals to an audiologist when hearing loss was suspected. An average of eight risk factors for hearing loss listed on the Health Professionals Council of South Africa (HPCSA) 2007 position statement were identified by participants, indicating the need for referral. Generally, participants reported that referral/s occurred easily within the respective hospitals. Results highlight that pediatric physicians are aware of the role that audiologists play in the diagnosis and management of hearing loss, are involved in the referral of children that are at risk for hearing loss, and have awareness of some of the known risk factors associated with hearing loss. Further education regarding other risk factors is required in order to increase referral/s, and ensure appropriate referral of children at risk for hearing loss. Full article

Items pertaining to hearing and hearing aids from the Hearing Aid Rehabilitation Questionnaire were applied to a heterogeneous sample of Dutch patients aged 55 years and more to evaluate their potential use in hearing screening. Subjects aged 55+ were recruited from a large general practitioners practice to participate. Three groups were formed: a group of 63 persons with a hearing aid, a group of 64 without a hearing aid but with sufficient hearing impairment to qualify for hearing aid reimbursement, and a group of 85 non-hearing impaired persons. Factor and reliability analyses revealed a structure with two scales regarding hearing, namely functionality and social hearing and three scales pertaining to hearing aids, namely hearing aid stigma, pressure to be assessed and not wanting a hearing aid. Scale validity was assessed with pure tone averages over the frequencies 1, 2 and 4 kHz and with a visual analogue scale for subjective hearing. The derived scales can be applied reliably in audiological assessment in an adult hearing screen setting to detect experienced hearing problems as well as attitudes related to hearing and hearing aids. Full article

The objective of the study was to assess the sacculocollic and otolith ocular pathway function using cervical vestibular evoked myogenic potentials (cVEMP) and ocular vestibular myogenic potentials (oVEMP) in dancers and non dancers. Total 16 subjects participated in the study. Out of 16 participants, 8 were trained in Indian classical form of dance (dancers) and other 8 participants who were not trained in any dance form (non dancers). cVEMP and oVEMP responses were recorded for all the subjects. Non Parametric Mann-Whitney U test revealed no significant difference between dancers and non dancers for the latency and amplitude parameter for cVEMP and oVEMP, i.e. P13, N23 latency and P13-N23 complex amplitude and N10, P14 latency, N10-P14 complex amplitude respectively. The vestibular system comprises of several structures. It is possible that the dance style practiced by the dancer’s group assessed in this study does not contribute towards improving the plasticity of the sacculocollic and otolith-ocular pathways. It can be concluded that not all forms of dance training brings about a change in the plasticity of the sacculocollic and otolithocular pathways. Full article

Open-fit hearing aids (OFHAs) may be of benefit for some individuals with chronic outer and middle ear conditions for which boneanchored hearing devices (BAHDs) are normally recommended. The purpose of this study was to compare performance between OFHAs and BAHDs. A Starkey Destiny 800 OFHA was fit on eight adult BAHD users and speech perception measures in quiet and in background noise were compared under two different test conditions: i) BAHD only and ii) OFHA only. Equivalent outcome measure performance between these two conditions suggests that the OFHA was able to provide sufficient amplification for mild to moderate degrees of hearing loss (pure-tone averages (PTAs) less than 47 dB HL). The improved speech perception performances and increased loudness ratings observed for several of the participants with moderately-severe to severe degrees of hearing loss (PTAs of 47 dB HL or greater) in the BAHD only condition suggest that the OFHA did not provide sufficient amplification for these individuals. Therefore, OFHAs may be a successful alternative to the BAHD for individuals with no more than a moderate conductive hearing loss who are unable or unwilling to undergo implant surgery or unable to wear conventional hearing aids due to allergies, irritation, or chronic infection associated with the ear being blocked with a shell or earmold. Full article

“Auditory neuropathy spectrum disorder” is a clinical disorder where the outer hair cell functioning is intact but the functioning of the auditory nerve is affected. Since, the 8th nerve is constituted by both the auditory and vestibular branch of nerve fibers, there are chances that the vestibular nerve might also be affected. Hence, the current study was carried out in order to determine the functioning of vestibular nerve in individuals with Auditory Neuropathy. A total of 11 participants were considered for the current study. cVEMPs and oVEMPs were administered using the conventional protocol. In all the participants (100%) the oVEMPs were absent whereas in 2 ears out of 22 ears tested (90.90%) the cVEMPs were absent. The results of the present study indicate a high incidence of vestibular involvement in individuals with auditory neuropathy spectrum disorders. Also, it necessitates the inclusion of vestibular tests in the test battery used to assess individuals with auditory neuropathy spectrum disorder. Full article

This study investigates changes in amplitude and delays in low-frequency toneburst cochlear microphonic (CM) waveforms recorded at the ear canal in response to different stimulus intensities. Ten volunteers aged 20-30 were recruited. Low-frequency CM waveforms at 500 Hz in response to a 14-ms toneburst were recorded from an ear canal electrode using electrocochleography techniques. The data was statistically analyzed in order to confirm whether the differences were significant in the effects of stimulus intensity on the amplitudes and delays of the low-frequency CM waveforms. Electromagnetic interference artifacts can jeopardize CM measurements but such artifacts can be avoided. The CM waveforms can be recorded at the ear canal in response to a toneburst which is longer than that used in ABR measurements. The CM waveforms thus recorded are robust, and the amplitude of CM waveforms is intensity-dependent. In contrast, the delay of CM waveforms is intensity-independent, which is different from neural responses as their delay or latency is intensity-dependent. These findings may be useful for development of the application of CM measurement as a supplementary approach to otoacoustic emission (OAE) measurement in the clinic which is severely affected by background acoustic noise. The development of the application in the assessment of low-frequency cochlear function may become possible if a further series of studies can verify the feasibility, but it is not meant to be a substitute for audiometry or OAE measurements. The measurement of detection threshold of CM waveform responses using growth function approach may become possible in the clinic. The intensity-independent nature of CMs with regards to delay measurements may also become an impacting factor for differential diagnoses and for designing new research studies. Full article

Wireless synchronization of the digital signal processing (DSP) features between two hearing aids in a bilateral hearing aid fitting is a fairly new technology. This technology is expected to preserve the differences in time and intensity between the two ears by co-ordinating the bilateral DSP features such as multichannel compression, noise reduction, and adaptive directionality. The purpose of this study was to evaluate the benefits of wireless communication as implemented in two commercially available hearing aids. More specifically, this study measured speech intelligibility and sound localization abilities of normal hearing and hearing impaired listeners using bilateral hearing aids with wireless synchronization of multichannel Wide Dynamic Range Compression (WDRC). Twenty subjects participated; 8 had normal hearing and 12 had bilaterally symmetrical sensorineural hearing loss. Each individual completed the Hearing in Noise Test (HINT) and a sound localization test with two types of stimuli. No specific benefit from wireless WDRC synchronization was observed for the HINT; however, hearing impaired listeners had better localization with the wireless synchronization. Binaural wireless technology in hearing aids may improve localization abilities although the possible effect appears to be small at the initial fitting. With adaptation, the hearing aids with synchronized signal processing may lead to an improvement in localization and speech intelligibility. Further research is required to demonstrate the effect of adaptation to the hearing aids with synchronized signal processing on different aspects of auditory performance. Full article