Detailed clinical features and genotype-phenotype correlation in an OTOF-related hearing loss cohort in Japan.

Mutations in the OTOF gene are a common cause of hereditary hearing loss and the main cause of auditory neuropathy spectrum disorder (ANSD). Although it is reported that most of the patients with OTOF mutations have stable, congenital or prelingual onset severe-to-profound hearing loss, some patients show atypical clinical phenotypes, and the genotype-phenotype correlation in patients with OTOF mutations is not yet fully understood. In this study, we aimed to reveal detailed clinical characteristics of OTOF-related hearing loss patients and the genotype-phenotype correlation. Detailed clinical information was available for 64 patients in our database who were diagnosed with OTOF-related hearing loss. As reported previously, most of the patients (90.6%) showed a "typical" phenotype; prelingual and severe-to-profound hearing loss. Forty-seven patients (73.4%) underwent cochlear implantation surgery and showed successful outcomes; approximately 85-90% of the patients showed a hearing level of 20-39 dB with cochlear implant and a Categories of Auditory Performance (CAP) scale level 6 or better. Although truncating mutations and p.Arg1939Gln were clearly related to severe phenotype, almost half of the patients with one or more non-truncating mutations showed mild-to-moderate hearing loss. Notably, patients with p.His513Arg, p.Ile1573Thr and p.Glu1910Lys showed "true" auditory neuropathy-like clinical characteristics. In this study, we have clarified genotype-phenotype correlation and efficacy of cochlear implantation for OTOF-related hearing loss patients in the biggest cohort studied to date. We believe that the clinical characteristics and genotype-phenotype correlation found in this study will support preoperative counseling and appropriate intervention for OTOF-related hearing loss patients.

[Evaluation of the Effectiveness and Safety in a Multi-center Clinical Trial of VIBRANT SOUNDBRIDGE in Japan].

Middle ear implants (MEIs) such as the Vibrant Soundbridge (VSB) are attractive and alternative treatments for patients with conductive, sensorineural, and mixed hearing loss who do not benefit from, or who choose not to wear, conventional hearing aids (HAs). Recent studies suggest that MEIs can provide better improvements in functional gain, speech perception, and quality of life than HAs, although there are certain risks associated with the surgery which should be taken into consideration, including facial nerve or chorda tympanic nerve damage, dysfunctions of the middle and inner ears, and future device failure/explantation. In Japan, a multi-center clinical trial of VSB was conducted between 2011-2014. A round window vibroplasty via the transmastoid approach was adopted in the protocol. The bony lip overhanging the round window membrane (RWM) was extensively but very carefully drilled to introduce the Floating Mass Transducer (FMT). Perichondrium sheets were used to stabilize the FMT onto the RWM. According to the audiological criteria, the upper limit of bone conduction should be 45 dB, 50 dB, and 65 dB from 500 Hz to 4, 000 Hz. Twenty-five patients underwent the surgery so far at 13 different medical centers. The age at the surgery was between 26-79 years old, and there were 15 males and 10 females. The cause of conductive or mixed hearing loss was middle ear diseases in 23 cases and congenital aural atresia in two cases. The data concerning on the effectiveness and safety of VSB was collected before the surgery and 20 weeks after the surgery. Significant improvements of free-field Pure Tone Audiogram (PTA) from 250 Hz to 8, 000 Hz were confirmed (p < 0.001). Hearing gain up to 40 dB was achieved in the 1, 000 Hz to 4, 000 Hz range. No deterioration in either air conduction or bone conduction at PTA was noted at 20 weeks after the surgery. Monosyllable speech perception in both quiet and noisy conditions improved significantly (p < 0.001). The speech discrimination score in both quiet and noisy conditions improved significantly too (p < 0.001). In the future, it is likely that there will be an increasing population even in Japan that will meet the criteria for MEIs such as VSB. However, the long-term efficacy and safety of these devices should be established.

[Multicenter Clinical Study of Vibrant Soundbridge in Japan: Analysis of Subjective Questionnaires].

The Vibrant Soundbridge (VSB) is an active middle ear implant with the Floating Mass Transducer (FMT). We performed a multicenter study to study the efficacy of the VSB by means of "the 10 Questionnaire on Hearing 2002" and "the APHAB questionnaire" at 13 hospitals between 2011 and 2013. In all, 23 patients with mixed or conductive hearing loss received VSB implantation by the round window placement technique. These individuals were generally unable to use, or gained little from conventional hearing aids or bone conduction hearing aids. Two questionnaires were administrated before the surgery and 20 weeks after the VSB implantation. Scores on every item of "the 10 Questionnaire on Hearing 2002" showed significant improvement under noise after VSB implantation. On the APHAB, the scores for Ease of Communication, Reverberation, and Background subscales improved significantly after the VSB implantation, while the score for the Aversiveness subscale alone failed to show a positive improvement from the inexperience to the new sound. Analysis of the responses to these subjective questionnaires revealed better results after VSB implantation as compared to the preoperative data. In conclusion, RW vibroplasty with the use of VSB provided subjective benefit in patients with conductive and mixed hearing loss.

OTOF mutation screening in Japanese severe to profound recessive hearing loss patients.

BACKGROUND: Auditory neuropathy spectrum disorder (ANSD) is a unique form of hearing loss that involves absence or severe abnormality of auditory brainstem response (ABR), but also the presence of otoacoustic emissions (OAEs). However, with age, the OAEs disappear, making it difficult to distinguish this condition from other nonsyndromic hearing loss. Therefore, the frequency of ANSD may be underestimated. The aim of this study was to determine what portion of nonsyndromic hearing loss is caused by mutations of OTOF, the major responsible gene for nonsyndromic ANSD. METHODS: We screened 160 unrelated Japanese with severe to profound recessive nonsyndromic hearing loss (ARNSHL) without GJB2 or SLC26A4 mutations, and 192 controls with normal hearing. RESULTS: We identified five pathogenic OTOF mutations (p.D398E, p.Y474X, p.N727S, p.R1856Q and p.R1939Q) and six novel, possibly pathogenic variants (p.D450E, p.W717X, p.S1368X, p.R1583H, p.V1778I, and p.E1803A). CONCLUSIONS: The present study showed that OTOF mutations accounted for 3.2-7.3% of severe to profound ARNSHL patients in Japan. OTOF mutations are thus a frequent cause in the Japanese deafness population and mutation screening should be considered regardless of the presence/absence of OAEs.

Long-term speech perception performance in prelingually deafened adult cochlear implant recipients.

To investigate the postoperative long-term outcomes after an average of 9.2 years following cochlear implantation (CI) in prelingually deafened adults, along with preimplantation factors predicting postoperative outcomes.Twenty-six prelingually deafened adults who underwent CI at >18 years were compared with those who had undergone CI in childhood (<9 years) and were >10 years old. Outcome measures includedhearing thresholds, preoperative and postoperative aided hearing level (HL), speech discrimination score (SDS), and Categories of Auditory Performance (CAP) scores. Correlation analyses were performed on the following: SDS results, aided HL, school attendant status, implant manufacturers, and speech processor models.Improvement was achieved in the aided HL and SDS results, although these results were not better than those of the child group. CAP score was also statistically significantly improved after CI. Statistically significant correlation between the preoperative SDS and postoperative HL with CI results was observed. In other words, the better the preoperative SDS results, the better the postoperative SDS results.Prelingually deafened adults achieved considerable improvement through CI. It is important to understand that patients achieving better hearing with a well-fitted hearing aid and good SDS performance before surgery may be good candidates for CI.

Effect of cochlear implants on children's perception and production of speech prosody.

Japanese 5- to 13-yr-olds who used cochlear implants (CIs) and a comparison group of normally hearing (NH) Japanese children were tested on their perception and production of speech prosody. For the perception task, they were required to judge whether semantically neutral utterances that were normalized for amplitude were spoken in a happy, sad, or angry manner. The performance of NH children was error-free. By contrast, child CI users performed well below ceiling but above chance levels on happy- and sad-sounding utterances but not on angry-sounding utterances. For the production task, children were required to imitate stereotyped Japanese utterances expressing disappointment and surprise as well as culturally typically representations of crow and cat sounds. NH 5- and 6-year-olds produced significantly poorer imitations than older hearing children, but age was unrelated to the imitation quality of child CI users. Overall, child CI user's imitations were significantly poorer than those of NH children, but they did not differ significantly from the imitations of the youngest NH group. Moreover, there was a robust correlation between the performance of child CI users on the perception and production tasks; this implies that difficulties with prosodic perception underlie their difficulties with prosodic imitation.

Observation of cortical activity during speech stimulation in prelingually deafened adults with cochlear implantation by positron emission tomography-computed tomography.

OBJECTIVES: We evaluated the cortical activity of 2 successful prelingually deafened adult cochlear implant (CI) users who have been trained by auditory-verbal/oral communication since childhood. METHODS: Changes in regional cerebral blood flow were measured by positron emission tomography using '8F-fluorodeoxyglucose while the subjects were receiving auditory language stimuli by listening to a story. Ten normal-hearing volunteers were observed as age-matched control subjects. RESULTS: In both cases, the auditory-related regions, when compared to same regions in the control subjects, showed hypermetabolism in the left dorsolateral prefrontal cortex and the left precentral gyrus--similar to that in successful CI users who are prelingually deafened children or postlingually deafened adults. Both subjects had the ability to activate these areas, and this ability might be one of the reasons that accounts for such exceptionally good performance in older prelingually deaf CI users. As for the visual-related regions, hypometabolism was observed in Brodmann areas 18 and 19, and this finding might be related to the intensive auditory-verbal/oral education that the subjects had received since childhood. CONCLUSIONS: Despite the limits imposed by the small sample size and the spatial resolution of positron emission tomography, this study yielded insights into the nature of the brain plasticity in prelingually deafened adults who are successful CI users.

Novel ACTG1 mutations in patients identified by massively parallel DNA sequencing cause progressive hearing loss.

Human ACTG1 mutations are associated with high-frequency hearing loss, and patients with mutations in this gene are good candidates for electric acoustic stimulation. To better understand the genetic etiology of hearing loss cases, massively parallel DNA sequencing was performed on 7,048 unrelated Japanese hearing loss probands. Among 1,336 autosomal dominant hearing loss patients, we identified 15 probands (1.1%) with 13 potentially pathogenic ACTG1 variants. Six variants were novel and seven were previously reported. We collected and analyzed the detailed clinical features of these patients. The average progression rate of hearing deterioration in pure-tone average for four frequencies was 1.7 dB/year from 0 to 50 years age, and all individuals over 60 years of age had severe hearing loss. To better understand the underlying disease-causing mechanism, intracellular localization of wild-type and mutant gamma-actins were examined using the NIH/3T3 fibroblast cell line. ACTG1 mutants p.I34M p.M82I, p.K118M and p.I165V formed small aggregates while p.R37H, p.G48R, p.E241K and p.H275Y mutant gamma-actins were distributed in a similar manner to the WT. From these results, we believe that some part of the pathogenesis of ACTG1 mutations may be driven by the inability of defective gamma-actin to be polymerized into F-actin.

Mutational Spectrum and Clinical Features of Patients with LOXHD1 Variants Identified in an 8074 Hearing Loss Patient Cohort.

Variants of the LOXHD1 gene, which are expressed in hair cells of the cochlea and vestibule, have been reported to cause a progressive form of autosomal recessive non-syndromic hereditary hearing loss, DFNB77. In this study, genetic screening was conducted on 8074 Japanese hearing loss patients utilizing massively parallel DNA sequencing to identify individuals with LOXHD1 variants and to assess their phenotypes. A total of 28 affected individuals and 21 LOXHD1 variants were identified, among which 13 were novel variants. A recurrent variant c.4212 + 1G > A, only reported in Japanese patients, was detected in 18 individuals. Haplotype analysis implied that this variation occurred in a mutational hot spot, and that multiple ancestors of Japanese population had this variation. Patients with LOXHD1 variations mostly showed early onset hearing loss and presented different progression rates. We speculated that the varying severities and progression rates of hearing loss are the result of environmental and/or other genetic factors. No accompanying symptoms, including vestibular dysfunction, with hearing loss were detected in this study. Few studies have reported the clinical features of LOXHD1-gene associated hearing loss, and this study is by far the largest study focused on the evaluation of this gene.

OTOF mutation analysis with massively parallel DNA sequencing in 2,265 Japanese sensorineural hearing loss patients.

The OTOF gene (Locus: DFNB9), encoding otoferlin, is reported to be one of the major causes of non-syndromic recessive sensorineural hearing loss, and is also reported to be the most common cause of non-syndromic recessive auditory neuropathy spectrum disorder (ANSD). In the present study, we performed OTOF mutation analysis using massively parallel DNA sequencing (MPS). The purpose of this study was to reveal the frequency and precise genetic and clinical background of OTOF-related hearing loss in a large hearing loss population. A total of 2,265 Japanese sensorineural hearing loss (SNHL) patients compatible with autosomal recessive inheritance (including sporadic cases) from 53 otorhinolaryngology departments nationwide participated in this study. The mutation analysis of 68 genes, including the OTOF gene, reported to cause non-syndromic hearing loss was performed using MPS. Thirty-nine out of the 2,265 patients (1.72%) carried homozygous or compound heterozygous mutations in the OTOF gene. It is assumed that the frequency of hearing loss associated with OTOF mutations is about 1.72% of autosomal recessive or sporadic SNHL cases. Hearing level information was available for 32 of 39 patients with biallelic OTOF mutations; 24 of them (75.0%) showed profound hearing loss, 7 (21.9%) showed severe hearing loss and 1 (3.1%) showed mild hearing loss. The hearing level of patients with biallelic OTOF mutations in this study was mostly severe to profound, which is consistent with the results of past reports. Eleven of the 39 patients with biallelic OTOF mutations had been diagnosed with ANSD. The genetic diagnosis of OTOF mutations has significant benefits in terms of clinical decision-making. Patients with OTOF mutations would be good candidates for cochlear implantation; therefore, the detection of OTOF mutations is quite beneficial for patients, especially for those with ANSD.

Comprehensive analysis of syndromic hearing loss patients in Japan.

More than 400 syndromes associated with hearing loss and other symptoms have been described, corresponding to 30% of cases of hereditary hearing loss. In this study we aimed to clarify the mutation spectrum of syndromic hearing loss patients in Japan by using next-generation sequencing analysis with a multiple syndromic targeted resequencing panel (36 target genes). We analyzed single nucleotide variants, small insertions, deletions and copy number variations in the target genes. We enrolled 140 patients with any of 14 syndromes (BOR syndrome, Waardenburg syndrome, osteogenesis imperfecta, spondyloepiphyseal dysplasia congenita, Stickler syndrome, CHARGE syndrome, Jervell and Lange-Nielsen syndrome, Pendred syndrome, Klippel-Feil syndrome, Alport syndrome, Norrie disease, Treacher-Collins syndrome, Perrault syndrome and auditory neuropathy with optic atrophy) and identified the causative variants in 56% of the patients. This analysis could identify the causative variants in syndromic hearing loss patients in a short time with a high diagnostic rate. In addition, it was useful for the analysis of the cases who only partially fulfilled the diagnostic criteria.

Cochlear implantation on prelingually deafened adults.

OBJECTIVE: To evaluate the validity of cochlear implantation (CI) on prelingually deafened adults who have been trained by auditory-verbal/oral communication since childhood. METHODS: Preoperative and postoperative data was investigated regarding the rehabilitation, hearing level, and educational experience of eight prelingually deafened adults. All eight patients were diagnosed with severe to profound sensorineural hearing loss (preoperative hearing levels were over 100 dB). All used hearing aids (HA) before the age of two and were trained by auditory-verbal/oral communication since childhood. The average age of the patients at the time of their CI operations was 23.3 ranging from 18 to 29 years of age. The average postoperative observation time was 55.4 months ranging from 11 to 90 months. RESULTS: Improvement was achieved not only on the pure-tone hearing threshold, but also in speech perception on tests using the Japanese video speech discrimination score (SDS) system. All of them now use CI very well in their daily lives and play important roles in society. CONCLUSION: It was demonstrated that even prelingually deafened adult patients could achieve considerable improvement through CI when they were trained well by auditory-verbal/oral communications since childhood. The indications of CI for prelingually deafened adults must be determined carefully, but all of them do not have to be rejected only because they are prelingually deafened. In other words, CI could be recommended for prelingually deafened adult patients if they received habilitation well with consistent auditory-verbal/oral training using well-fitted HAs.

WFS1 mutation screening in a large series of Japanese hearing loss patients: Massively parallel DNA sequencing-based analysis.

A heterozygous mutation in the Wolfram syndrome type 1 gene (WFS1) causes autosomal dominant nonsyndromic hereditary hearing loss, DFNA6/14/38, or Wolfram-like syndrome. To date, more than 40 different mutations have been reported to be responsible for DFNA6/14/38. In the present study, WFS1 variants were screened in a large series of Japanese hearing loss (HL) patients to clarify the prevalence and clinical characteristics of DFNA6/14/38 and Wolfram-like syndrome. Massively parallel DNA sequencing of 68 target genes was performed in 2,549 unrelated Japanese HL patients to identify genomic variations responsible for HL. The detailed clinical features in patients with WFS1 variants were collected from medical charts and analyzed. We successfully identified 13 WFS1 variants in 19 probands: eight of the 13 variants were previously reported mutations, including three mutations (p.A684V, p.K836N, and p.E864K) known to cause Wolfram-like syndrome, and five were novel mutations. Variants were detected in 15 probands (2.5%) in 602 families with presumably autosomal dominant or mitochondrial HL, and in four probands (0.7%) in 559 sporadic cases; however, no variants were detected in the other 1,388 probands with autosomal recessive or unknown family history. Among the 30 individuals possessing variants, marked variations were observed in the onset of HL as well as in the presence of progressive HL and tinnitus. Vestibular symptoms, which had been rarely reported, were present in 7 out of 30 (23%) of the affected individuals. The most prevalent audiometric configuration was low-frequency type; however, some individuals had high-frequency HL. Haplotype analysis in three mutations (p.A716T, p.K836T, and p.E864K) suggested that the mutations occurred at these mutation hot spots. The present study provided new insights into the audiovestibular phenotypes in patients with WFS1 mutations.

Clinical characteristics and genotype-phenotype correlation of hearing loss patients with SLC26A4 mutations.

CONCLUSIONS: The present study confirmed the clinical characteristics of patients with SLC26A4 mutations: congenital, fluctuating, and progressive hearing loss usually associated with vertigo and/or goiter during long-term follow-up. This clarification should help to facilitate appropriate genetic counseling and proper medical management for patients with these mutations, but there was no particular genotype-phenotype correlation among them, suggesting that other factors may contribute to such variability. OBJECTIVES: Due to the wide range of phenotypes caused by SLC26A4 mutations, there is controversy with regard to genotype-phenotype correlation. The present study was performed: (1) to determine phenotypic range in patients with biallelic SLC26A4 mutations, and (2) to evaluate whether possible genotype-phenotype correlation exists. SUBJECTS AND METHODS: Phenotypes in 39 hearing loss patients with SLC26A4 mutations were summarized and genotype-phenotype correlation was analyzed. RESULTS: Hearing level varied in the individuals from mild to profound severity. Most of the patients had fluctuating and progressive hearing loss that may have been of prelingual onset. Twenty-four (70.6%) patients had episodes of vertigo, and 10 (27.8%) patients had goiter, which had appeared at age 12 or older. In contrast to such phenotypic variabilities, no apparent correlation was found between these phenotypes and their genotypes.

PET-CT observations of cortical activity in pre-lingually deaf adolescent and adult patients with cochlear implantation.

CONCLUSIONS: The present study yielded useful information concerning pre-lingually deaf adolescents and adults who try or manage to understand languages. PET-CT can provide insights into brain plasticity and elucidate which mode of communication is the most effective for education of such patients. OBJECTIVES: To study the cortical activity in pre-lingually deaf adolescent and adult cochlear implants (CI) users who have been trained in auditory-verbal/oral communication since childhood. METHODS: Using positron emission tomography (PET) and 18F-fluorodeoxyglucose (FDG), brain activities in six pre-lingually and two post-lingually deaf CI users (mean age at CI surgery = , 20.3 years; three males, five females) were compared with those of 10 normal age-matched controls (mean age = 27.1 years). Regional cerebral blood flow changes were measured during an acoustic presentation of a story. RESULTS: In compliant CI users, the number of hypermetabolic auditory-related areas was greater in those who had a CI in their 20s than in those who did so in their adolescence. In poor and non-compliant users, hypermetabolism was not seen in the auditory association area, but in the primary auditory areas (BA41) and the Broca's area (BA45). In post-lingually deaf CI users, no increase in the number of hypermetabolic areas was found in auditory-related regions.

Long-term Outcomes of Cochlear Implantation in Children With Congenital Cytomegalovirus Infection.

OBJECTIVE: To investigate the role of the developmental delay often observed in children with congenital cytomegalovirus (CMV) infection on the improvement of language understanding after cochlear implantation (CI). STUDY DESIGN: Retrospective chart review. PATIENTS: Sixteen children with severe and/or profound hearing loss due to congenital CMV infection (CMV group) and 107 congenitally deaf children (168 ears) without CMV infection as the cause of deafness (non-CMV group). Mean age at which patients underwent CI was 2.9 years in both groups. The mean follow-up period was 7.8 versus 8.2 years, respectively. INTERVENTIONS/MAIN OUTCOME MEASURES: The Enjoji Scale of Infant Analytical Development was used to evaluate/compare pre- and postoperative hearing level, word recognition score, speech discrimination score, and language production and perception skills. The Picture Vocabulary Test-Revised was used to assess vocabulary understanding skill. Correlation between the final vocabulary understanding skill assessment and several factors was also examined. RESULTS: Improvement in hearing thresholds (mean: 106.0 dB) was greater after the first CI, (27-45 dB; mean: 33.8 dB) compared with hearing aid (48-74 dB; mean: 63.1 dB). Similarly, language perception and production were better in the CMV group. However, in the long term, differences between good and poor cases became prominent, especially in children with motor or cognitive delay and brain abnormalities who performed poorly in the CMV group. CONCLUSION: Long-term language perception and production after CI were overall satisfactory in congenital CMV-deafened children. CI was effective, particularly in the absence of CMV-induced disorders. However, this effectiveness was limited in those with motor or cognitive delay.

Round Window Application of an Active Middle Ear Implant: A Comparison With Hearing Aid Usage in Japan.

OBJECTIVE: To report on the safety and efficacy of an investigational active middle ear implant (AMEI) in Japan, and to compare results to preoperative results with a hearing aid. DESIGN: Prospective study conducted in Japan in which 23 Japanese-speaking adults suffering from conductive or mixed hearing loss received a VIBRANT SOUNDBRIDGE with implantation at the round window. Postoperative thresholds, speech perception results (word recognition scores, speech reception thresholds, signal-to-noise ratio [SNR]), and quality of life questionnaires at 20 weeks were compared with preoperative results with all patients receiving the same, best available hearing aid (HA). RESULTS: Statistically significant improvements in postoperative AMEI-aided thresholds (1, 2, 4, and 8 kHz) and on the speech reception thresholds and word recognition scores tests, compared with preoperative HA-aided results, were observed. On the SNR, the subjects' mean values showed statistically significant improvement, with -5.7 dB SNR for the AMEI-aided mean and -2.1 dB SNR for the preoperative HA-assisted mean. The APHAB quality of life questionnaire also showed statistically significant improvement with the AMEI. CONCLUSION: Results with the AMEI applied to the round window exceeded those of the best available hearing aid in speech perception as well as quality of life questionnaires. There were minimal adverse events or changes to patients' residual hearing.

Guidelines for the evaluation of hearing aid fitting (2010).

OBJECTIVE: The methods to evaluate the efficacy of the adjusted hearing aid for a hearing-impaired person are fitting tests. The tests include those presently carried out for evaluating hearing aid fitting, and the methods of testing and evaluation have been published as "Guidelines for the evaluation of hearing aid fitting (2010)" by the Japan Audiological Society. METHODS: Guidelines for the following 8 test methods are presented. (1) Measurements of speech performance-intensity functions and speech recognition scores; (2) Assessment of hearing aid fitting from the aspect of tolerance of environmental noise; (3) Measurement of real-ear insertion gain (measurement of sound pressure levels at the eardrum); (4) Measurement of the hearing threshold level and the uncomfortable loudness level (UCL) in sound pressure level (SPL) with an inserted earphone; (5) Aided threshold test in a sound field (functional gain measurement); (6) Prediction of insertion gain and aided threshold from hearing aid characteristics and the pure tone audiogram; (7) Measurement of speech recognition in noise; (8) Assessment of hearing aid fitting using questionnaires. In the above tests, (1) and (2) are mandatory tests, and (3) to (8) are informative tests. RESULTS: By performing test combinations properly selected from the above 8 tests, the benefits of a hearing aid could be determined. CONCLUSION: The above test methods were useful and valuable in determining the efficacy of the adjusted hearing aid for a hearing-impaired person during clinical practice.