耳鸣掩蔽疗法与TSG助听器的临床应用

耳鸣是在无外界相应声源或电刺激的情况下．耳内或头部产生的声音感觉,即患者感到耳内或颅内有声音。据估计,大约有10％～15％的人有规律性的耳呜现象．70％的耳鸣病人伴随不同程度的听力损失。耳鸣的病因多种多样,听觉传导通路的任何病变都会引起耳鸣。单纯的耳部疾病以及全身多种疾病都可以引起耳鸣。     

The differentiation of snoring mechanisms using sound analysis

Ten subjects known to suffer from heavy snoring but not obstructive sleep apnoea were studied using the technique of sleep nasendoscopy. The mechanism of snoring was noted for each and sound recordings of the snoring noise were made. Six subjects were observed to snore using their soft palate only, three snored using only their tongue base and one snored using a combination of palate and tongue base. The sound recordings were subjected to computer analysis of waveform and frequency. Palatal flutter snoring and tongue base snoring appear to have distinct waveform and frequency patterns which allows them to be differentiated from each other.     

The incudo-malleolar joint and sound transmission losses

The question as to whether the incudo-malleolar joint (IMJ) is mobile or immobile at moderate sound pressure levels (SPLs) is addressed. Referring to the mechanical properties of elastic tissue, we suggest that the IMJ is mobile at any SPL. In order to test this hypothesis, we investigated the dynamics of the IMJ in nine temporal bones by means of laser scanning doppler vibrometry. The dynamic behavior of both ossicles, malleus and incus is described by three degrees of freedom, and transfer functions (TFs) are shown for each motion component [corrected]. We show that there is indeed relative motion between the malleus and the incus. This transmission loss affects the middle ear TF and results in a frequency dependent sound transmission loss. Some characteristics of our results are in agreement with middle ear TFs described in the literature. The increasing transmission loss towards higher frequencies is caused by relative motion between malleus and incus at the IMJ. The concept that the IMJ is functionally mobile is consistent with the physical properties of elastic tissues which most likely define the mechanics of this joint. Since the IMJ is indeed mobile at moderate sound intensities and audible frequencies the theory of the lever ratio being responsible for the characteristics of the middle ear TF must be reconsidered.     

Measurement of sound

The measurement of sound involves the analysis of frequency, intensity, and temporal dimensions of acoustic signals. Each dimension of sound can be related directly to clinically observed phenomena. Frequency information, measured in Hz, can be extracted from pure-tone and complex stimuli. Intensity represents the physical energy of a signal and is described by using the decibel scale--a logarithmic scale of ratios. Temporal characteristics of sound include duration, phase, and repetition rate. In the analysis of human hearing sensitivity, the middle ear system and its impedance characteristics also must be considered. In this article, we have reviewed some major principles of sound and have presented a series of practical clinical applications. Such principles as these help to predict and explain frequency of laryngeal tones, middle ear mechanics, ear canal resonance, real-ear measurements of hearing aids, the Articulation Index, hearing loss, understanding of speech in quiet and in noise, and the relation between hearing and speech.     

The effect of optokinetic stimulation on orientation of sound lateralization

CONCLUSIONS: The current study demonstrates that sound lateralization sensitivity during interaural time difference (ITD) discrimination may be altered by optokinetic (OK) stimulation, and that sound lateralization sensitivity of ITD discrimination may be more susceptible to OK stimulation than that of interaural intensity difference (IID) discrimination. These data suggest that nystagmus or the sensation of self-rotation induced by OK stimulation influences auditory afferent information such as sound lateralization. OBJECTIVE: Using dichotic sound, the effect of optokinetic stimulation on the orientation of sound lateralization was investigated in humans. MATERIALS AND METHODS: Subjects were studied by testing ITD and IID discrimination during OK stimulation. RESULTS: At 90 degrees/s of the light stripes angular velocity the amplitudes for the ITD discrimination tests during OK stimulation were significantly greater than those either before the beginning of OK stimulation or at 30 degrees/s (p<0.05). No significant difference in the amplitude for the IID discrimination test was observed between the results obtained before and during OK stimulation. During OK stimulation, all subjects felt that their perceptual body axes shifted toward the quick phase of OK nystagmus. In 8 of 12 subjects, the median line of amplitude for the ITD discrimination test shifted to the quick phase side of the OK nystagmus.     

Azimuthal sound source localization of various sound stimuli under different conditions

AimTo evaluate azimuthal sound-source localization performance under different conditions, with a view to optimizing a routine sound localization protocol.Material and methodTwo groups of healthy, normal-hearing subjects were tested identically, except that one had to keep their head still while the other was allowed to turn it. Sound localization was tested without and then with a right ear plug (acute auditory asymmetry) for each of the following sound stimuli: pulsed narrow-band centered on 250 Hz, continuous narrowband centered on 2000 Hz, 4000 Hz and 8000 Hz, continuous 4000 Hz warble, pulsed white noise, and word (“lac” (lake)). Root mean square error was used to calculate sound-source localization accuracy.ResultsWith fixed head, localization was significantly disturbed by the earplug for all stimuli (P < 0.05). The most discriminating stimulus was continuous 4000 Hz narrow-band: area under the ROC curve (AUC), 0.99 [95% CI, 0.95–1.01] for screening and 0.85 [0.82–0.89] for diagnosis. With mobile head, localization was significantly better than with fixed head for 4000 and 8000 Hz stimuli (P < 0.05). The most discriminating stimulus was continuous 2000 Hz narrow-band: AUC, 0.90 [0.83–0.97] for screening and 0.75 [0.71–0.79] for diagnosis. In both conditions, pulsed noise (250 Hz narrow-band, white noise or word) was less difficult to localize than continuous noise.ConclusionThe test was more sensitive with the head immobile. Continuous narrow-band stimulation centered on 4000 Hz most effectively explored interaural level difference. Pulsed narrow-band stimulation centered on 250 Hz most effectively explored interaural time difference. Testing with mobile head, closer to real-life conditions, was most effective with continuous narrow-band stimulation centered on 2000 Hz.     

The effect of blindness on horizontal plane sound source identification

The effect of blindness on sound source identification was studied. Four groups of normally-hearing adults, two sighted and two blind, participated. Subjects were tested using arrays of four and eight loudspeakers, surrounding them in the horizontal plane. One sighted group was tested in quiet. The other groups were tested in continuous 60-dB SPL white noise. Three 75-dB SPL 300-ms stimuli were localized: one-third octave noise bands, centered at 0.5 and 4 kHz, and broadband noise. Broadband noise was easiest to localize (both binaural and spectral cues available), and the 0.5-kHz noise band was the most difficult (primarily interaural temporal difference cue available). Subjects with late-onset blindness achieved significantly higher scores than the early blind and blindfolded sighted subjects. The percentage correct decreased with an increase in the number of speakers, but background noise had no effect. The results attest to the benefit of early visual experience for spatial hearing in adulthood, and demonstrate the negative impact of sudden loss of sight.     

The effect of eye position on the orientation of sound lateralization

CONCLUSIONS: The data suggest that sound lateralization sensitivity during interaural time difference (ITD) discrimination is altered by eccentric gaze and that sound lateralization shifts toward the direction of the gaze. OBJECTIVE: Using dichotic sounds, the effect of eye position on the orientation of sound lateralization was investigated in humans. SUBJECTS AND METHODS: The subjects were studied by testing ITD discrimination under different conditions of visual fixation. RESULTS: The amplitudes obtained during the ITD discrimination tests during eccentric fixation were significantly greater than those obtained while gazing straight ahead (p<0.05). The median line of amplitude obtained during the ITD discrimination test shifted toward the direction of the gaze.