The Assessment of Electrode-Neuron Interface (ENI) in Cochlear Implant Users

The electrode-neuron interface (ENI) plays an important in the outcome with cochlear implants as all cochlear implant-mediated signals should pass through this interface. Telemetry has enabled researchers to study factors affecting the quality and integrity of the interface. These factors may influence electrodes, the path between electrodes and auditory neurons, and spiral ganglion neuron survival. Promising studies on animals regarding such factors have opened new possibilities to identify cochlear implant channels with poor electrode-neuron interface. The results of these studies and similar research on human with focus were discussed in this chapter

Real-ear Unaided Gain in Wrestlers with Unilateral Cauliflower Ear

Background and Aim: Real-Ear Unaided Gain (REUG) can reveal the outer-ear resonance which reflects the effects of body and ear factors. Deformity in the outer ear may change the real-ear unaided responses. Cauliflower ear is a common ear deformity in wrestlers. This study aimed to compare the REUG of normal and cauliflower ear in wrestlers to investigate the frequencies at which the gain may be inaccurate. Methods: Ten male wrestlers with the age ranged from 21 to 31 years participated in this study. The study had within-subject design and only one group. The REUGs was recorded for both ears, normal and cauliflower ears, and the results analyzed. Results: The mean of REUG values were significantly different between the deformed and normal ears. There were two distinct peaks in the REUG curve of the deformed ear, while there was a single peak in that of the normal ear. Conclusion: The differences in the REUG at 2–6 kHz between the deformed and normal ears was seen

The Effects of Type of Fitting, Technology and User Experience on Satisfaction with Hearing Aid Assessed by Persian Version of the MarkeTrak Survey

Background and Aim: Satisfaction with hearing aids is very important for continued use of the device and improving hearing status and quality of lives of people with hearing loss. MarkeTrak survey has been used for many years to track factors influencing satisfaction with hearing aids. This study aimed to make a valid and reliable Persian version of the MarkeTrak survey to measure the effects of type of fitting, experience and technology on hearing aid satisfaction. Methods: After confirmation of validity and reliability of the Persian MarkeTrak, 71 people participate in the study. The effects of bilateral versus unilateral hearing aids (type of fitting), experience and wireless versus non-wireless technology were tested. Results: Bilateral hearing aid users has significantly higher satisfaction rate than unilateral users (65.6±7.2 versus 59.9±17.7). The effects of experience with using hearing aids and type of technology did not reach statistical significance. Conclusion: Higher satisfaction with bilateral hearing aids might result from better sound quality in diverse listening conditions, spatial hearing and directionality with two ears rather than one ear

Typology of Street Substance Users' Communities in Tehran, Iran

Background: There are different street substance users' communities (SSUCs). Typology of SSUCs in Tehran, Iran was approached in this qualitative study.Methods: Using content analysis and saturation principles, 22 street-outreach workers were recruited and interviewed. Data were analyzed using open, axial, and selective coding.Findings: Three types of SSUCs were identified. SSUCs were different in geographic location, the community hierarchy, roles of residents and its function during a 24-hour period. Type 1: surrounded naturally by trees, mountains etc. or located in places like canals that make them not simply reachable, a nonresident smuggler (or a small group of smugglers) has the most power in its hierarchy, works 24 hours with at least two shifts, structured with special roles (nonresident smuggler, the Balancer, sex-worker, seller, armed guard, resident substance users and nonresident costumers). Type 2: mostly located in the city gardens, several nonresident smugglers with limited power, works 16 hours or less in a day, semi-structured with roles of nonresident drug dealer, sex-worker, resident substance users and nonresident costumers. Type 3: houses that their landlords are the resident drug dealers and let the costumers to use drug in the house. The substance users have to leave the house after using drug. The house is open less than 24 hours a day.Conclusion: Strategies for delivering harm reduction services in different types of SSUCs should be modified according to characteristics of these communities

Investigating the Effects of Face Mask on Word Recognition Score Test During the COVID-19 Outbreak: Considerations and Limitations

Introduction: Using personal protective equipment, especially face masks, in the COVID-19 pandemic era may make verbal communication difficult. Furthermore, acoustic changes in mask-wearing conditions may affect speech audiometry results. This study investigates the effect of wearing a face mask on the word recognition score and the role of speech frequency content in this effect. Materials and Methods: This study was planned and conducted in two phases. In the first phase, the validity and reliability of two speech material lists, high-pitch and low-pitch, were determined. In the second phase, the word recognition score was measured for “mask-wearing” and “covering mouth without a mask.” Results: The statistical analysis showed that the content validity ratio was 0.92, and the content validity index was 0.8. Therefore, both speech lists were valid. For these lists, the mixed analysis of variance analysis showed that the scores for “mask-wearing” were significantly lower than “covering mouth without a mask,” and there was more reduction in scores for the high-pitched list (F=8.7, df=1, P<0.005). Conclusion: In terms of the impact of a face mask on speech, explaining how speech audiometry is performed, especially in monitoring treatments, may help limit the probability of misinterpretation of speech test findings. Furthermore, understanding the impact of face masks on word recognition scores in adopting sufficient auditory rehabilitation procedures is necessary

Comparing Sound-Field Speech-Auditory Brainstem Response Components between Cochlear Implant Users with Different Speech Recognition in Noise Scores

ObjectivesMany studies have suggested that Cochlear Implant (CI) users vary in terms of speech recognition in noise. Studies in this field attribute this variety partly to subcortical auditory processing. Since study on speech-Auditory Brainstem Response (speech-ABR) provides good information about speech processing, so this work was designed to compare speech-ABR components between two groups of CI users with good and poor speech recognition in noise scores.Materials &amp; MethodsThe present study was conducted on two groups of CI users aged 8-10 years old. The first group (CI-good) consisted of 15 children prelingual CI users who had good speech recognition in noise performance. The second group (CI-poor) matched with the first group, but they had poor speech recognition in noise performance. The speech-ABR test in a sound-field presentation was performed for all the participants.  Results The speech-ABR response showed more delay in C, D, E, F, O latencies in CI-poor than CI-good users (P &lt;0.05), meanwhile no significant difference was observed in initial wave (V(t= -0.293, p= 0.771 and A(t= -1.051, p= 0.307). Analysis in spectral-domain showed a weaker representation of fundamental frequency as well as the first formant and high-frequency component of speech stimuli in the CI-poor users.ConclusionsResults revealed that CI users who showed poor auditory performance in noise performance had deficits in encoding of periodic portion of speech signals at brainstem level. Also, this study could be as physiological evidence for poorer pitch processing in CI users with poor speech recognition in noise performance

Comparison of the Components of Brainstem Auditory Responses Using Click and Chirp Stimuli in Premature Infants

Background and Objectives: Prematurity means that the baby is born before 37 months of age, which leads to various problems, including hearing defects. Timely detection of hearing loss with the help of tools that facilitate this identification, can have a significant impact on the child’s personal, social, and educational development. The aim of the present study was to achieve better responses using the chirp stimulus along with the click. The chirp stimulus can compensate for the time delay caused by low-frequency stimuli and increases the simultaneous presentation of high and low frequencies in the cochlea. Therefore, the morphology of the waves is improved, and the amplitude of responses increases; thus, the waves can be better identified despite the prematurity of the infants. Methods: Eighy newborns were examined in four groups, which were divided into term and preterm groups based on gestational age (including late preterm, moderate, and very preterm). The intensity of the click and chirp stimuli was fixed at 40 and 80 dB. The amplitude and latency of waves I, III, and V, the inter-peak latencies of I-III, III-V, and I-V, as well as the ratio of the amplitude of wave V/I were among the compared parameters. It should be mentioned in tables paired t-test was used in cases marked with *. Wilcoxon test was used in other cases. Results: The chirp stimulus mainly had less latency than the click stimulus and created a larger amplitude at a high intensity (80 dB). In the intensity close to the threshold, i.e. 40 dB, these findings were slightly different. The more developed the infants, the stronger the responses and the more effective the chirp stimulus in eliciting responses. Conclusion: The chirp stimulus was more effective in obtaining multiple components of brainstem-evoked responses in infants, especially preterm infants, and investigating the status of their auditory system. The use of a higher sample size could lead to an increase in the growth of clinical use and better efficiency of diagnostic protocols and responses

Music perception in bimodal cochlear implant users

© 2014 Dr. Mohammad MaarefvandWhile most cochlear implant users can perceive speech signals in quiet conditions very well, the perception of music is reported to be poor for most of them. In this thesis the perception of music in cochlear implant users was the main focus of the research. It has been found that most cochlear implant users cannot perceive pitches of melodies which are very important to music perception. Another limitation in their perception of music was in the recognition of musical instruments or more generally the timbre of sounds. It is widely believed that the current technology of cochlear implants is suitable only for coding of speech signals and not music signals. There is a need to investigate the reasons for such poor perception of music. The poor perception of pitch is believed to be the main reason for poor music perception. A literature review showed that although pitch perception is not satisfactory in cochlear implant users, there is also a possibility of interference between the perception of pitch and other aspects like intensity and quality of sounds. Therefore in the rest of the research, the effects of these two aspects on the perception of pitch were investigated. Three mechanisms were identified by which intensity could influence the perception of pitch (Current spreading, Electrode activation spreading, and Spectral spreading). Each mechanism was tested by inputting a specific stimulus type to the cochlear implant sound processor at two different intensity levels. Twelve bimodal cochlear implant users were the participants in this part of the research. The perceived pitch was quantified through a selected matched frequency value in the non-implanted ear (bimodal pitch matching). The results showed that the effect of intensity was observed when current spreading happened. Another finding of this research was that the perceived pitches due to stimulating different electrodes of the cochlear implants were lower than Greenwood’s prediction. In addition, when spectral spreading was present in complex musical notes, the perceived pitch for low frequency was not significantly different from that of high frequency. A wide range of frequency created a narrow range of different pitches in the cochlear implant. There were large individual differences among people. Some participants perceived lower pitch at higher intensity while others perceived higher pitch at higher intensity. To test the effect of sound quality on perceived pitch all of the above mechanisms were tested twice: once with a pure tone as the matching sound in the non-implanted ear and again with a complex tone in the non-implanted ear. The matched frequencies using complex tones were significantly lower than their counterparts with pure tones. This showed that the type of sound had a significant effect on the perception of pitch. In addition when pitch matching was done in one ear (monaural pitch matching) and the types of both sounds in matching were completely similar, the participants could match pitch with more precision. This was another indication that sound quality had an effect on the perception of pitch. Monaural pitch matching in the implanted ear showed that the effect of intensity in the implanted ear was greater in comparison with monaural pitch matching in the non-implanted ear. An earlier research study conducted by the author on a star performer indicated that current CIs can provide enough information for pitch perception of sounds from a single instrument when the listener is very familiar with that instrument. Bimodal cochlear implant users may experience different pitch percepts in implanted and non-implanted ears. The implication of this research is that a larger number of electrodes with narrower analysis filters in the sound processor could provide better fine structure information and improve pitch perception. The results suggest that more restricted current spreading could improve pitch perception as well

Gap in Noise Auditory Brainstem Responses: A Systematic Review

Background and Objectives: The gap in noise auditory brainstem responses (GIN-ABR) is a valuable assessment tool for auditory temporal processing, offering non-invasive and objective measurements encompassing the entire auditory system from the cochlea to the brainstem. This method has been utilized in investigating various factors, including age-related effects, hearing loss, and tinnitus. This systematic review was conducted to present a thorough examination of (GIN-ABR), encompassing its methodology, applications, and inherent limitations. Methods: This study was conducted based on preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Cochrane, PubMed, and Ovid databases were used to extract English articles from 1990 to June 2023. The search terms used were “gap in noise auditory brainstem response”, “ABR gap detection”, “ABR gap duration”, “ABR gap threshold”, and “ABR temporal processing”. Articles were included if gap-evoked ABR was used, investigating the effect of any factor on the responses, and using any gapped stimulus type. Articles whose evoked potentials did not include ABR waves were excluded. The outcome of interest was gap-evoked ABR in different participant groups. Results: A total of 10 studies were deemed suitable for inclusion in the review. The articles were reviewed that including the study population, the methods, and the results. Despite the variability in the results of the studies, in the aged group, longer latency shifts and decreased peak amplitude were reported compared to the young group. Correspondence of behavioral thresholds with GIN-ABR has also been mentioned in studies. Conclusion: The GIN-ABR method has been extensively utilized in investigating various factors, including age-related effects, hearing loss, and tinnitus. Notably, GIN-ABR has several clinical advantages, such as cost-effectiveness, shorter test duration, independence from alertness levels, attention, sleep depth fluctuations, or medication. Additionally, it has shown its compatibility with psychophysical tests. Further research is warranted to explore the impact of various factors on different components of GIN-ABR. Consequently, with its promising findings and growing body of research, the gap in noise test has the potential to be gradually integrated into the set of audiological clinical evaluations