The impact of measurement goals on the design specification for outcome measures.

No outcome measure has universal validity and applicability. When designing, promulgating or selecting a particular instrument, audiologists should take care to consider and specify the detailed purposes to which the measure will be directed, and the particular populations to which it will be applied. Scales that have been optimized in one arena will have limited (though perhaps still useful) generalizability. The importance dimensions of difference between applications are numerous.

Optimal outcome measures, research priorities, and international cooperation.

The participants in the Eriksholm Workshop on "Measuring Outcomes in Audiological Rehabilitation Using Hearing Aids" debated three issues that are reported in this article. First, it was agreed that the characteristics of an optimal outcome measure vary as a function of the purpose of the measurement. Potential characteristics of outcome self-report tools for four common goals of outcome measurement are briefly presented to illustrate this point. Second, 10 important research priorities in outcome measurement were identified and ranked. They are presented with brief discussion of the top five. Third, the concept of generating a brief universally applicable outcome measure was endorsed. This brief data set is intended to supplement existing outcome measures and to promote data combination and comparison across different social, cultural, and health-care delivery systems. A set of seven core items is proposed for further study.

Sound localization in noise in hearing-impaired listeners.

The present study assesses the ability of four listeners with high-frequency, bilateral symmetrical sensorineural hearing loss to localize and detect a broadband click train in the frontal-horizontal plane, in quiet and in the presence of a white noise. The speaker array and stimuli are identical to those described by Lorenzi et al. (in press). The results show that: (1) localization performance is only slightly poorer in hearing-impaired listeners than in normal-hearing listeners when noise is at 0 deg azimuth, (2) localization performance begins to decrease at higher signal-to-noise ratios for hearing-impaired listeners than for normal-hearing listeners when noise is at +/- 90 deg azimuth, and (3) the performance of hearing-impaired listeners is less consistent when noise is at +/- 90 deg azimuth than at 0 deg azimuth. The effects of a high-frequency hearing loss were also studied by measuring the ability of normal-hearing listeners to localize the low-pass filtered version of the clicks. The data reproduce the effects of noise on three out of the four hearing-impaired listeners when noise is at 0 deg azimuth. They reproduce the effects of noise on only two out of the four hearing-impaired listeners when noise is at +/- 90 deg azimuth. The additional effects of a low-frequency hearing loss were investigated by attenuating the low-pass filtered clicks and the noise by 20 dB. The results show that attenuation does not strongly affect localization accuracy for normal-hearing listeners. Measurements of the clicks' detectability indicate that the hearing-impaired listeners who show the poorest localization accuracy also show the poorest ability to detect the clicks. The inaudibility of high frequencies, "distortions," and reduced detectability of the signal are assumed to have caused the poorer-than-normal localization accuracy for hearing-impaired listeners.

Sound localization in noise in normal-hearing listeners.

The ability to localize a click train in the frontal-horizontal plane was measured in quiet and in the presence of a white-noise masker. The experiment tested the effects of signal frequency, signal-to-noise ratio (S/N), and masker location. Clicks were low-pass filtered at 11 kHz in the broadband condition, low-pass filtered at 1.6 kHz in the low-pass condition, and bandpass filtered between 1.6 and 11 kHz in the high-pass condition. The masker was presented at either -90, 0, or +90 deg azimuth. Six signal-to-noise ratios were used, ranging from -9 to +18 dB. Results obtained with four normal-hearing listeners show that (1) for all masker locations and filtering conditions, localization accuracy remains unaffected by noise until 0-6 dB S/N and decreases at more adverse signal-to-noise ratios, (2) for all filtering conditions and at low signal-to-noise ratios, the effect of noise is greater when noise is presented at +/- 90 deg azimuth than at 0 deg azimuth, (3) the effect of noise is similar for all filtering conditions when noise is presented at 0 deg azimuth, and (4) when noise is presented at +/- 90 deg azimuth, the effect of noise is similar for the broadband and high-pass conditions, but greater for the low-pass condition. These results suggest that the low- and high-frequency cues used to localize sounds are equally affected when noise is presented at 0 deg azimuth. However, low-frequency cues are less resistant to noise than high-frequency cues when noise is presented at +/- 90 deg azimuth. When both low- and high-frequency cues are available, listeners base their decision on the cues providing the most accurate estimation of the direction of the sound source (high-frequency cues). Parallel measures of click detectability suggest that the poorer localization accuracy observed when noise is at +/- 90 deg azimuth may be caused by a reduction in the detectability of the signal at the ear ipsilateral to the noise.

A self-report outcome measure for the evaluation of hearing aid fittings and services.

OBJECTIVE: To design, optimise and validate an outcome measure for the evaluation of adult hearing aid fittings. DESIGN: A multi-dimensional subject-specific and situation-specific questionnaire (the Glasgow Hearing Aid Benefit Profile--GHABP) to assess initial disability, handicap, use, benefit, residual disability and satisfaction before and after hearing aid provision. SUBJECTS: Hearing-impaired adults attending National Health Service clinics for the first time for whom amplification is an appropriate management option. RESULTS: A self-report instrument of length compatible with the requirements of routine clinical practice which retains psychometric leverage. The GHABP demonstrates sensitivity to the technological content and rehabilitative context of interventions. The scale properties facilitate the use of the GHABP in decision-making for individual hearing-impaired patients. CONCLUSION: An outcome measure such as the GHABP offers the various interested parties (purchasers, providers and patients) a tool for use in the evaluation of the effectiveness and cost effectiveness of existing services and future developments. Many of the design concepts embodied in the GHABP are applicable in other healthcare contexts.

Speech tests as measures of outcome.

Speech tests comprise an important and integral part of any assessment of the effectiveness of intervention for hearing disability and handicap. Particularly when considering hearing aid services for adult listeners, careful consideration has to be given to the particular form and application of inferences drawn from speech identification procedures if erroneous conclusions are to be avoided. It is argued that four such components relate to the statistical properties and discriminatory leverage of speech identification procedures, the choice of presentation level and conditions in regard to the auditory environment experienced by hearing-impaired clients, the extent to which speech tests based on segmental intelligibility provide appropriate information in relationship to perceived disabilities and handicaps, and the ways in which speech identification procedures to evaluate the potential benefits of signal-processing schemes for hearing aids are dependent upon sufficient listening experiences. Data are drawn from the literature to illuminate these points in terms of application in clinical practice and clinical evaluation exercises, and also with regard to future research needs.

Problems in assessing the audiogram in patients with severe hearing impairment.

Severe hearing impairment (SHI) is an impairment of hearing in which the air conduction mean over 0.5-4 kHz in the better hearing ear lies between 70 and 90 dB. Masking of bone and air conduction thresholds is seldom possible with SHI, leading to difficulties in assessing the pure tone audiogram whenever there is a potential air bone gap in either ear. An audiological survey of 83 patients with severe hearing impairment was conducted. In 16 per cent of patients there was no possibility of a material air bone gap in either ear and no difficulty in interpreting the audiogram. In 23 (28 per cent), the audiogram was consistent with, but did not prove the presence of, an air bone gap in the poorer hearing ear. In 25 patients (30 per cent of 108) the better hearing ear could not be determined, and in 22 (27 per cent) a profound sensorineural impairment in the poorer hearing ear could not be excluded. The implications of this for the otologist are discussed.

Report of the Eriksholm Workshop on auditory deprivation and acclimatization.

The terminology used in studies documenting changes in auditory performance following fitting of hearing aids has been diverse. Definitions for the auditory deprivation effect and auditory acclimatization are offered as a first step in rationalization. Two statements summarize current knowledge concerning auditory deprivation effects and auditory acclimatization, as well as considering the potential implications for research, field trial and clinical practice applications. Potential areas for future research are identified.

Measuring patient benefit from otorhinolaryngological surgery and therapy.

The Glasgow Benefit Inventory (GBI) is a measure of patient benefit developed especially for otorhinolaryngological (ORL) interventions. Patient benefit is the change in health status resulting from health care intervention. The GBI was developed to be patient-oriented, to be maximally sensitive to ORL interventions, and to provide a common metric to compare benefit across different interventions. The GBI is an 18-item, postintervention questionnaire intended to be given to patients to fill in at home or in the outpatient clinic. In the first part of the paper, five different ORL interventions were retrospectively studied: middle ear surgery to improve hearing, provision of a cochlear implant, middle ear surgery to eradicate ear activity, rhinoplasty, and tonsillectomy. A criterion that was specific to the intervention was selected for each study, so that the patient outcome could be classified as above and below criterion. In all five interventions, the GBI was found to discriminate between above- and below-criterion outcomes. The second part of the paper reports on the results and implications of a factor analysis of patient responses. The factor structure was robust across the study, and so led to the construction of subscales. These subscales yield a profile score that provides information on the different types of patient benefit resulting from ORL interventions. The GBI is sensitive to the different ORL interventions, yet is sufficiently general to enable comparison between each pair of interventions. It provides a profile score, which enables further breakdown of results. As it provides a patient-oriented common metric, it is anticipated that the GBI will assist audit, research, and health policy planning.

Test-retest reliability of loudness scaling.

OBJECTIVE: Establish the test-retest reliability of loudness scaling using a bounded category rating method. DESIGN: The individual loudness functions were investigated in three groups of listeners: seven normal-hearing listeners age 18 to 35 yr, five normal-hearing listeners aged 57 to 84 yr, and five listeners aged 54 to 82 yr with bilateral sloping sensorineural hearing loss. Test-retest reliability was investigated by determining the intralistener, between-session standard deviation. RESULTS: The pattern of test-retest reliability was similar across all three groups. It improved as the intensity of the stimulus increased: 7 dB at the first quartile of the loudness function, and 3 dB at the third quartile. Two to four runs of the task appear to be sufficient to obtain a stable loudness function, and it was shown that an exponential function provided a better goodness of fit than a linear function (r2: 0.99 compared with 0.94). CONCLUSIONS: Loudness scaling is a longer test than most conventional suprathreshold measures and requires special equipment. However, it has good test-retest reliability and provides more information on the loudness function that might be useful in the fitting of nonlinear hearing aids. The data show that an exponential function provides a good fit to the loudness growth data, and should probably be incorporated into fitting algorithms associated with loudness scaling.

The value of routine in-the-ear measurement of hearing aid gain.

When selecting the frequency response of a hearing aid, a target is usually selected using a predictive formula from the international literature. Nowadays real ear measurements can readily be carried out to ensure that the real ear gain closely matches the prescribed target. Such measurements are usually only carried out on a subset of patients fitted in the UK, though it has been suggested that they should be carried out on all hearing aid prescriptions. Real ear insertion gains were measured on 319 first-time National Health Service (NHS) hearing aid issues. A total of 181 (57%) failed to come within 10 dB of the target gain at one or more frequencies between 0.25 and 3 kHz. Though there were audiometric differences between those who achieved satisfactory gain and those who did not, there was too much overlap between groups to make any audiometric index or combination of indices of value in predicting the likelihood of failure to achieve target gain. Sixty-eight patients with inadequate real ear gain were invited to attend for alterations to their hearing aid prescription. Twelve (18%) were fitted with a high frequency aid, while the rest were managed by alterations to their NHS aid or to the earmould and tubing. After appropriate changes, 58 (85%) achieved a satisfactory gain. The routine use of real ear insertion gains in all hearing aid fittings would result in many patients having a more accurately fitted hearing aid. As the majority of prescriptions could be adequately improved using NHS hearing aids, the effects on the hearing aid budget would be relatively small.

The effect of recurrent tonsillitis and tonsillectomy on growth in childhood.

The aim of this study was to determine if children with recurrent tonsillitis are smaller than expected before tonsillectomy and if they have an altered height or weight gain 1 year post-operatively. All (204) children attending the hospital for tonsillectomy with or without adenoidectomy had their height and weight measured pre-operatively and 1 year after operation. The results of 2204 children in local schools were used as a control population. Analysis was by comparison of each population with the Tanner charts. This study suggests that our population of children listed for tonsillectomy were not lighter or smaller than expected before operation but that one year after tonsillectomy, there was an increase in their weight gain. The height gain was no different than expected after operation. Overweight seems to be a medium term complication of tonsillectomy. It may be necessary to redefine the indications for tonsillectomy in children who are already obese.

Idiopathic epistaxis, haemostasis and alcohol.

Recent studies have suggested a link between antiplatelet medications and alcohol in the aetiology of acute adult epistaxis. The possibility that adult epistaxis may be associated with alcohol induced platelet dysfunction has not previously been investigated. This study evaluated primary haemostasis in 50 adult patients with idiopathic epistaxis. A detailed alcohol history was recorded and the Simplate bleeding time device was used to test haemostatic function. Forty-six per cent of patients were found to have an abnormality of primary haemostasis. Prolongation of the bleeding time was significantly associated with a history of alcohol use. The effect of alcohol on the bleeding time duration was significant (P < 0.001) even at low levels of intake of between 1 and 10 units per week. Although prevalent in the study group (42%) the use of non-steroidal anti-inflammatory drugs did not confer a significant additional risk of increased bleeding time. These findings support the importance of alcohol induced haemostatic abnormalities in the aetiology of adult epistaxis.

Changes in intensity discrimination following monaural long-term use of a hearing aid.

Previous work has shown that a normally aided ear tested without the hearing aid is better able to identify speech-in-noise than the unaided ear at high sound levels, while performance for the unaided ear is superior at lower sound levels [S. Gatehouse, J. Acoust. Soc. Am. 86, 2103-6 (1989); J. Acoust. Soc. Am. 92, 1258-68 (1992)]. This effect was further explored using intensity discrimination for complex stimuli. Stimuli were half-octave bandpass-filtered tone complexes centered at 0.25 and 3 kHz. Four bilateral, symmetric hearing-impaired listeners with mean HL of 24 dB at 0.25 kHz, and 58 dB at 3 kHz were tested. Intensity discrimination was performed across the dynamic range of the listeners. At sound-pressure levels greater than 85 dB, the normally aided ear tested without the aid was more sensitive to changes in intensity than the unaided ear, whereas at lower levels, the converse occurred. This pattern was observed only for the 3-kHz center frequency, and not for the 0.25-kHz center frequency. Insertion gain measurements using the aids at normal volume showed an average of 20 dB gain at 3 kHz, and -2 dB gain at 0.25 kHz. The changes in intensity discrimination in the normally aided ear are consistent with the frequency-gain characteristics of the hearing aid, and suggest that a change in intensity coding occurred.