British journal of audiology最新文献

A degree of judgement is required when applying the British Standard associated with the calibration and performance of audiometers, BS EN 60645-1 (IEC 645-1). Consequently there is potential for variation of practice between calibration agencies. This note addresses issues and makes suggestions relating to the measurement of distortion, on-off effect, cross talk, linearity, rise/fall time and to the positioning of the earphone on an artificial ear. The degree of precision appropriate to each measurement is suggested. A warning is given of the audiological consequences of excessive distortion produced by normally functioning audiometers.

The Nottingham Paediatric Cochlear Implant Programme (NPCIP) specializes in the cochlear implantation of children under the age of 5 years. The initial stage in the pre-implant evaluation process is audiological assessment. In complex paediatric cases, behavioural audiological assessment may be difficult. In such cases, an objective measure to verify the aided hearing threshold is desirable. This study compares unaided and aided hearing thresholds, by both objective and behavioural techniques, in 20 children (aged <1-10 years). Objective data were collected from auditory brainstem responses (ABR) and behavioural thresholds were measured by use of developmental age-appropriate tests. When comparing the unaided ABR click threshold to the behavioural threshold (obtained from the average of 1-4 kHz warble tones) the ABR threshold was, on average, 9 dB lower (more sensitive). Using the same comparison for aided responses a difference of <5 dB was observed. Unaided ABR thresholds resulted in 35% of subjects responding to the click stimulation (when using a maximum stimulation level of 105 dB nHL), whereas introducing aided ABR measurement elicited positive results in 75% of subjects. The effect of the hearing aid on the stimulus was measured by use of a 2 cc coupler which was connected to a precision sound level meter, whose AC output was recorded onto digital audiotape. Analysis of the resultant output spectra in the frequency domain highlighted signal non-linearity and distortion when using high-intensity stimuli with moderate to high aid gains. In conclusion, aided ABR thresholds are valuable in the management of young children. However, when performing either ABR or behavioural aided hearing threshold measurements it is essential to be aware of the limitations of the hearing aid and the stimulus.

The Nottingham Paediatric Cochlear Implant Programme (NPCIP) specializes in the implantation of children under 5 years of age. Subsequent tuning of the device and identification of changes in device function for these young children, who may have additional disabilities, can often be challenging. Thus, an objective measure to assess the integrity of the device is desirable. This study compares the device function by both objective and behavioural techniques in 30 children (age at implantation 3-11 years) at five years post-implantation. All children were implanted with the Nucleus Mini 22 device. Objective data were collected from integrity testing (IT) which allowed examination of the functioning of the implant by measuring the electrical stimulus artefact. This does not require the child to give a behavioural response. A protocol for a five-year post-implantation IT is suggested which examines common ground, monopolar and bipolar modes of operation. Behavioural data in the form of threshold (T) and comfort (C) levels were obtained by use of developmental age-appropriate techniques at 5 years post-implantation. Results demonstrate that 43.3% of patients had no electrode faults, 23.3% had potential faults on both behavioural and integrity testing, 6.7% were difficult to assess in terms of defining electrode faults due to partial electrode insertions, 13.3% had potential faults on behavioural testing only and 13.3% of patients had potential faults on IT only. In conclusion, IT is valuable in the identification of faulty electrodes, especially in young children and those with additional disabilities. Implementation of the five-year routine IT affected the management of 30% of patients. This study demonstrates that objective and behavioural techniques are complementary procedures in the ongoing management of paediatric patients.

The performance of children who receive a cochlear implant may be dependent on both age of the child at implantation and the amount of experience with the implant. In the present study, changes in auditory perception and speech identification were investigated with experience of 71 children who had received a cochlear implant. The children were divided into three groups, those above and those below the age of 7 years at the time of implantation, and those aged 3 years or younger deafened by meningitis. The children received either the Nucleus 22, the Nucleus 24 or the Med El C40+ implant. The test material was a reduced form of the EARS evaluation protocol developed by Med El into a multi-language format. Tests were performed pre-operatively, within 2-5 days of first fitting of the speech processor, then at 1, 3 and 6 months and every 6 months thereafter, for a total period of 24 months. The results indicated that all children showed improvement after 6-12 months. The rate of improvement differed between age groups. Children over 7 years of age had pre-operatively higher test scores than younger children, presumably because of their previous experience with hearing aids. These children showed an immediate post-operative drop in performance that recovered 1-3 months later. The children aged under 7 years started at lower performance levels but approached those of the older children after 12 months' cochlear implant use because their post-operative drop was less significant and their performance improved faster. Children who had been deafened by meningitis and implanted at the age of 3 or less made little progress over the first 6 months but approached test levels of the under-7-year-olds by 18 months or later. All three components of the evaluation protocol employed the Listening Progress Profile (LiP), the Monosyllabic-Trochee-Polysyllabic Test (MTP) and the Meaningful Auditory Integration Scale (MAIS) and proved to be valuable in demonstrating improvement in performance of cochlear implant children in all age groups once the immediate post-operative drop had been overcome.

This study investigated the effects of sample size on the test-retest reliability of the amplitude of distortion product otoacoustic emissions (DPOAE) (2f1-f2) and on the noise floor. Four pairs of primary frequencies (fl and f2) with geometric means of 531, 1000, 2000 and 4000 Hz were presented to 55 normal-hearing women at intensity levels of 35, 45 and 55 dB SPL (L1 = L2). Sample sizes of 12, 25, 50, 100, 200 and 400 sweeps were averaged. The results revealed that sample size, frequency, and intensity had little effect on the standard error of measurement. Thus, the DPOAE data were combined across all conditions and yielded a standard error of measurement of 2.2 dB. To assess whether two DPOAE measurements are statistically significant (e.g. before and after drug administration), the standard error of measurement of the difference between two values was calculated (3.1 dB). Thus, by use of the 95% confidence interval, the difference between two DPOAE is statistically significant if it exceeds approximately 6 dB.

The aim of the present study was to investigate the validity of a community-based hearing test to detect conductive hearing loss in 3-year-old children. Sixty-five children had their hearing tested using standard audiological tests at the same time as they underwent their 3-year-old health checks. The checks were performed by health visitors at community health clinics, and included the McCormick Toy Test (MCTT) for hearing. Fourteen children failed both tests and none passed the MCTT and failed the standard tests, giving a sensitivity of 100%. Forty-eight children passed both tests and three children failed the MCTT but passed the standard tests, giving a specificity of 94%. Positive predictive value was 82%. The results from this sample indicate that the MCTT may be used as a valid test for conductive hearing loss for 3-year-old children in the community setting.

King-Kopetzky syndrome (Obscure Auditory Dysfunction, OAD) has been recognized as a clinically distinct condition in audiological and ENT clinics. It is characterized by normal hearing thresholds on pure tone audiometry (PTA) but complaints of difficulties in understanding speech in the presence of background noise. In a study on 110 consecutive patients with King-Kopezky syndrome referred to the Welsh Hearing Institute, subjects were subdivided into seven subcategories based on sensitized measures of auditory dysfunction and on psychological assessment. These were: (1) middle ear dysfunction; (2) mild cochlear pathology; (3) central/medial olivocochlear efferent system (MOCS) auditory dysfunction; (4) purely psychological problems; (5) multiple auditory pathologies; (6) combined auditory dysfunction and psychological problems and (7) unknown. Different subgroups may represent different pathogenic and aetiological factors. Thus, subcategorization provides further understanding of the basis of King-Kopetzky syndrome, and hence may guide the rehabilitative management of these patients.

Hearing impairment may sometimes be associated with complete loss of inner hair cells (IHCs) over a certain region of the basilar membrane. We call this a 'dead region'. Amplification (using a hearing aid) over a frequency range corresponding to a dead region may not be beneficial and may even impair speech intelligibility. However, diagnosis of dead regions is not easily done from the audiogram. This paper reports the design and evaluation of a method for detecting and delimiting dead regions. A noise, called 'threshold equalizing noise' (TEN), was spectrally shaped so that, for normally hearing subjects, it would give equal masked thresholds for pure tone signals at all frequencies within the range 250-10,000 Hz. Its level is specified as the level in a one-ERB (132 Hz) wide band centred at 1000 Hz. Measurements obtained from 22 normal-hearing subjects and TEN levels of 30, 50 and 70 dB/ERB confirmed that the signal level at masked threshold was approximately equal to the noise level/ERB and was almost independent of signal frequency. Masked thresholds were measured for 20 ears of 14 subjects with sensorineural hearing loss, using TEN levels of 30, 50 and 70 dB/ERB. Psychophysical tuning curves (PTCs) were measured for the same subjects. When there are surviving IHCs corresponding to a frequency region with elevated absolute thresholds, a signal in that frequency region is detected via IHCs with characteristic frequencies (CFs) close to that region. In such a case, threshold in the TEN is close to that for normal-hearing listeners, provided that the noise intensity is sufficient to produce significant masking. Also, the tip of the PTC lies close to the signal frequency. When a dead region is present, the signal is detected via IHCs with CFs different from that of the signal frequency. In such a case, threshold in the TEN is markedly higher than normal, and the tip of the PTC is shifted away from the signal frequency. Generally, there was a very good correspondence between the results obtained using the TEN and the PTCs. We conclude that the measurement of masked thresholds in TEN provides a quick and simple method for the diagnosis of dead regions.

Surprisingly little evidence is available in children between the ages of 3 and 7 years on the effect on hearing thresholds of the method of audiometry and of the developmental ability to concentrate and to respond. The Trial of Alternative Regimens in Glue Ear Treatment (TARGET) is a large, national, multi-centre trial of surgical intervention in children with otitis media with effusion (OME) that offers an opportunity to study these effects. Of 1517 children, aged between 3.25 and 6.75 years, reaching the selection stage, 4.5% were unable to give reliable air-conduction thresholds. A further 3% (i.e. 7.5% in all) could not give reliable bone-conduction thresholds. This inability was greatest in the youngest children. During air-conduction testing, a significantly greater proportion (p <0.005) of children were recorded as having only 'fair' or 'poor' concentration on conventional audiometry than with play audiometry. On the other hand, the magnitude of the effect of poor concentration, as rated 'fair/poor' versus 'good', was slightly greater on play as opposed to conventional audiometry (+5 dB versus +3 dB). Although statistically significant, the age of the child had only a very small effect on the air- or bone-conduction thresholds, once the type of audiometry, concentration and the presence of OME had been controlled for. It is concluded that adequately informative thresholds are usually obtainable by conventional audiometry in this age group, even if the concentration is recorded as 'fair' or 'poor'. However, when conventional audiometry is not feasible, play audiometry should be attempted in the 3-5-year-old age group.

The aim of this study was to explore the relationship between approach to communication, speech perception and speech intelligibility after cochlear implantation of young children with profound early deafness. A prospective speech perception and speech intelligibility assessment was undertaken on a consecutive group of implanted children. There were 46 children at the three-year, 26 at the four-year and 20 at the five-year intervals. All had been born deaf or deafened before the age of three and received cochlear implants before the age of seven. Their speech perception ability and the intelligibility of their speech were measured before cochlear implantation and annually thereafter. The children's communication had been classified by their teachers of the deaf at each interval into one of two categories: those using an oral approach and those using a signing approach. Results revealed that at all intervals, those children classified as using oral communication significantly exceeded those using signed communication on measures of speech perception and intelligibility (p<0.05). When those children who had changed from signed to oral communication were compared at the three-year interval with those who used oral communication throughout, there was no significant difference in their results. However, it remains to be explored whether children use oral communication after cochlear implantation because they are doing well, or whether they do well because they are using oral communication.