Residual inhibition functions in relation to tinnitus spectra and auditory threshold shift

CONCLUSIONS: Psychoacoustic functions relating the depth and duration of tinnitus suppression ('residual inhibition') to the center frequency of band-passed noise masking sounds appear to span the region of hearing loss, as do psychoacoustic measurements of the tinnitus spectrum. The results (1) suggest that cortical map reorganization induced by hearing loss is not the principal source of the tinnitus sensation and (2) provide a necessary baseline for optimizing residual inhibition in individual cases. OBJECTIVE: To measure residual inhibition functions and tinnitus spectra using sounds spanning the region of hearing loss. MATERIALS AND METHODS: Three subject-driven, computer-based tools were developed and applied to measure psychoacoustic properties of tinnitus and residual inhibition in 32 subjects with chronic tonal, ringing, or hissing tinnitus. Residual inhibition functions were measured with band-passed noise sounds varying in center frequency up to 12.0 kHz. RESULTS: The depth and duration of residual inhibition increased with the center frequency of the band-passed noise stimuli. Near-elimination of tinnitus for up to 45 s was reported by 8/24 (33%) subjects at center frequencies above 3 kHz (these cases distributed across tinnitus types). Tinnitus spectra covered the region of hearing loss with no preponderance of frequencies near the audiometric edge of normal hearing.     

Association between tinnitus retraining therapy and a tinnitus control instrument

Objective

Tinnitus retraining therapy (TRT), which is an adaptation therapy for tinnitus based on the neurophysiological model proposed by Jastreboff in 1990,consists of directive counseling and acoustic therapy with a tinnitus control instrument (TCI) or other devices. For the past 5 years, our hospital has administered TRT characterized by the use of a TCI.

Method

In this study, we reviewed the clinical course of patients with tinnitus who presented to our outpatient clinic for tinnitus and hearing loss during the 3-year period from April 2004 to March 2007 and underwent TRT with a TCI. Among 188 patients with tinnitus (105 males and 83 females), 88 patients (51 males and 37 females, excluding dropouts) who purchased a TCI and continued therapy were included in the study.

Results

Significant improvement in Tinnitus Handicap Inventory (THI) and Visual Analogue Scale (VAS) scores was found as early as 1 month of treatment and later compared with those on initial examination, suggesting that TRT with a TCI may be an effective treatment for tinnitus. Among the noises generated by the TCI, the sound pressure output from the TCI was set at just below tinnitus loudness level both of the first adjustment and the second adjustment. Speech noise and white noise were frequently selected, whereas high-frequency noise and pink noise were infrequently selected. Speech noise was most frequently selected at the first adjustment, and the number of patients selecting white noise increased at the second adjustment. The results that we compared the two also revealed that the mean hearing level and tinnitus loudness levels were higher in the white noise group than in the speech noise group, which suggested that the inner ear disorder was more harder in the white noise group. Both the THI score and VAS grade improved after 1 month of treatment in the speech noise group, whereas improvement in these parameters was observed in the white noise group after 6 months of treatment. These results suggest that it took much longer the patients in the white noise group to improve.

Conclusion

: Significant improvement in THI and VAS scores was found as early as 1 month of treatment and later compared with those on initial examination, suggesting that TRT with a TCI may be an effective treatment for tinnitus. It resulted that many patients chose the speech noise or the white noise. And also it was indicated that noise generators set at just below mixing point with tinnitus are more effective. In this study, however, speech noise was often selected probably because of the reduced output at high frequencies and the level of comfort. As white noise produces greater sound volume, patients tended to switch from other therapeutic sound to white noise at the second adjustment. These findings may help administer acoustic therapy in the future.     

Clinical study of noise-induced deafness. Part 12: Results of tests on cases of tinnitus and evaluation

For 80 cases of noise-induced deafness, various tests on tinnitus were performed to obtain results as follows. 1) When tinnitus was analyzed by the tinnitus questionnaire, many had bilateral tinnitus all the time, while few noted changes in the tone and loudness of sound. 2) As for the tinnitus frequency obtained by the pitch match test, cases with 4 kHz or more were many, accounting for 81 percent. The average tinnitus frequency was 5500 Hz. The rate of agreement with the frequency for the maximum hearing loss was 55 percent. In cases where the tinnitus frequency was not in agreement with the frequency for the maximum hearing loss, the tinnitus frequency was noted in the lower range of tone than the frequency for the maximum hearing loss. 3) The loudness of tinnitus is measured by the loudness balance test was not more than 5 dB in 86 percent of the cases. 4) As for evaluation on the subjective expression, expressions such as "zee", "keen", "meen" were many. On the pitch-match test, most of tinnitus was of the pure tone but there might be some composed of noise judging from onomatopoeic words. As for evaluation, the subjective expression was considered close to the tinnitus frequency when emphasis is placed on 2 points of evaluation. 5) As for results of the masking test, convergence type and distance type according to the Feldmann's classification were found in many cases. 6) When the tinnitogram was classified into 5 types, the high-pitched tone obliquely dip type and the dip type accounted for 80 percent. The masking inability was noted in 9 percent. The agreement between the lowest frequency for masking in the masked cases and the tinnitus frequency in the pitch-match test was found in 82%, if similar cases are included. This shows that the tinnitus frequency can be found from the masking test as well. 7) A look at the masking level at each frequency indicated that the band noise at 125 Hz might be a sound that can be masked regardless of the tinnitus frequency. 8) The rate of RI appearance was low at 36 percent, indicating that the white noise 80 dB failed to mask tinnitus.     

Phase-shift treatment for tinnitus of cochlear origin

Phase-shift treatment is a new tinnitus therapy that aims at sound cancelling. This technique is based on a theory advocating that the induction of a sound wave with a 180° phase-shift compared to the sound experienced by the patient could result in sound cancelling, likely by negation of the cortical perception of tinnitus or residual inhibition, which can be partial or complete. The aim of our study is to compare the effect of phase-shifting generated by the tinnitus phase-out™ device between pure tone tinnitus patients (PTP) and narrow band noise tinnitus patients (NBNP). In present comparative study, we explore the effects of phase-shifting during 6 weeks of phase-out™ therapy in PTP and NBNP. Thirty-five tinnitus patients were included in the study. Twenty-one patients had pure tone tinnitus and 14 patients had narrow band noise tinnitus. The effects on tinnitus were assessed using three separate visual analogue scales (VAS), the tinnitus questionnaire, the hyperacusis questionnaire, the Beck depression inventory, a categorical scale and audiometric measurements. While no differences in VAS were seen after therapy in NBNP, tinnitus increase could be demonstrated in PTP. This increase could be demonstrated for tinnitus loudness (p = 0.002) and tinnitus annoyance (p = 0.014). In conclusion, implementation of phase-shifting did not lead to significant sound cancelling. Our results are discussed and compared to previous studies investigating the effects of phase-out™ in tinnitus patients.     

Masking of tinnitus induced by sound.

Two experiments were performed in which 8 listeners used external sound to mask the tinnitus induced by a 95-dB SPL tone presented for 1 min. Wider bandwidth noises were more effective maskers than noises of critical bandwidth, which, in turn, were more effective than tonal maskers. Contralateral maskers were often effective, but less so than ipsilateral maskers. Tuning curves showed some degree of frequency specificity that was not related to the frequency of the tinnitus-inducing tone. There were consistent and pronounced differences between individual listeners. Overall, our results indicate both similarities and differences between the masking of induced tinnitus and the masking of pathological tinnitus.     

Functional imaging of unilateral tinnitus using fMRI

CONCLUSIONS: This article shows that the inferior colliculus plays a key role in unilateral subjective tinnitus. OBJECTIVES: The major aim of this study was to determine tinnitus-related neural activity in the central auditory system of unilateral tinnitus subjects and compare this to control subjects without tinnitus. SUBJECTS AND METHODS: Functional MRI (fMRI) was performed in 10 patients (5 males) with unilateral tinnitus (5 left-sided, 5 right-sided) and 12 healthy subjects (6 males); both groups had normal hearing or mild hearing loss. fMRI experiments were performed using a 3T Philips Intera Scanner. Auditory stimuli were presented left or right and consisted of dynamically rippled broadband noise with a sound pressure level of 40 or 70 dB SPL. The responses of the inferior colliculus and the auditory cortex to the stimuli were measured. RESULTS: The response to sound in the inferior colliculus was elevated in tinnitus patients compared with controls without tinnitus.     

Acoustic measurements of objective tinnitus

Ear canal sound pressure levels were measured from a 38-year-old woman who had experienced objective tinnitus in her right ear for approximately 2 years. The tinnitus sounded like a series of "sighs" that were synchronous with her pulse rate. Because the level of the tinnitus fluctuated in a pulsing manner, it appeared to be of vascular origin. Psychoacoustically, the tinnitus behaved like a low-pass masker (cutoff frequency = 1.5 kHz) of about 40 dB SPL. This masking effect was manifested as a low-frequency hearing loss in the subject's right ear. A miniature microphone system was used to monitor the tinnitus before, during, and after a jugular-vein ligation. Because the cause of the tinnitus was only generally known, acoustically monitoring the sound as the jugular vein and/or its tributaries were systematically clamped and then released enabled the site of generation to be known exactly. By monitoring the tinnitus during surgery, the effectiveness of the corrective procedure could be immediately evaluated. Hearing sensitivity in the affected ear returned to normal limits following the elimination of the tinnitus. One year after the surgery, the tinnitus was barely audible to the woman, but only when she positioned her head a specific way. The level of the tinnitus measured in this head-turned condition was markedly lower than the level obtained preoperatively.     

Sequential sound therapy in tinnitus

Sequential sound therapy, which uses wide-band white noise distinguished by some unique characteristics, is applied in the treatment of tinnitus. The methodology is described, as are the differences from and similarities to tinnitus retraining therapy. We have performed sequential sound therapy in 26 patients from 2002 through part of 2003. Thirty-eight generators of sounds were adapted for use in this therapy and, of these, 34 incorporated an earphone. The results of sequential sound therapy in our 26 patients were compared with the results of tinnitus retraining therapy in 15 patients treated during the years 2000 and 2001. Satisfactory results obtained with sequential sound therapy totaled 100%, whereas only 33% of subjects treated with tinnitus retraining therapy obtained satisfactory results. In 6 patients who received sequential sound therapy, tinnitus disappeared altogether. In addition, no patient receiving sequential sound therapy has left the treatment protocol, whereas 53% of patients receiving tinnitus retraining therapy abandoned the treatment protocol.     

扩展高频气导听阈和耳鸣的关系

目的 :探讨纯音听阈正常的耳鸣患者扩展高频气导听阈的变化。方法 :对 4 8例纯音听阈正常的耳鸣患者作扩展高频气导听阈测试 ,并根据年龄≤ 2 5岁 (14例 ) ,2 6～ 35岁 (18例 ) ,36～ 4 5岁 (16例 )分成 3个年龄组。同时以 30例正常听力、无耳鸣的青年作为正常对照组 ,分析 4组扩展高频气导听阈与耳鸣的关系。结果 :3个年龄组患侧各频率扩展高频听阈均数与自身健侧比较 ,且与正常对照组相比差异均有统计学意义 (P <0 .0 1) ;各年龄组患侧扩展高频听阈与 3个年龄组健侧相同频率听阈比较 ,差异有统计学意义 (P <0 .0 1) ,除≤2 5岁组与 2 6～ 35岁组相比差异无统计学意义 (P >0 .0 5 )外 ,≤ 2 5岁组与正常组在 10 .0kHz,12 .0kHz和 14 .0kHz差异亦无无统计学意义 (P >0 .0 5 )。结论 :纯音听阈正常的耳鸣患者的扩展高频气导听阈并不一定正常 ,耳鸣可能是内耳早期病变的症状之一 ,但是 ,对于年龄在 30岁左右及更年长者 ,扩展高频听阈改变还可能与年龄有关。扩展高频听阈测试应作为一种常规听力检查     

Tinnitus induced by tones

Noisy sounding tinnitus was induced in 11 normally hearing subjects following monaural presentation of intense pure tones. The sensation level of a comparison noise, matched in loudness to the tinnitus by the subjects, was found to increase first rapidly and then slowly before dying away within about 90 s. The peak level of the tinnitus increased with the level of the inducing tone but was unaffected by its duration or frequency; the duration of the tinnitus was positively related to the frequency but not to the level or duration of the tone. Temporary threshold shift measured with pulsed noise generally occurred after, rather than during, the tinnitus. Substantial individual differences, particularly in the duration of the tinnitus, were apparent.     

Sequential sound therapy in tinnitus

The sequential sound therapy is a treatment for tinnitus with white noise that has some own characteristics. We describe the methodology, as well as their differences and similarities with the Tinnitus Retraining Therapy. The sequential sound therapy has been carried out to seventeen patients assisted during the year 2002. 26 generators of sound were adapted, of them, 22 had incorporated an earphone. The results of the sequential sound therapy were compared with those of the Tinnitus Retraining Therapy in 15 patients assisted during 2000 and 2001. The percentage of satisfactory results obtained with sequential sound therapy has been a 100%, while the therapy with sounds of the Tinnitus Retraining Therapy obtained a 33%. With the sequential sound therapy 6 patients had no further tinnitus. With the sequential sound therapy no patients has abandoned the treatment. With the treatment with sounds of the Tinnitus Retraining Therapy of the patients did give up the therapy 53%.     

Preference for potential tinnitus maskers: results from annoyance ratings

Using the method of magnitude estimation, annoyance ratings of thirty-six different masking sounds obtained from a group suffering from tinnitus were compared with ratings from a normal-hearing group in an attempt to assess the acceptability of potential tinnitus maskers. The key findings were as follows: In both groups bandpass noise was rated as less annoying than tones or triangular waves. The annoyance value of bandpass maskers increased with bandwidth. Interrupted maskers were rated as more annoying than continuous maskers. Most of the differences between the tinnitus and normal group could be explained in terms of the high-frequency hearing loss and loudness recruitment associated with the tinnitus group. Control over the centre frequency and the bandwidth of a noise masker was important in optimising the acceptability of the tinnitus masker.     

Masking of tinnitus compared to masking of pure tones

In 10 subjects with sensorineural tinnitus (associated with a sensorineural hearing loss and no apparent source for a tinnitus originating elsewhere), the minimum level required to mask the tinnitus was determined for tonal maskers at several masker frequencies. This tinnitus masking pattern was compared to a psychoacoustical tuning curve (PTC) in which the signal frequency and level were determined from tinnitus pitch and loudness matching. Different patterns emerged. One subject showed a near-normal PTC but required high-level maskers across the frequency range to mask the tinnitus. Another subject showed some frequency resolution in the PTC but required low-level maskers across the frequency range to mask the tinnitus. For the remaining eight subjects, the masker levels required to mask the tone were generally higher than those levels required to mask the tinnitus. In addition, it was noted that the tinnitus pitch-match frequency was sometimes associated with an increase or a decrease in threshold sensitivity, or it was found at the low-frequency edge of a steep high-frequency threshold loss. In other subjects there was no apparent relationship between the tinnitus pitch and the audiogram shape.     

Characterization of tinnitus by tinnitus patients

A questionnaire was administered to 528 tinnitus patients to obtain data on their reactions to tinnitus. Results include a discussion of: (a) population characteristics, (b) perceptual characteristics, (c) the impact of tinnitus on daily life, and (d) etiology. Significant gender differences are also discussed. Tinnitus was not an occasional phenomenon, but was present for more than 26 days per month in 74% of the patients. Other important findings about tinnitus include: (a) Hearing levels at 1000 and 4000 Hz were less than or equal to 25 dB HL for 18% of the tinnitus patients, which suggests that some patients had normal hearing or mild hearing losses; (b) the prevalence of tinnitus in patients with noise-induced hearing loss (NIHL) was 30% for males and only 3% for females; (c) about 25% of the patients reported tinnitus severity had increased since tinnitus onset; (d) the effects of tinnitus were more severe in patients who reported tinnitus as their primary complaint and in patients diagnosed as having Ménière's syndrome tinnitus; and (e) some patients reported that noise exacerbated their tinnitus, whereas others reported that a quiet background exacerbated their tinnitus.     

Characteristics of temporary noise-induced tinnitus in male and female subjects

Reversible tinnitus was induced in 10 male and 8 female normal-hearing subjects following a 5 min 110 dB SPL exposure to white noise. Temporary threshold shift (TTS) was measured at 2 and 4 kHz. Characteristics of the tinnitus were determined by means of a written questionnaire administered 5 min following termination of the noise. Most of the subjects experienced a continuous tonal tinnitus of moderate loudness. Characterization of the tinnitus regarding spectral quality, type of sound, and perceived location differed as a function of gender. No difference in TTS measured at 2 and 4 kHz was seen as a function of gender. Positive relationships of fair to moderate strength were revealed between pre-exposure thresholds, TTS, and tinnitus pitch and level.     

Psychoacoustic characterization of the tinnitus spectrum: implications for the underlying mechanisms of tinnitus

In this study, an original psychometric procedure was used in order to characterize in more detail than in previous studies the different perceptual components of tinnitus, i.e. auditory sensations which are perceived in the absence of a corresponding external acoustic stimulus. Ten subjects with chronic tinnitus were asked to rate on a numeric scale the contribution of elementary pitch sensations evoked by isolated frequency components to their overall tinnitus sensation. The resulting 'internal tinnitus spectra', which represented the estimated perceptual contribution to the tinnitus sensation as a function of frequency over a large range of frequencies, were found to occupy a wide frequency range corresponding largely to that at which hearing thresholds were abnormally elevated. In most cases, they exhibited a broad peak falling within the hearing loss range. This pattern of result suggests that in subjects with high-frequency hearing loss, tinnitus sensations, when present, resemble those evoked by high-frequency noise bands with, in some cases, a superimposed tonal-like pitch. These results confirm and extend earlier results in the literature and agree with the patients' reports; their practical implications for the design of future studies on tinnitus and theoretical implications for the understanding of the neurophysiological mechanisms underlying tinnitus are discussed. The results of an additional experiment showed that the internal tinnitus spectrum could be altered by perceptual training in a fine frequency discrimination task with tones in the frequency range of the main peak of the tinnitus spectrum.     

Comparison of acoustic therapies for tinnitus suppression: a preliminary trial

Objective: This study obtained preliminary data using two types of sound therapy to suppress tinnitus and/or reduce its functional effects: (1) Notched noise (1000–12,000?Hz notched within a 1-octave range centred around the tinnitus pitch match [PM] frequency); and (2) Matched noise (1-octave wide band of noise centred around the PM frequency). A third (Placebo) group listened to low frequency noise (250–700?Hz). Design: Participants with bothersome tinnitus were randomised into one of the three groups and instructed to listen to the acoustic stimulus for 6?hours a day for 2 weeks. Stimuli were delivered using an iPod Nano, and tinnitus counselling was not performed. Outcome measures were recorded at the 0, 2 and 4 week study visits. Study Sample: Thirty participants with constant and bothersome tinnitus were recruited and randomised. Results: All groups showed, on average, overall improvement, both immediately post-treatment and 2 weeks following treatment. Outcomes varied between groups on the different measures and at the two outcome points. Conclusion: This study showed improvement for all of the groups, lending support to the premise that any type of sound stimulation is beneficial for relieving effects of tinnitus. These results may serve as a preliminary evidence for a larger study.     

The risk of tinnitus following occupational noise exposure in workers with hearing loss or normal hearing

The purpose was to investigate the relationship between noise exposure and tinnitus among workers with normal hearing and hearing loss, respectively. We conducted a cross-sectional survey of 752 workers employed at 91 workplaces, that were investigated by means of full work-shift noise levels, questionnaire data, and bilateral pure-tone audiometry. Tinnitus was not associated with the present noise level, the duration of noise exposure, or the cumulative noise exposure if participants had normal hearing. As expected, such trends were demonstrated if participants had a hearing handicap. Based on these data, we will be cautious in ascribing tinnitus to noise exposure in our patients’ workplaces if they have a normal audiogram. Furthermore our data indicates no risk of noise-induced tinnitus at exposure levels where no hearing loss would be expected, e.g. as usually encountered in non-industrial workplaces.     

Can tinnitus be masked by band erased filtered masker? Masking tinnitus with sounds not covering the tinnitus frequency

In this study, the effectiveness of masking sound not covering the tinnitus frequency was tested against that of conventional masking sound in 117 subjects. Successful masking was observed in 72% of the former and 70% of the latter. There was no remarkable difference between the two maskers regarding the acceptability and intensity. The duration of residual inhibition, however, was smaller in the masker not covering the tinnitus frequency. The masking sound tested could be useful as an alternative when the conventional one is not accepted.