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Although the ferret has become an important model species for studying both fundamental and clinical aspects of spatial hearing, previous behavioral work has focused on studies of sound localization and spatial release from masking in the free field. This makes it difficult to tease apart the role played by different spatial cues. In humans and other species, interaural time differences (ITDs) and interaural level differences (ILDs) play a critical role in sound localization in the azimuthal plane and also facilitate sound source separation in noisy environments. In this study, we used a range of broadband noise stimuli presented via customized earphones to measure ITD and ILD sensitivity in the ferret. Our behavioral data show that ferrets are extremely sensitive to changes in either binaural cue, with levels of performance approximating that found in humans. The measured thresholds were relatively stable despite extensive and prolonged (>16 weeks) testing on ITD and ILD tasks with broadband stimuli. For both cues, sensitivity was reduced at shorter durations. In addition, subtle effects of changing the stimulus envelope were observed on ITD, but not ILD, thresholds. Sensitivity to these cues also differed in other ways. Whereas ILD sensitivity was unaffected by changes in average binaural level or interaural correlation, the same manipulations produced much larger effects on ITD sensitivity, with thresholds declining when either of these parameters was reduced. The binaural sensitivity measured in this study can largely account for the ability of ferrets to localize broadband stimuli in the azimuthal plane. Our results are also broadly consistent with data from humans and confirm the ferret as an excellent experimental model for studying spatial hearing.

161 patients have been offered assessment and patient uptake is high with only 23 (14%) declining assessment. 52 (32%) patients were offered group therapy and the rest received individual therapy or declined ongoing support. Patients have been keen to access the service and feedback from those who have accessed it has been positive. Conclusions There is high demand for an IBD psychology service with high patient uptake. This has led to pressure on the service and development of a long waiting list.Within the IBD team there is improved understanding of what psychology can offer but the wide variation in referrals between individuals would suggest that further education as to the role of psychological input is required. This is supported by the observation that the greatest numbers of referrals come from sources where psychologist has most interaction.As referrals increase the service will have to adapt to manage them as a 5 month waiting list is inappropriate for certain referrals.Provision of this service has allowed the team to move closer to meeting IBD standards (IBDUK, 2019).

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