Speech-in-noise testing as a marker for noise-induced hearing loss and tinnitus.

Speech-in-noise testing as a marker for noise-induced hearing loss and tinnitus. Noise-induced hearing loss and tinnitus are auditory complaints that often co-occur. Often, there is no immediate indication of changes in the pure tone audiogram. Patients can still have clinically normal hearing thresholds while clearly experiencing reduced speech comprehension. This might be explained by the process of neurodegeneration of the innervated dendrites of the auditory nerve fibres and secondary degeneration of spiral ganglion neurons. Subsequent maladaptive neuronal plasticity of the central auditory system can induce tinnitus. Standard hearing testing is no longer sufficient in these patients. Therefore more complex tasks, such as speech-in-noise tests, might be valuable extensions to the standard hearing tests. We carried out a prospective investigation of the influence of tinnitus upon speech comprehension in noise and the effectiveness of speech-in-noise testing, using the Flemish version of the digit triplet test (DTT). Thirty-seven patients with mild noise-induced hearing loss, tinnitus complaints and clinically normal pure tone thresholds completed the DTT and filled in two tinnitus enquiries. A statistically significant (p=0.026) correlation between the averaged high PTA, 2,z and the averaged SRT across ears on the DTT was found. There also seems to be a slight influence of tinnitus onset on the SRT score.

Auditory neuropathy/dyssynchrony revisited.

Auditory neuropathy/dyssynchrony (AN/AD) is a relatively, recently described diagnostic term. It describes a disorder characterised by detectable otoacoustic emissions and/or cochlear microphonics, combined with abnormal or absent auditory brainstem responses and deficient speech understanding. Consequently, the patient's cognitive responses are inconsistent with a behavioural tone audiogram. This review describes the epidemiology, pathogenesis, diagnosis, and treatment of AN/AD. We have focused on the diagnostic pathway, because diagnosis is sometimes difficult, and recent research has provided important insights into the aetiopathology of the disease. The diagnostic tools for AN/AD currently used in our department will be demonstrated in a clinical case. It is very important to recognise AN/AD and provide patient counselling and support as early as possible, due to the potentially major influence of this disorder on a patient's social life and language acquisition.