The relationship between tinnitus pitch and parameters of audiometry and distortion product otoacoustic emissions.

OBJECTIVES: Chronic tinnitus is associated with reduced auditory input, which results in changes in the central auditory system. This study aimed to examine the relationship between tinnitus pitch and parameters of audiometry and distortion product otoacoustic emissions. For audiometry, the parameters represented the edge frequency of hearing loss, the frequency of maximum hearing loss and the frequency range of hearing loss. For distortion product otoacoustic emissions, the parameters were the frequency of lowest distortion product otoacoustic emission amplitudes and the frequency range of reduced distortion product otoacoustic emissions. METHOD: Sixty-seven patients (45 males, 22 females) with subjective chronic tinnitus, aged 18 to 73 years, were included. RESULTS: No correlation was found between tinnitus pitch and parameters of audiometry and distortion product otoacoustic emissions. However, tinnitus pitch fell mostly within the frequency range of hearing loss. CONCLUSION: The current study seems to confirm the relationship between tinnitus pitch and the frequency range of hearing loss, thus supporting the homeostatic plasticity model.

The impact of tinnitus characteristics and associated variables on tinnitus-related handicap.

OBJECTIVE: This study aimed to determine the characteristics of tinnitus and tinnitus-related variables and explore their possible relationship with tinnitus-related handicap. METHODS: Eighty-one patients with chronic tinnitus were included. The study protocol measured hearing status, tinnitus pitch, loudness, maskability and loudness discomfort levels. All patients filled in the Tinnitus Sample Case History Questionnaire, the Hyperacusis Questionnaire and the Tinnitus Handicap Inventory. The relationship of each variable with the Tinnitus Handicap Inventory score was evaluated by univariate and multivariate analyses. RESULTS: Five univariables were associated with the Tinnitus Handicap Inventory score: loudness discomfort level, subjective tinnitus loudness, tinnitus awareness, noise intolerance and Hyperacusis Questionnaire score. Multiple regression analysis showed that the Hyperacusis Questionnaire score and tinnitus awareness were independently associated with the Tinnitus Handicap Inventory score. CONCLUSION: Hyperacusis and tinnitus awareness were independently associated with the Tinnitus Handicap Inventory score. Questionnaires on tinnitus and hyperacusis are especially suited to providing additional insight into tinnitus-related handicap and are therefore useful for evaluating tinnitus patients.

Olivocochlear efferent reflex strength in vestibular schwannoma patients.

PROBLEM/OBJECTIVE: The olivocochlear reflex strength can be measured using contralateral acoustic stimulation (CAS) of transient evoked otoacoustic emissions (TEAOEs). The efferent suppression (ES) thus reflects the functional intactness of the efferent auditory system. In patients with unilateral vestibular schwannoma (VS), the results of ES are unclear. METHODS: This cross-sectional study evaluated click and noise intensity conditions for measuring ES using CAS of TEOAEs in nine patients with unilateral VS and in gender-, age- and ear side-matched control subjects. RESULTS: Two optimal click and noise intensity level combinations were identified. This pilot study compared the amount of ES between tumour and non-tumour ears versus control ears in patients with unilateral VS, but there were no statistically significant differences. CONCLUSION: Future studies should include a larger population of unilateral VS patients with different grades of hearing loss.

Experimental evidence for the source of excess sulfur in explosive volcanic eruptions

The amounts of sulfur released in explosive volcanic eruptions are often orders of magnitude larger than those expected to result from the degassing of the erupted SiO2-rich magma. Experimentally measured fluid/melt partition coefficients of sulfur ranged from 47 under oxidizing conditions (where SO2 is the dominant sulfur species in the fluid) to 468 under reducing conditions (where H2S dominates). Therefore, a few weight percent of hydrous fluid accumulated in the top of a magma chamber may extract most of the sulfur out of the entire magma reservoir and generate sulfur excesses upon eruption.