The mechanical frequency selectivity of the cupula located in the supraorbital lateral line canal and the frequency selectivity of the hair cells driven by the cupula were measured simultaneously in vivo. Laser interferometry was used to measure cupular mechanics and extracellular receptor potentials were recorded to determine hair cell frequency selectivity. Results were obtained from two teleost fish species, the ruffe (Acerina cernua L.), a European temperate zone freshwater fish, and the tropical African knife fish (Xenomiystus nigri). In both species cupular displacement grows with increasing frequency of canal fluid displacement, reaching a maximum at 115 Hz in the ruffe and at 460 Hz in the African knife fish. Cupular best frequencies were independent of temperature. Cut-off frequencies of hair cell frequency selectivity were found to depend on temperature with a Q10 of 1.75, ranging from 116 Hz (4 degrees C) to 290 Hz (20 degrees C), as established in the ruffe. At normal habitat temperatures of the two fish species (ruffe, 4 degrees C; African knife fish, 28 degrees C), this results in hair cell cut-off frequencies that match the two different cupular best frequencies remarkably well. This match suggests adjusted signal transfer in these two peripheral stages of canal lateral line transduction.

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Objective: Investigate the association between age-related hearing loss and reduced peripheral vestibular function using paired assessments of high-frequency hearing and horizontal semicircular canal (HSC) function. We hypothesized that age-related high-frequency hearing loss would be correlated with reduced HSC function and, therefore, useful to predict age-related vestibular hypofunction. Design:We conducted a single center, retrospective cross-sectional study in a tertiary/academic referral hospital. This study included 185 patients who were diagnosed with a cerebellopontine angle (CPA) tumor and referred to the academic hospital to evaluate treatment options. Data collected included pure-tone audiometry, caloric reflex test, video headimpulse test (vHIT), and medical history. High-frequency hearing loss was quantified by the high Fletcher index (hFI), and horizontal semicircular canal (HSC) function were quantified by the caloric reflex test and vHIT. Results:We observed a significant association between age and highfrequency hearing loss that was significantly worse in men compared with women. In contrast, we observed no significant association between age and HSC function assessed by either the caloric reflex test or vHIT. We observed associations between HSC function and sex, with male sex predicting reduced HSC function by caloric reflex testing but enhanced HSC function by vHIT. High-frequency hearing loss did not predict HSC hypofunction. Conclusions:We found no evidence indicating age-related decline in HSC function or an association between age-related high-frequency hearing loss and age-related decline in HSC function. We did observe sex-specific differences in HSC function. Our study highlights the need for sex-specific normative values for identifying age-related reduced peripheral vestibular function and for future work linking comprehensive assessments of inner ear function with tests of balance and stability to understand the complex interactions underlying hearing loss and imbalance, especially in the elderly.

In a two-alternative, forced-choice experiment, subjects had to compare the pitches of two sounds, A and B. Each sound was composed of four successive harmonics of a fundamental frequency between 100 to 250 Hz, added in cosine or Schröder phase. The harmonic frequencies of A were lower than those of B; the missing fundamental frequency of A was higher than that of B. The dominance of the missing fundamental versus the spectrally cued pitch--a pitch percept corresponding to spectral components--was measured as a function of nA, the lowest harmonic in A. The pitch percept is dominated by the missing fundamental if the harmonics are resolved (nA<7). If the harmonics become unresolved and are added in Schröder phase, the dominance shifts to a spectrally cued pitch (720). For others, the transition was in the realm of partly resolved harmonics. This shows that the temporal envelope modulation of stimuli with only four unresolved harmonics can give a relatively clear fundamental pitch percept. However, this percept varies considerably among subjects.