Profound Hearing Impairment Research Articles

The Prevalance Of Hearing Loss causing disability among young adult males in Turkey between 2009-2011

Objective: It is reported that the most common cause of disability in the world is hearing loss following intellectual disability. Our aim in this study is to investigate the distribution of the hearing loss caused disability among young adult men having gone through medical examinations for compulsory military service between 2009 and 2011. Methods: This study was a cross-sectional study. We reviewed the prevalence of hearing loss among 1.777.500 people who were referred for medical examination according to Turkish National Military Regulations between 2009 and 2011. The data for this study has been obtained from the Health Department of the Ministry of Defense and studies have been started after acquiring the necessary ethical permissions from the Gulhane Military Medical Academy (GMMA) Ethics Committee. Results: In this cross-sectional study, the prevalence of hearing loss that have become sequela and caused disability (40dB and above) has been identified as 3.32 per thousand in 2009, 3.95 per thousand in 2010 and 3.86 per thousand in 2011. The most common subtypes of hearing loss are unilateral profound hearing impairment including deafness (one ear normal, the other one with 90dB and above hearing loss) (28.9%), bilateral severe hearing impairment (65 dB or more hearing loss) (25.3%) and bilateral moderate hearing impairment (40-65 dB hearing loss) (19.3%). Conclusion: Although mostly acute infectious diseases have been observed in infancy and childhood, these diseases may become sequela at the level of disability in older ages (in advancing ages). Incidence of the disability can be reduced by early diagnosis and appropriate treatment especially during infancy and childhood.

Using a cochlear implant in the rehabilitation of people with profound hearing impairment

The article reveals thoroughly the conditions and rules for effective use of cochlear implantation method for rehabilitation of children with the profound hearing impairment. Outlined the factors and components of rehabilitation, the role of parents in the process of rehabilitation. Today, to help people with profound hearing loss by using cochlear implantation. Its aim is the socialization of children. The effectiveness of cochlear prosthesis depends on many factors, one of which is the age of the child, early detection, and timely hearing aid. Proved that early started with hearing and speech development and early age of the child when implanted lead to the best results. It is therefore most appropriate for the cochlear prosthesis is the age of two years. In this case, the optimal rehabilitation results can be achieved in under 3 years. The cochlear implant allows it to hear all the carriers, but the efficiency understanding of language as a means of communication in all different. Quite important mission in the successful auditory and speech rehabilitation of children belongs to the parents and relatives. The participation of parents in this process and their psychological and social support to a child is one of the essential components of the entire system before and after surgery. They regularly take part in various rehabilitation activities in accordance with the recommendations of experts. Their joint work has kept to ensuring that at the end of preschool children in their development reached the level of hearing peers. This will give them the ability to learn in school. The prerequisites for such integration is its ample hearing and mental abilities.

Prevalence and causes of hearing impairment in Africa.

To systematically assess the data on the prevalence and causes of hearing impairment in Africa. Systematic review on the prevalence and causes of hearing loss in Africa. We undertook a literature search of seven electronic databases (EMBASE, PubMed, Medline, Global Health, Web of Knowledge, Academic Search Complete and Africa Wide Information) and manually searched bibliographies of included articles. The search was restricted to population-based studies on hearing impairment in Africa. Data were extracted using a standard protocol. We identified 232 articles and included 28 articles in the final analysis. The most common cut-offs used for hearing impairment were 25 and 30 dB HL, but this ranged between 15 and 40 dB HL. For a cut-off of 25 dB, the median was 7.7% for the children- or school-based studies and 17% for population-based studies. For a cut-off of 30 dB HL, the median was 6.6% for the children or school-based studies and 31% for population-based studies. In schools for the deaf, the most common cause of hearing impairment was cryptogenic deafness (50%) followed by infectious causes (43%). In mainstream schools and general population, the most common cause of hearing impairment was middle ear disease (36%), followed by undetermined causes (35%) and cerumen impaction (24%). There are very few population-based studies available to estimate the prevalence of hearing impairment in Africa. Those studies that are available use different cut-offs, making comparison difficult. However, the evidence suggests that the prevalence of hearing impairment is high and that much of it is avoidable or treatable.

SLC39A8 Deficiency: A Disorder of Manganese Transport and Glycosylation

SLC39A8 is a membrane transporter responsible for manganese uptake into the cell. Via whole-exome sequencing, we studied a child that presented with cranial asymmetry, severe infantile spasms with hypsarrhythmia, and dysproportionate dwarfism. Analysis of transferrin glycosylation revealed severe dysglycosylation corresponding to a type II congenital disorder of glycosylation (CDG) and the blood manganese levels were below the detection limit. The variants c.112G>C (p.Gly38Arg) and c.1019T>A (p.Ile340Asn) were identified in SLC39A8. A second individual with the variants c.97G>A (p.Val33Met) and c.1004G>C (p.Ser335Thr) on the paternal allele and c.610G>T (p.Gly204Cys) on the maternal allele was identified among a group of unresolved case subjects with CDG. These data demonstrate that variants in SLC39A8 impair the function of manganese-dependent enzymes, most notably β-1,4-galactosyltransferase, a Golgi enzyme essential for biosynthesis of the carbohydrate part of glycoproteins. Impaired galactosylation leads to a severe disorder with deformed skull, severe seizures, short limbs, profound psychomotor retardation, and hearing loss. Oral galactose supplementation is a treatment option and results in complete normalization of glycosylation. SLC39A8 deficiency links a trace element deficiency with inherited glycosylation disorders.

Functional Analysis of a Novel Connexin30 Mutation in a Large Family with Hearing Loss, Pesplanus, Ichthyosis, Cutaneous Nodules, and Keratoderma.

Mutations in the gap-junction gene Cx30 (Connexin30, GJB6) are a known cause of hearing loss. Here, we report our findings on a large multigeneration family in which severe to profound sensorineural hearing impairment is associated with a variety of skin-related anomalies. Genome-wide analysis of the family showed that the locus maps to chromosome region 13ptel-q12.1 and that a novel mutation, p.N54K, in Cx30, cosegregates with the phenotype. Unlike wild-type Cx30, p.N54K Cx30 is predominantly localized in the cytoplasm and does not permit transfer of neurobiotin, suggesting improper cellular localization and abolishment of gap-junction activity.

Comparison: real and simulated ear insertion gain

AbstractThe development of hearing aid (HA) software programming does not replace the analysis of real ears with probe microphones. AimTo compare simulated insertion gain in HA software programming and real ear insertion gain. MethodA prospective study of 62 patients (aged from 29 to 93 years; 30 male and 32 female). All patients presented unilateral (n=14) or bilateral (n=48) and mild to profound sensorineural hearing impairment. 110 ears assessed. Data was gathered from medical records and the insertion gain was obtained in real ears for comparison with the simulated insertion gain in HA software programming. Statistical tests were applied to analyze the correlation of data - difference of real ear and simulated insertion gain. ResultsHA software programming simulated insertion gain was higher than real ear insertion gain obtained with probe microphone measures. There were statistically significant frequency differences. Age did not correlate with the difference of real ear and simulated measures. ConclusionThe use of real ear measures is important during verification of HA.

Identifying Children With Poor Cochlear Implantation Outcomes Using Massively Parallel Sequencing.

Cochlear implantation is currently the treatment of choice for children with severe to profound hearing impairment. However, the outcomes with cochlear implants (CIs) vary significantly among recipients. The purpose of the present study is to identify the genetic determinants of poor CI outcomes. Twelve children with poor CI outcomes (the “cases”) and 30 “matched controls” with good CI outcomes were subjected to comprehensive genetic analyses using massively parallel sequencing, which targeted 129 known deafness genes. Audiological features, imaging findings, and auditory/speech performance with CIs were then correlated to the genetic diagnoses. We identified genetic variants which are associated with poor CI outcomes in 7 (58%) of the 12 cases; 4 cases had bi-allelic PCDH15 pathogenic mutations and 3 cases were homozygous for the DFNB59 p.G292R variant. Mutations in the WFS1, GJB3, ESRRB, LRTOMT, MYO3A, and POU3F4 genes were detected in 7 (23%) of the 30 matched controls. The allele frequencies of PCDH15 and DFNB59 variants were significantly higher in the cases than in the matched controls (both P < 0.001). In the 7 CI recipients with PCDH15 or DFNB59 variants, otoacoustic emissions were absent in both ears, and imaging findings were normal in all 7 implanted ears. PCDH15 or DFNB59 variants are associated with poor CI performance, yet children with PCDH15 or DFNB59 variants might show clinical features indistinguishable from those of other typical pediatric CI recipients. Accordingly, genetic examination is indicated in all CI candidates before operation.

Symptoms of Psychopathology in Hearing-Impaired Children.

Objectives:Children with hearing loss are at risk of developing psychopathology, which has detrimental consequences for academic and psychosocial functioning later in life. Yet, the causes of the extensive variability in outcomes are not fully understood. Therefore, the authors wanted to objectify symptoms of psychopathology in children with cochlear implants or hearing aids, and in normally hearing peers, and to identify various risk and protective factors.Design:The large sample (mean age = 11.8 years) included three subgroups with comparable age, gender, socioeconomic status, and nonverbal intelligence: 57 with cochlear implants, 75 with conventional hearing aids, and 129 children who were normally hearing. Psychopathology was assessed by means of self- and parent-report measures.Results:Children with cochlear implants showed similar levels of symptoms of psychopathology when compared with their normally hearing peers, but children with hearing aids had significantly higher levels of psychopathological symptoms, while their hearing losses were approximately 43 dB lower than those of children with implants. Type of device was related with internalizing symptoms but not with externalizing symptoms. Furthermore, lower age and sufficient language and communication skills predicted less psychopathological symptoms.Conclusions:Children who are deaf or profoundly hearing impaired and have cochlear implants have lower levels of psychopathological symptoms than children with moderate or severe hearing loss who have hearing aids. Most likely, it is not the type of hearing device but rather the intensity of the rehabilitation program that can account for this difference. This outcome has major consequences for the next generation of children with hearing loss because children with profound hearing impairment still have the potential to have levels of psychopathology that are comparable to children who are normally hearing.

Consonant discrimination by Mandarin-speaking children with prelingual hearing impairment

ObjectivesLittle is known about the consonant discrimination ability of Mandarin-speaking children with prelingual hearing impairment (HI) and fitted with hearing aids (HAs). The present study aimed to evaluate Mandarin consonant discrimination ability in children with HI, and explore the effects of unaided and aided hearing threshold, the age of first HA fitting and the duration of HA use on consonant discrimination ability. MethodsSubjects were Mandarin-speaking children aged 5;4–12;6 years with profound HI (n=41), children aged 6;1–12;4 years with severe HI (n=26), and children aged 5;0–11;9 years with moderate HI (n=9). The Mandarin Consonant Discrimination Test was administered in six test conditions: −10, −5, 0, 5 and 10dB signal to noise ratios (S/Ns) and quiet. HAs were in the usual user's settings, adjusted to match the manufacturer prescribed settings and individual preferences, and the volume was set to comfortable listening level. ResultsThe results revealed that /ph/-/th/, /ts/-/tʂ/ and /ʐ/-/l/ were the most difficult and /p/-/ph/, /t/-/th/, /tɕ/-/tɕh/ and /k/-/kh/ were the easiest consonant minimal pairs to discriminate in quiet both for children with profound HI and those with moderate to severe HI. In noise, no significant difference in performance was found among all consonant minimal pairs. A backward elimination stepwise multiple linear regressions revealed that unaided hearing level accounted for 25.4% of the variance in consonant discrimination performance in noise at 10dB S/N and 30.4% in quiet. However, aided hearing threshold, the age of first HA fitting and the duration of HA use did not significantly predict consonant discrimination ability both in quiet and in noise. ConclusionsConsonant discrimination performance of children with profound HI was poorer than those with moderate to severe HI. The ability to discriminate consonant pairs seems to depend on age of acquisition of the consonants. Although the age of first HA fitting and the duration of HA use were not correlated with consonant discrimination outcomes, this finding does not preclude the importance of early HA fitting.

Management challenges of congenital & early onset childhood hearing loss in a sub-Saharan African country

BackgroundHearing impairment is a hidden human disability with potentially catastrophic and age long consequences. This study highlighted the challenges associated with the management of congenital and early onset childhood hearing loss in a sub-Saharan African country. MethodsA retrospective descriptive study of children seen between January 2008 and December 2013 ResultA total of 223 children consisting of 124 (55.6%) males with (M:F) of 1.3:1. Age ranged 1–15 years (mean±SD; 6.39±4.37 years) and age group 1–5 years constituted the largest proportion (56.5%). Congenital causes, febrile illness and hypoxia were the leading causes of HI. Over 93% had moderately severe to profound hearing loss and 64.6% had delayed speech development. Majority (99.3%) with congenital/perinatal onset of HL had significantly delayed speech development and 99.3% of HL due to ototoxicity and infective causes had peri/post lingual speech impairment. Larger percentage of patients presented late; 16.6% of patients with congenital/perinatal onset of HL presented within the first year, >41% presented after the fifth year. Less than 5% had hearing aid fitted and patients with profound hearing impairment were referred for cochlear implant ConclusionThe burden of congenital and early onset hearing impairment is high and management outcomes are unsatisfactory in our locality, Challenges associated with managing such children were discussed, and suggestions/strategies for better management and outcome were made.

A Comparison of Persian Vowel Production in Hearing-Impaired Children Using a Cochlear Implant and Normal-Hearing Children

Normal-hearing (NH) acuity and auditory feedback control are crucial for human voice production and articulation. The lack of auditory feedback in individuals with profound hearing impairment changes their vowel production. The purpose of this study was to compare Persian vowel production in deaf children with cochlear implants (CIs) and that in NH children. The participants were 20 children (12 girls and 8 boys) with age range of 5 years; 1month to 9years. All patients had congenital hearing loss and received a multichannel CI at an average age of 3years. They had at least 6months experience of their current device (CI). The control group consisted of 20 NH children (12 girls and 8boys) with age range of 5 to 9years old. The two groups were matched by age. Participants were native Persian speakers who were asked to produce the vowels /i/, /e/, /ӕ/, /u/, /o/, and /a/. The averages for first formant frequency (F1) and second formant frequency (F2) of six vowels were measured using Praat software (Version 5.1.44, Boersma & Weenink, 2012). The independent samples t test was conducted to assess the differences in F1 and F2 values and the area of the vowel space between the two groups. Mean values of F1 were increased in CI children; the mean values of F1 for vowel /i/ and /a/, F2 for vowel /a/ and /o/ were significantly different (P<0.05). The changes in F1 and F2 showed a centralized vowel space for CI children. F1 is increased in CI children, probably because CI children tend to overarticulate. We hypothesis this is due to a lack of auditory feedback; there is an attempt by hearing-impaired children to compensate via proprioceptive feedback during articulatory process.

External ear anomalies and hearing impairment in Noonan Syndrome

ObjectiveThis is the first cohort in which hearing impairment and external ear anomalies in Noonan Syndrome are described extensively. MethodsRetrospective analysis of the otorhinolaryngological and clinical genetic data from 97 Noonan Syndrome (NS) patients. Forty-four NS patients were seen by an otorhinolaryngologist for the analysis of hearing impairment. In our cohort 80 of the 97 patients were genetically tested. In 71 of these mutations were found: in 48 patients a mutation in PTPN11, in 10 patients in SOS1, in 5 patients in SHOC2, in 5 patients in RAF1, in 1 patient in MAP2K2, in 1 patient in KRAS and in 1 patient in A2ML1. ResultsExternal ear anomalies were reported in 75 NS patients (77%). In 69 patients the ears were low-set, 28 patients had posteriorly rotated ears, 14 patients showed protruding ears and 18 had thickened helices. Hearing impairment was detected in 34 NS patients. Nine patients had sensorineural hearing impairment, two a permanent conductive hearing impairment, two other patients had mixed hearing impairment and 20 patients had conductive hearing impairment in the past, caused by otitis media with effusion. Their temporary conductive hearing impairment resolved between the ages of 2 and 18 years. Sensorineural hearing impairment varied between mild high-frequency hearing impairment and profound (uni- and bilateral) hearing impairment and was progressive in three patients. Four NS patients received cochlear implants for their severe sensorineural hearing impairment. The cohort is small for genotype–phenotype correlations, but sensorineural hearing impairment, especially the bilateral severe hearing impairment, was only seen in patients with a PTPN11 mutation. ConclusionNS is characterized by dysmorphic external ear anomalies and both sensorineural and conductive hearing impairment. Audiological examinations are recommended in all patients with Noonan Syndrome.

Newborn hearing screening: analysis and outcomes after 100,000 births in Upper-Normandy French region

ObjectivesNeonatal hearing impairment is a common disorder with a prevalence of 1 to 2‰ worldwide, with significant consequences on overall development when rehabilitated too late. New-born hearing screening has been implemented in the 1990s in most European countries and the USA. The Upper-Normandy region of France has been conducting a pilot program since 1999. The aim of this prospective study was to evaluate and critically analyse it. MethodsThe Upper-Normandy universal new-born hearing screening program is performed in two steps. Between 1999 and 2004, first, we administered a Transient Evoked Oto Acoustic Emission (TEOAE) test was administered a few days after birth for healthy newborns without risk factors. For newborns admitted to a neonatal intensive care unit (NICU) or presenting risk factors, was administered an automated auditory brainstem response (AABR) test prior to discharge. Second, newborns who failed the initial hearing screening were retested as outpatients using TEOAE. Since 2004, infants who failed the initial screen were tested with AABR 3 to 4 weeks later as outpatients, providing an opportunity to compare the two protocols. ResultsOverall screening coverage in the Upper-Normandy region is 99.8%. First step coverage is 99.58% in well-infant nurseries and 97.09% in the NICU. The test–retest procedure during the first step and the use of AABR for the second resulted in higher follow-up rates and lower false positive rates. ConclusionsThe Upper-Normandy region universal newborn hearing screening program facilitated diagnosis and rehabilitation of infants before age of 9 months, most notably when severe to profound hearing impairment was found.

Safety and feasibility of initial frequency mapping within 24 hours after cochlear implantation

Conclusion: Switch-on within 24 h after cochlear implantation can be safely and practically performed. The minimally invasive approach presented here also brought about benefits such as nonstop rehabilitation programs and shorter duration of uncertainty/worry for patients and their families about surgical outcomes. Those were important factors for international patients. Our research invites further studies to show whether instant commencement of electrical stimulation helps to expedite long-term hearing/speech performance in cochlear implantees. Objectives: Initial switch-on generally could not launch until weeks after cochlear implantation due to factors associated with wound conditions. Commencement of electrical stimulation within 24 h after the surgery has long been performed in our department on a routine basis. The idea issued from the need to sew-and-go for international patients. This study presents the safety and feasibility of the procedure. Methods: Charts of 79 subjects with profound hearing impairment were studied. A minimally invasive approach was used for cochlear implantation, with an intention to control wound condition and tissue swelling. Hearing threshold was measured preoperatively and postoperatively. Results: Initial switch-on within 24 h was done in all patients. Good hearing gain was obtained. No major complication occurred. There was no significant difference in hearing postoperatively that was attributable to the early switch-on.

Evidence for Central Asian Origin of the p.Val27Ile Variant in the GJB2 Gene

The mutations in the GJB2 gene are the most common cause of nonsyndromic hearing impairment and they are associated with the population’s ethnic background. The p.Val27Ile is frequent in both Asia and America. In this retrospective study, we report the findings from the GJB2 screening and the audiological exams conducted on 125 Mexican mestizo patients with non-syndromic hearing impairment; they were treated at the Instituto Nacional de Rehabilitacion in Mexico City. The most frequent audiometric findings were bilateral, symmetrical, and profound hearing impairment. The allele frequencies in the GJB2 screening were p.Val27Ile 15%, other mutations 5%, and wild type 80%. We found no correlation between GJB2 genotype and auditory phenotype. The high allele frequency of p.Val27Ile was a very interesting finding. Our research suggests that p.Val27Ile arose in an ancient common ancestor who lived in Altai Republic and then the polymorphism was brought to America by its first inhabitants, the Amerindians. These results enhance our understanding of the peopling of the America, which remains unresolved.

Delayed auditory pathway maturation and prematurity.

Hearing loss is the most common sensory disorder in developed countries and leads to a severe reduction in quality of life. In this uncontrolled case series, we evaluated the auditory development in patients suffering from congenital nonsyndromic hearing impairment related to preterm birth. Six patients delivered preterm (25th-35th gestational weeks) suffering from mild to profound congenital nonsyndromic hearing impairment, descending from healthy, nonconsanguineous parents and were evaluated by otoacoustic emissions, tympanometry, brainstem-evoked response audiometry, and genetic testing. All patients were treated with hearing aids, and one patient required cochlear implantation. One preterm infant (32nd gestational week) initially presented with a 70 dB hearing loss, accompanied by negative otoacoustic emissions and normal tympanometric findings. The patient was treated with hearing aids and displayed a gradual improvement in bilateral hearing that completely normalized by 14 months of age accompanied by the development of otoacoustic emission responses. Conclusions We present here for the first time a fully documented preterm patient with delayed auditory pathway maturation and normalization of hearing within 14 months of birth. Although rare, postpartum development of the auditory system should, therefore, be considered in the initial stages for treating preterm hearing impaired patients.

Congenital cytomegalovirus infection is a significant cause of moderate to profound sensorineural hearing loss in Queensland children.

To investigate the proportion of children with moderate to profound hearing loss who have congenital cytomegalovirus (cCMV) infection. Retrospective analysis of CMV dried blood spot (DBS) polymerase chain reaction (PCR) in children with moderate to profound hearing impairment referred to tertiary referral centres in Queensland. Participants were under 18 years old with no readily identified cause of hearing impairment, between 2008 and 2011. The primary outcome measure was DBS CMV PCR. Other outcome measures for cases referred to the Childhood Hearing Clinic (CHC) at the Mater Children's Hospital were level of hearing impairment and the neonatal hearing screen result. Of DBS CMV PCR testing for 106 children at the CHC for 2008 to 2011 inclusive, nine (8.5%) were positive (five with bilateral hearing impairment, four with unilateral hearing impairment). The prevalence of cCMV infection in children with moderate to profound hearing impairment was 8.4%, consistent with the statewide rate of 9.4% for 2008 to mid-2011. cCMV is a significant cause of hearing impairment in Queensland children. Investigation for cCMV by retrospective DBS CMV PCR should be part of the routine investigation of all babies and young children with hearing impairment. However early diagnosis is preferable and could be achieved by routine early screening of all newborns with hearing impairment for CMV before 3 weeks of age. The healthy hearing screening programme is a routine part of neonatal care. Enhancing the integration of screening for cCMV may reduce the current delays in diagnosis and should be evaluated.

Severe to profound hearing impairment: quality of life, psychosocial consequences and audiological rehabilitation

Purpose: To study the quality of life (QoL) and psychosocial consequences in terms of sick leave and audiological rehabilitation given to patients with severe to profound hearing impairment. Method: A retrospective study of data on 2319 patients with severe to profound hearing impairment in The Swedish Quality Register of Otorhinolaryngology, followed by a posted questionnaire including The Hospital Anxiety and Depression Scale (HADS). Results: The results indicate greater levels of anxiety and depression among patients with severe or profound hearing impairment than in the general population, and annoying tinnitus and vertigo had strong negative effects on QoL. The proportion of sick leave differed between the studied dimensions in the study. The proportion of patients who received extended audiological rehabilitation was 38% in the present study. Conclusions: Treatment focused on anxiety, depression, tinnitus and vertigo must be given early in the rehabilitation process in patients with severe or profound hearing impairment. Because sick leave differs greatly within this group of patients, collaboration with the regional Social Insurance Agency is crucial part of the rehabilitation. The study also shows that presently, only a small proportion of patients in Sweden with severe to profound hearing impairment receive extended audiological rehabilitation.Implications for RehabilitationGreater levels of anxiety and depression have been found among patients with severe or profound hearing impairment than in the general population, and annoying tinnitus and vertigo have strong negative effects on QoL in this group of patients.Only a small proportion of patients with severe to profound hearing impairment receive extended audiological rehabilitation today, including medical, technical and psychosocial efforts.Extended audiological rehabilitation focused on anxiety, depression, tinnitus and vertigo must be given, together with technical rehabilitation, early in the rehabilitation process in patients with severe or profound hearing impairment.

Tone identification in Mandarin-speaking children with profound hearing impairment

ObjectivesLittle is known about the tone identification ability of Mandarin-speaking children with profound hearing impairment (HI) and fitted with hearing aids (HAs). The present study aimed to evaluate the Mandarin tone identification ability in children with profound HI and fitted with HAs, and explore the effects of hearing thresholds, the age of first HA fitting and the duration of HA use on Mandarin tone identification ability. MethodsSubjects were Mandarin-speaking children aged 5;4–12;6 years with profound HI (n=41). The Mandarin Tone Identification Test was administered in five test conditions: in −10, −5, 0 and 5dB signal-to-noise ratios (S/Ns) and quiet. Hearing aids were in the usual user's settings, optimized for the best speech reception, and the volume was set to comfortable listening level. ResultsTwo-way repeated measures ANOVA showed significant effects of test conditions and tone contrasts in Mandarin tone identification. Post-hoc pairwise comparisons showed significant difference in performance among the five test conditions. Results also indicated that, among the six tone contrasts, the Tone 1/Tone 2 and Tone 2/Tone 3 contrasts were the most difficult tone contrasts in quiet. No significant difference in performance was found among the six tone contrasts in noise. Pearson product-moment correlation showed that the age of first HA fitting, the duration of HA use, aided and unaided average thresholds as well as the aided hearing thresholds in the low frequency region were not significantly correlated with tone identification ability in the five test conditions. ConclusionsConsistent with previous findings, the Tone 1/Tone 2 and Tone 2/Tone 3 contrasts were the most difficult to identify in quiet; but the presence of noise resulted in these tone contrasts being equally difficult. Findings also suggest that the tone identification ability of children with profound HI needs to be improved. Although the age of first HA fitting and the duration of HA use were not significantly correlated with tone identification performance in children with profound HI, this finding does not preclude the importance of early HA fitting.

Cochlear implantation (CI) for prelingual deafness: the relevance of studies of brain organization and the role of first language acquisition in considering outcome success.

Cochlear implantation (CI) for profound congenital hearing impairment, while often successful in restoring hearing to the deaf child, does not always result in effective speech processing. Exposure to non-auditory signals during the pre-implantation period is widely held to be responsible for such failures. Here, we question the inference that such exposure irreparably distorts the function of auditory cortex, negatively impacting the efficacy of CI. Animal studies suggest that in congenital early deafness there is a disconnection between (disordered) activation in primary auditory cortex (A1) and activation in secondary auditory cortex (A2). In humans, one factor contributing to this functional decoupling is assumed to be abnormal activation of A1 by visual projections—including exposure to sign language. In this paper we show that that this abnormal activation of A1 does not routinely occur, while A2 functions effectively supramodally and multimodally to deliver spoken language irrespective of hearing status. What, then, is responsible for poor outcomes for some individuals with CI and for apparent abnormalities in cortical organization in these people? Since infancy is a critical period for the acquisition of language, deaf children born to hearing parents are at risk of developing inefficient neural structures to support skilled language processing. A sign language, acquired by a deaf child as a first language in a signing environment, is cortically organized like a heard spoken language in terms of specialization of the dominant perisylvian system. However, very few deaf children are exposed to sign language in early infancy. Moreover, no studies to date have examined sign language proficiency in relation to cortical organization in individuals with CI. Given the paucity of such relevant findings, we suggest that the best guarantee of good language outcome after CI is the establishment of a secure first language pre-implant—however that may be achieved, and whatever the success of auditory restoration.