ABSTRACT
To further develop a multiple stimulus method for the rapid acquisition of auditory brainstem responses (ABRs), a 56-stimulus train was tested in mice. Stimuli in the train were tone bursts spaced at 0.5-octave intervals from 4 to 32 kHz. ABR thresholds, latency-intensity and amplitude-intensity functions were obtained using stimuli presented singly (one at a time) and using the 56-stimulus train. Responses from stimuli presented singly and those obtained using the 56-stimulus train were compared. There were no significant differences in thresholds (0.01 level) and very small differences in response latencies and amplitudes. These findings demonstrate the feasibility of multiple stimulus trains for the rapid acquisition of ABRs.
Subject(s)
Brain/physiology , Evoked Potentials, Auditory, Brain Stem , Animals , Female , Mice , Mice, Inbred C3HABSTRACT
A study by Penner (J Speech Hear Res 1980;23:779-86) found evidence for impaired lateral suppression in subjects with tinnitus and sensorineural hearing loss. If lateral suppression is related to tuning curve sharpness and lateral suppression is impaired, the shape of the tuning curve should be affected. The purpose of this study was to determine whether subjects with tinnitus have psychophysical tuning curves that are different from those of subjects without tinnitus. Psychophysical tuning curves and hearing thresholds were obtained from 18 subjects, 7 with tinnitus and 11 without tinnitus. Only subjects with normal audiograms (through 8 kHz) were selected for this study. In subjects with tinnitus psychophysical tuning curves were obtained in the region pitch-matched to their tinnitus. In nontinnitus subjects psychophysical tuning curves were determined at the same frequencies as for the tinnitus subjects in a yoked-control design. The slopes of the tails and tips and the Q10 and other measures were calculated for each tuning curve. The psychophysical tuning curves in subjects with tinnitus were significantly different (0.01 level) from those of control subjects and often had hypersensitive tails and some elevated tips. These shapes of tuning curves are consistent with cochlear lesions involving the loss of outer hair cells without damage to the inner hair cells or nerve fibers.
Subject(s)
Hair Cells, Auditory/physiopathology , Psychoacoustics , Tinnitus/diagnosis , Vestibular Function Tests , Adolescent , Adult , Audiometry, Pure-Tone , Auditory Threshold , Female , Hearing/physiology , Hearing Loss, Sensorineural/diagnosis , Hearing Loss, Sensorineural/physiopathology , Hearing Tests , Humans , Male , Middle Aged , Perceptual Masking , Tinnitus/complications , Tinnitus/physiopathologyABSTRACT
Improved procedures have been developed for obtaining hearing thresholds, loudness matches, pitch matches, and masking curves of tinnitus. Computer programs enable all of these measures to be obtained in a single session. These measures have been obtained in tinnitus and nontinnitus subjects, with an external stimulus used to simulate tinnitus in nontinnitus subjects. These measures, obtained in repeated sessions, were used to determine the test-retest variability of each measure. The test-retest standard error of measurement, across-subjects, is reported, which enables changes in tinnitus to be determined. In nontinnitus subjects, the accuracy, as well as the reliability, is described.
