No abstract available.
Acoustic Stimulation* ; Acoustics*

BACKGROUND AND OBJECTIVES: Although the suppressive effect of the medial efferent acoustic reflex is well known, the time course of this effect over prolonged periods has yet to be fully evaluated. We assessed time-dependent change in the suppression of transient evoked otoacoustic emissions (TEOAEs) by the medial efferent acoustic reflex over a relatively long period. SUBJECTS AND METHODS: We measured TEOAEs in the right ear before contralateral acoustic stimulation (CAS), and then measured serial TEOAEs in the right ear at four intervals during a total of 16 minutes of continuous CAS, followed by three more recordings after termination of CAS. RESULTS: TEOAE amplitudes were reduced with CAS during a certain period (from the immediate period to 10 minutes depending on frequency) and subsequently recovered. TEOAE suppression values in the mean amplitudes for overall frequency were 0.76 dB at the initial recording, 0.35 dB at 5 minutes, 0.44 dB at 10 minutes, and 0.33 dB at 15 minutes during CAS. The initial suppression value was significantly larger than other suppression values of 5, 10, and 15 minutes (p<0.05). In recordings obtained after CAS, TEOAE amplitude exceeded pre-acoustic amplitudes at 1 kHz, 1.5 kHz, and 2 kHz. CONCLUSIONS: The present results show the existence of the medial efferent acoustic reflex and demonstrate the time course that TEOAE suppressions present initially after CAS, showing fatigue over time. Overshooting of TEOAE was observed in recordings at several frequencies after termination of CAS.
Acoustic Stimulation ; Acoustics ; Ear ; Fatigue ; Reflex, Acoustic

BACKGROUND AND OBJECTIVES: Although the suppressive effect of the medial efferent acoustic reflex is well known, the time course of this effect over prolonged periods has yet to be fully evaluated. We assessed time-dependent change in the suppression of transient evoked otoacoustic emissions (TEOAEs) by the medial efferent acoustic reflex over a relatively long period. SUBJECTS AND METHODS: We measured TEOAEs in the right ear before contralateral acoustic stimulation (CAS), and then measured serial TEOAEs in the right ear at four intervals during a total of 16 minutes of continuous CAS, followed by three more recordings after termination of CAS. RESULTS: TEOAE amplitudes were reduced with CAS during a certain period (from the immediate period to 10 minutes depending on frequency) and subsequently recovered. TEOAE suppression values in the mean amplitudes for overall frequency were 0.76 dB at the initial recording, 0.35 dB at 5 minutes, 0.44 dB at 10 minutes, and 0.33 dB at 15 minutes during CAS. The initial suppression value was significantly larger than other suppression values of 5, 10, and 15 minutes (p<0.05). In recordings obtained after CAS, TEOAE amplitude exceeded pre-acoustic amplitudes at 1 kHz, 1.5 kHz, and 2 kHz. CONCLUSIONS: The present results show the existence of the medial efferent acoustic reflex and demonstrate the time course that TEOAE suppressions present initially after CAS, showing fatigue over time. Overshooting of TEOAE was observed in recordings at several frequencies after termination of CAS.
Acoustic Stimulation ; Acoustics ; Ear ; Fatigue ; Reflex, Acoustic

BACKGROUND AND OBJECTIVES: Changes in distortion product otoacoustic emission (DPOAE) caused by contralateral suppression (CS) allow the function of the auditory efferent system to be evaluated. Parameters affording maximum CS are preferred in terms of clinical application. Our objective was to evaluate the effects of primary levels and frequencies on DPOAE-mediated CS. SUBJECTS AND METHODS: Sixteen subjects with normal hearing participated. DPOAEs were recorded with and without contralateral acoustic stimulation; we delivered broadband noise of 65 dB SPL at f2 frequencies between 1,000 Hz and 6,727 Hz, at 8 pt/octave. The L2 was varied between 40 dB SPL and 80 dB SPL in 10-dB steps. RESULTS: L2 did not significantly affect DPOAE-mediated CS. Higher L2 levels significantly reduced the fine structure depth of both the baseline and suppressed DPOAE datasets. The amount of CS was greatly affected by the f2 frequency; lower and higher frequency ranges afforded significantly stronger suppression than did mid-frequencies within the studied range. CONCLUSIONS: Our findings suggest that DPOAE CS should be measured over a wide range of frequencies as the amount of CS seems to be highly dependent on f2. The use of a higher L2 level may be optimal when it is sought to evoke strong DPOAE-mediated suppression while simultaneously minimizing DPOAE fine structure. Our findings may assist in optimization of clinical procedures evaluating the integrity of the auditory efferent system.
Acoustic Stimulation ; Dataset ; Hearing ; Noise

No abstract available.
Acoustic Stimulation* ; Acoustics* ; Pregnancy, High-Risk*

Tinnitus is a common clinical symptom and its occurrence rate is high. It seriously affects life quality of the patients. Scientific researches show that listening some similar and none-repetitive music can relieve tinnitus to some extent. The overall music accorded with self-similarity character by the direct mapping method based on chaos. However, there were often the same tones continuous repeating a few times and tone mutations. To solve the problem, this paper proposes a new method for tinnitus rehabilitation sound synthesis based on pentatonic scale, chaos and musical instrument digital interface (MIDI). Experimental results showed that the tinnitus rehabilitation sounds were not only self-similar and incompletely reduplicate, but also no sudden changes. Thus, it has a referential significance for tinnitus treatment.
Acoustic Stimulation ; Humans ; Music ; Sound ; Tinnitus ; rehabilitation

Acoustic Stimulation ; Brain Mapping ; Hallucinations ; Humans

BACKGROUND AND OBJECTIVES: The auditory efferent system -Medial olivocochlear bundle (MOCB)-controls the sensitivity and frequency selectivity of the cochlea and maintains the cochlea for optimal acoustic signaling. Contralateral acoustic sound stimulates the MOCB and has inhibitory effects on the sound evoked amplitude response of the cochlea. There are only a few reports on the latency response of contralateral acoustic stimulation (CAS) on distortion product otoacoustic emission (DPOAE), and it has no consistent conclusion. The purpose of this study was to evaluate whether changing the latency of DPOAE by CAS could be a stable method for monitoring the function of MOCB. SUBJECTS AND METHOD: The change in the latencies of DPOAE after CAS were monitored in 24 normal hearing ears with f2 sweep paradigm. The CAS level was divided into two groups, one was under 65 dB SPL and other was over 65 dB SPL. RESULTS: As f2 frequency changed from 1 kHz to 2 kHz, the latency of DPOAE was shortened from 11.82 +/- 1.87 ms to 7.29 +/- 0.86 ms in low stimulation level (50 dB SPL) and from 10.70 +/- 2.65 ms to 6.16 +/- 1.59 ms in high stimulation level (75 dB SPL) There were no significant shortening on the latency of DPOAE after CAS in low stimulation level group. But in higher stimulation level group (75 dB SPL), DPOAE latency changed from 10.70 +/- 2.65 ms to 10.12 +/- 1.95 ms (CAS level: 35 dB SL) and to 9.76 +/- 2.97 ms (CAS level: 50 dB SL) in 1 kHz, from 6.16 +/- 1.59 ms to 5.96 +/- 1.49 ms (CAS level: 35 dB SL) and to 5.83 +/- 1.28 ms (CAS level: 50 dB SL) in 2 kHz. CONCLUSION: Changes in the latency of DPOAE after CAS is not a stable monitoring tool for the function of MOCB.
Acoustic Stimulation* ; Acoustics* ; Cochlea ; Ear ; Hearing

BACKGROUND AND OBJECTIVES: Contralateral acoustic stimulation (CAS) is known to reduce the amplitude of the transient evoked otoacoustic emission (TEOAE) in human. However, the magnitude of the suppression effect evoked by CAS is too small to overcome the problems associated with fluctuating patient conditions as well as the environmental changes. We used an alternating technique to overcome this problem and compared the efficacy of this technique with the classic technique. The aims of this study are to show reduction of the amplitude of the TEOAE with CAS and to evaluate the efficacy of the alternating technique in measuring TEOAE suppression. MATERIALS AND METHOD: TEOAE suppression was measured in 24 ears of 12 normal hearing subjects. Both the alternating technique and classic technique were used in the same subject and condition. TEOAEs were recorded with an ILO 92 dual cannel OAE analyzer. In the alternating technique, one channel was used to stimulate and record TEOAEs from the test ear while the other channel was used to deliver 40, 50 and 60 dBSPL broadband noise to the contralateral ear. But in the classic technique, one channel was used to stimulate and record TEOAEs from the test ear while the broadband noise was applied to the contralateral ear via audiometer headphone. RESULTS: The overall contralateral noise of 40, 50 and 60 dBSPL reduced the amplitude of the TEOAE but only with 60dBSPL significantly reduced in both techniques. As larger CAS was given, the suppressive effect on the TEOAEs was greater in both techniques. But the significant difference was not found between the alternating technique and the classic technique. A total test time was 6 minutes for the alternating technique and 10 minutes for the classic technique. CONCLUSION: We confirmed the reduction of the amplitude of the TEOAE with CAS using both the techniques. No significant difference was found between the results of the alternating technique and the classal technique. We found that the alternating technique thereby decreasing the chance of fluctuating patient and environmental condition.
Acoustic Stimulation* ; Acoustics* ; Ear ; Hearing ; Humans ; Noise

BACKGROUND: As the clinical-end point is not clear-cut in conscious sedation, there are no objective and feedback-providing methods to assess the depth of sedation within the levels appropriate for conscious sedation. METHODS: The investigation was carried out on 19 ASA PS 1 patients. The authors developed a system to measure the reaction time to visual (red colored flash, 40 lux for 30 msec) and auditory (beep, 1,000 Hz, 67.5 dB for 30 msec) stimulations. The authors confirmed the beeps to be audible to all the patients before the test began. When they perceived a visual or auditory stimulation, the authors instructed the patients to signal by pushing a button as soon as possible. The reaction time was defined as the time from the beginning of stimulation to the push of a button. The patients were gradually sedated with propofol TCI. The authors measured the visual and auditory reaction time and BIS after every 0.1 microgram/ml increment of the effect site concentration of propofol. RESULTS: As the effect site concentration of propofol increased, the reaction time to visual and auditory stimulations tended to be prolonged (P < 0.0001, respectively). The estimate was 409 and 498, respectively, which means the slope a in y = ax; x means unit change of the effect site concentration of propofol; y means the estimated values of the reaction time. The BIS values at loss of response to visual and auditory stimulations were 86 +/- 7 and 78 +/- 7 (mean +/- SD). CONCLUSIONS: The responses to visual and auditory stimulations were prolonged and ultimately abolished as the effect site concentration of propofol increased. The loss of response to visual stimulations preceded the loss of response to auditory stimulations. The BIS values at loss of responses to visual and auditory stimulations suggested light and moderate sedation, respectively.
Acoustic Stimulation ; Conscious Sedation* ; Humans ; Photic Stimulation ; Propofol* ; Reaction Time*