Abstract:A 22-year-old woman consumed approximately 10 g of salicylate with suicidal intent. She had a severe hearing loss and a strong tinnitus within 22 h of the overdose, and then 24 h later a subsequent hearing restoration and tinnitus abolishment. Transiently evoked otoacoustic emissions ͑TEOAEs͒ and 2 f 1Ϫ f 2 distortion product otoacoustic emissions ͑DPOAEs͒ were measured in both states. In the state of intoxication DPOAEs could be recorded well in the frequency range that corresponded to the appearance of the t… Show more
“…However, with OHC damage, the BM response at CF exhibits an elevated threshold, reduced compression, and a steeper slope of the I/O function. Similar findings were reported for DPOAE I/O functions following cochlear insults in animals ͑Norton and Rubel, 1990;Whitehead et al, 1992;Mills et al, 1993;Rubel, 1994͒ andin cochlear impaired human ears ͑Janssen et al, 1998;Kummer et al, 1998;Janssen et al, 2000;Dorn et al, 2001͒. However, the degree to which DPOAE level dependence reflects BM level dependence at CF remains to be established.…”
Given that high-frequency hearing is most vulnerable to cochlear pathology, it is important to characterize distortion-product otoacoustic emissions (DPOAEs) measured with higher-frequency stimuli in order to utilize these measures in clinical applications. The purpose of this study was to explore the dependence of DPOAE amplitude on the levels of the evoking stimuli at frequencies greater than 8 kHz, and make comparisons with those data that have been extensively measured with lower-frequency stimuli. To accomplish this, DPOAE amplitudes were measured at six different f2 frequencies (2, 5, 10, 12, 14, and 16 kHz), with a frequency ratio (f2/f1) of 1.2, at five fixed levels (30 to 70 dB SPL) of one primary (either f1 or f2), while the other primary was varied in level (30 to 70 dB SPL). Generally, the level separation between the two primary tones (L1 > L2) generating the largest DPOAE amplitude (referred to as the "optimal level separation") decreased as the level of the fixed primary increased. Additionally, the optimal level separation was frequency dependent, especially at the lower fixed primary tone levels ( < or = 50 dB SPL). In agreement with previous studies, the DPOAE level exhibited greater dependence on L1 than on L2.
“…However, with OHC damage, the BM response at CF exhibits an elevated threshold, reduced compression, and a steeper slope of the I/O function. Similar findings were reported for DPOAE I/O functions following cochlear insults in animals ͑Norton and Rubel, 1990;Whitehead et al, 1992;Mills et al, 1993;Rubel, 1994͒ andin cochlear impaired human ears ͑Janssen et al, 1998;Kummer et al, 1998;Janssen et al, 2000;Dorn et al, 2001͒. However, the degree to which DPOAE level dependence reflects BM level dependence at CF remains to be established.…”
Given that high-frequency hearing is most vulnerable to cochlear pathology, it is important to characterize distortion-product otoacoustic emissions (DPOAEs) measured with higher-frequency stimuli in order to utilize these measures in clinical applications. The purpose of this study was to explore the dependence of DPOAE amplitude on the levels of the evoking stimuli at frequencies greater than 8 kHz, and make comparisons with those data that have been extensively measured with lower-frequency stimuli. To accomplish this, DPOAE amplitudes were measured at six different f2 frequencies (2, 5, 10, 12, 14, and 16 kHz), with a frequency ratio (f2/f1) of 1.2, at five fixed levels (30 to 70 dB SPL) of one primary (either f1 or f2), while the other primary was varied in level (30 to 70 dB SPL). Generally, the level separation between the two primary tones (L1 > L2) generating the largest DPOAE amplitude (referred to as the "optimal level separation") decreased as the level of the fixed primary increased. Additionally, the optimal level separation was frequency dependent, especially at the lower fixed primary tone levels ( < or = 50 dB SPL). In agreement with previous studies, the DPOAE level exhibited greater dependence on L1 than on L2.
“…The significant increase of optimum frequency ratios during anaesthesia could be caused by endocochlear potential related deterioration of mechanical cochlear frequency tuning (Ruggero and Rich 1991) as a consequence of reduction of cochlear amplifier action. The fact that the slopes of cubic DPOAE growth functions increased strongly during anaesthesia is comparable to a steepening of DPOAE growth functions in patients with cochlear hearing loss or tinnitus (Janssen et al 1998(Janssen et al , 2000(Janssen et al , 2006. Indeed, the slopes can be used as indicator of changes in cochlear function (Neely et al 2003;Müller and Janssen 2004).…”
Section: General Impact On Cochlear Physiologymentioning
confidence: 85%
“…Brown and Kemp 1984;Gaskill and Brown 1990;Probst et al 1991;Brown et al 1992;Janssen et al 2000;Shera et al 2002;Boege and Janssen 2002). They provide a fast and efficient assessment of mechanical threshold sensitivity in different vertebrates and even in insects (e.g.…”
Ketamine is a dissociative anaesthetic, analgesic drug as well as an N-methyl-D-aspartate receptor antagonist and has been reported to influence otoacoustic emission amplitudes. In the present study, we assess the effect of ketamine-xylazine on high-frequency distortion-product otoacoustic emissions (DPOAE) in the bat species Carollia perspicillata, which serves as model for sensitive high-frequency hearing. Cubic DPOAE provide information about the nonlinear gain of the cochlear amplifier, whereas quadratic DPOAE are used to assess the symmetry of cochlear amplification and potential efferent influence on the operating state of the cochlear amplifier. During anaesthesia, maximum cubic DPOAE levels can increase by up to 35 dB within a medium stimulus level range from 35 to 60 dB SPL. Close to the -10 dB SPL threshold, at stimulus levels below about 20-30 dB SPL, anaesthesia reduces cubic DPOAE amplitudes and raises cubic DPOAE thresholds. This makes DPOAE growth functions steeper. Additionally, ketamine increases the optimum stimulus frequency ratio which is indicative of a reduction of cochlear tuning sharpness. The effect of ketamine on cubic DPOAE thresholds becomes stronger at higher stimulus frequencies and is highly significant for f2 frequencies above 40 kHz. Quadratic DPOAE levels are increased by up to 25 dB by ketamine at medium stimulus levels. In contrast to cubic DPOAEs, quadratic DPOAE threshold changes are variable and there is no significant loss of sensitivity during anaesthesia. We discuss that ketamine effects could be caused by modulation of middle ear function or a release from ipsilateral efferent modulation that mainly affects the gain of cochlear amplification.
“…However, the data do not indicate, either for amplitude or time course, clear correlations between the reduction and/or disappearance of spontaneous OAE and the loss of absolute hearing sensitivity. Studies of evoked OAE (Long and Tubis, 1988b;Janssen et al, 2000) indicate reductions in response amplitude and associated threshold elevation, corresponding with loss of absolute hearing sensitivity. The reductions in the distortion product otoacoustic emission (DPOAE) amplitude become more pronounced as the levels of the stimuli are lowered (Kujawa et al, 1992;Fitzgerald et al, 1993).…”
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