About 5% of those presenting at an ENT clinic with ear or hearing complaints are found to have normal pure-tone thresholds. Many of this group complain specifically of difficulties understanding speech in background noise. We have termed this complaint 'Obscure Auditory Dysfunction' (OAD). Previous research on OAD (Saunders and Haggard, 1992) on a sample of 50 patients and 50 matched controls showed that 83% of the deviance (binary variance) in membership of group (OAD/control) could be explained by four variables, with three underlying factors. These four variables are performance threshold in noise for speech; discrepancy between this and a self-adjusted signal-to-noise ratio value (i.e. a measure of auditory confidence); dichotic listening performance; and performance on a psychoacoustic test, the threshold for detecting a tone in a spectrally notched noise. This paper reports a study on a further 59 new OAD patients and 64 unmatched controls, using the tests in the form present in the test package, plus certain others. For routine practice, slightly differing implementations of the auditory test techniques were used. Compared to the earlier sample, the new sample had poorer measures of speech reception threshold in noise and they considered themselves more handicapped by their OAD state; however there was no significant difference between the two samples on the other performance variables. Overall, the results demonstrate the robustness of the conclusions reached from the previous study, as the test-variable determinants of OAD status (i.e. case-control differences) were similar. The items on the OAD interview questionnaire which had shown significant differences between OADs and controls were also similar for the two OAD samples, giving a consistent picture of patient profile. These were: difficulties learning to read or write as a child (which relates to dichotic listening scores); adult ear problems; and tinnitus (which relate to the psychoacoustic scores). This necessary replication confirms the validity of the three-factor model of OAD status and the utility of the clinical test package based upon it.

(1) A four-factor reduction of simple questionnaire items well defines the domains of impact of OME, and can express the ways in which views of impact differ between teachers, ENT specialists and parents.(2) Considerable differences of perspective exist between the groups examined. (3) In valuing a set of measured outcomes on actual children, or for other policy research, sets of weights are now available to represent the differing perspectives of parents and professionals (e.g. in testing robustness of a conclusion across differing stakeholder perspectives). (4) The research and development need in respect of teachers' involvement with OME could profitably play to existing strengths. This implies the systematic and structured acquisition and evaluation of teacher-provided impact information.

The bithermal caloric test has traditionally been carried out using water but air may also be used. One of the reported disadvantages of air is the high test-retest variability (Coats et al., 1976). A recent study by Moon and Munro (1996) demonstrated that the variability could be reduced by modifying the air irrigator probe to allow greater control of probe placement and direction of air flow within the ear canal. The aim of the present study was to compare the test-retest variability of the modified air technique and the conventional water technique. Twelve normal subjects underwent four full caloric tests: twice with water and twice with air. The results show that it is possible to obtain a similar test-retest variability with the two techniques. The range for canal paresis and directional preponderance are also similar. While further research is required, the modified air technique appears to provide a reliable alternative to the traditional water technique.

The elevated ARTs in adults with histories of childhood OM result from peripheral sequelae of OM. Further evidence is required to determine any functional significance of these raised reflex thresholds.

We aimed to determine whether reported difficulties in speech understanding are associated with abnormal acoustic reflex thresholds (ARTs). The acoustic reflex has been shown to have a role in the understanding of speech at high intensities by ensuring that the strong low-frequency components of sound do not excessively mask the higher-frequency components, which are important for speech understanding. There is also wide variance in individual ARTs. Hence, the possibility arises that subjects reporting listening difficulties in noise have abnormal acoustic reflex function. In this investigation, a questionnaire to 2395 university students was used to obtain 20 subjects reporting listening difficulties in background noise and requesting advice about their hearing problems; it also screened out significant histories of middle ear disease in childhood. These subjects, and 20 control subjects reporting no listening difficulties, received a battery of performance tests and measures of acoustic reflex thresholds. Results showed significant differences in auditory performance between subjects reporting listening difficulties and those with no such difficulties, but no differences in acoustic reflex thresholds. These findings extend the relationship between reported listening difficulties and auditory performance within the "normal hearing' range, but this relationship is unlikely to be due to abnormal acoustic reflex thresholds.