A New Method for Assessing Masking and Residual Inhibition of Tinnitus

Investigation of the effectiveness of sound enrichment in the treatment of tinnitus due to hearing loss

OBJECTIVE

In previous animal studies, sound enhancement reduced tinnitus perception in cases associated with hearing loss. The aim of this study was to investigate the efficacy of sound enrichment therapy in tinnitus treatment by developing a protocol that includes criteria for psychoacoustic characteristics of tinnitus to determine whether the etiology is related to hearing loss.

METHODS

A total of 96 patients with chronic tinnitus were included in the study. Fifty-two patients in the study group and 44 patients in the placebo group considered residual inhibition (RI) outcomes and tinnitus pitches. Both groups received sound enrichment treatment with different spectrum contents. The tinnitus handicap inventory (THI), visual analog scale (VAS), minimum masking level (MML), and tinnitus loudness level (TLL) results were compared before and at 1, 3, and 6 months after treatment.

RESULTS

There was a statistically significant difference between the groups in THI, VAS, MML, and TLL scores from the first month to all months after treatment (p < .01). For the study group, there was a statistically significant decrease in THI, VAS, MML, and TLL scores in the first month (p < .01). This decrease continued at a statistically significant level in the third month of posttreatment for THI (p < .05) and at all months for VAS-1 (tinnitus severity) (p < .05) and VAS-2 (tinnitus discomfort) (p < .05).

CONCLUSION

In clinical practice, after excluding other factors related to the tinnitus etiology, sound enrichment treatment can be effective in tinnitus cases where RI is positive and the tinnitus pitch is matched with a hearing loss between 45 and 55 dB HL in a relatively short period of 1 month.

EEG spectral and microstate analysis originating residual inhibition of tinnitus induced by tailor-made notched music training

Tailor-made notched music training (TMNMT) is a promising therapy for tinnitus. Residual inhibition (RI) is one of the few interventions that can temporarily inhibit tinnitus, which is a useful technique that can be applied to tinnitus research and explore tinnitus mechanisms. In this study, RI effect of TMNMT in tinnitus was investigated mainly using behavioral tests, EEG spectral and microstate analysis. To our knowledge, this study is the first to investigate RI effect of TMNMT. A total of 44 participants with tinnitus were divided into TMNMT group (22 participants; ECnm, NMnm, RInm represent that EEG recordings with eyes closed stimuli-pre, stimuli-ing, stimuli-post by TMNMT music, respectively) and Placebo control group (22 participants; ECpb, PBpb, RIpb represent that EEG recordings with eyes closed stimuli-pre, stimuli-ing, stimuli-post by Placebo music, respectively) in a single-blind manner. Behavioral tests, EEG spectral analysis (covering delta, theta, alpha, beta, gamma frequency bands) and microstate analysis (involving four microstate classes, A to D) were employed to evaluate RI effect of TMNMT. The results of the study showed that TMNMT had a stronger inhibition ability and longer inhibition time according to the behavioral tests compared to Placebo. Spectral analysis showed that RI effect of TMNMT increased significantly the power spectral density (PSD) of delta, theta bands and decreased significantly the PSD of alpha2 band, and microstate analysis showed that RI effect of TMNMT had shorter duration (microstate B, microstate C), higher Occurrence (microstate A, microstate C, microstate D), Coverage (microstate A) and transition probabilities (microstate A to microstate B, microstate A to microstate D and microstate D to microstate A). Meanwhile, RI effect of Placebo decreased significantly the PSD of alpha2 band, and microstate analysis showed that RI effect of Placebo had shorter duration (microstate C, microstate D), higher occurrence (microstate B, microstate C), lower coverage (microstate C, microstate D), higher transition probabilities (microstate A to microstate B, microstate B to microstate A). It was also found that the intensity of tinnitus symptoms was significant positively correlated with the duration of microstate B in five subgroups (ECnm, NMnm, RInm, ECpb, PBpb). Our study provided valuable experimental evidence and practical applications for the effectiveness of TMNMT as a novel music therapy for tinnitus. The observed stronger residual inhibition (RI) ability of TMNMT supported its potential applications in tinnitus treatment. Furthermore, the temporal dynamics of EEG microstates serve as novel functional and trait markers of synchronous brain activity that contribute to a deep understanding of the neural mechanism underlying TMNMT treatment for tinnitus.

Modelling homeostatic plasticity in the auditory cortex results in neural signatures of tinnitus

Tinnitus is a clinical condition where a sound is perceived without an external sound source. Homeostatic plasticity (HSP), serving to increase neural activity as compensation for the reduced input to the auditory pathway after hearing loss, has been proposed as a mechanism underlying tinnitus. In support, animal models of tinnitus show evidence of increased neural activity after hearing loss, including increased spontaneous and sound-driven firing rate, as well as increased neural noise throughout the auditory processing pathway. Bridging these findings to human tinnitus, however, has proven to be challenging. Here we implement hearing loss-induced HSP in a Wilson-Cowan Cortical Model of the auditory cortex to predict how homeostatic principles operating at the microscale translate to the meso- to macroscale accessible through human neuroimaging. We observed HSP-induced response changes in the model that were previously proposed as neural signatures of tinnitus, but that have also been reported as correlates of hearing loss and hyperacusis. As expected, HSP increased spontaneous and sound-driven responsiveness in hearing-loss affected frequency channels of the model. We furthermore observed evidence of increased neural noise and the appearance of spatiotemporal modulations in neural activity, which we discuss in light of recent human neuroimaging findings. Our computational model makes quantitative predictions that require experimental validation, and may thereby serve as the basis of future human studies of hearing loss, tinnitus, and hyperacusis.

Reevaluating the Use of Sound Therapy for Tinnitus Management: Perspectives on Relevant Systematic Reviews

PURPOSE

Tinnitus is a highly prevalent condition that can severely reduce health functioning. In spite of extant clinical practice guidelines (CPGs), implementation of these CPGs is relatively uncommon. As a result, patients seeking professional services for tinnitus often have no assurance of receiving evidence-based care. The purpose of this tutorial was to clarify the evidence for sound therapy so that it may be included in future CPGs for tinnitus.

METHOD

"Best clinical evidence" is obtained from high-quality systematic reviews, which are generally considered the highest level of evidence. Our review of recent, comprehensive, high-quality systematic reviews of interventions for tinnitus concludes that cognitive behavioral therapy is the only effective intervention, though the strength of evidence was generally rated as low in these reviews. Although trials of sound therapy for tinnitus have been included in these reviews, they have been rated as having high risk of bias (RoB) and not included in syntheses or rated as insufficient strength of evidence.

RESULTS

Conclusions from these and other reviews have influenced recommendations made in CPGs for tinnitus. These conclusions, however, can make it appear that an intervention for tinnitus is not effective, even if the opposite is true. We contend that the strict inclusion criteria for these reviews are counterproductive and have the effect of obscuring decades of evidence demonstrating the clinical effectiveness of sound therapies for tinnitus. Ultimately, this process has resulted in many patients not receiving sound therapy, despite what should be sufficient evidence that this is an effective form of intervention.

CONCLUSION

If we rely on systematic reviews using contemporary RoB assessment criteria for studies published prior to these reporting guidelines, then we risk excluding important conclusions regarding interventions that could help patients in need.

Multidisciplinary Tinnitus Research: Challenges and Future Directions From the Perspective of Early Stage Researchers

Tinnitus can be a burdensome condition on both individual and societal levels. Many aspects of this condition remain elusive, including its underlying mechanisms, ultimately hindering the development of a cure. Interdisciplinary approaches are required to overcome long-established research challenges. This review summarizes current knowledge in various tinnitus-relevant research fields including tinnitus generating mechanisms, heterogeneity, epidemiology, assessment, and treatment development, in an effort to highlight the main challenges and provide suggestions for future research to overcome them. Four common themes across different areas were identified as future research direction: (1) Further establishment of multicenter and multidisciplinary collaborations; (2) Systematic reviews and syntheses of existing knowledge; (3) Standardization of research methods including tinnitus assessment, data acquisition, and data analysis protocols; (4) The design of studies with large sample sizes and the creation of large tinnitus-specific databases that would allow in-depth exploration of tinnitus heterogeneity.

Susceptibility to Residual Inhibition Is Associated With Hearing Loss and Tinnitus Chronicity

Residual inhibition, that is, the temporary suppression of tinnitus loudness after acoustic stimulation, is a frequently observed phenomenon that may have prognostic value for clinical applications. However, it is unclear in which subjects residual inhibition is more likely and how stable the effect of inhibition is over multiple repetitions. The primary aim of this work was to evaluate the effect of hearing loss and tinnitus chronicity on residual inhibition susceptibility. The secondary aim was to investigate the short-term repeatability of residual inhibition. Residual inhibition was assessed in 74 tinnitus subjects with 60-second narrow-band noise stimuli in 10 consecutive trials. The subjects were assigned to groups according to their depth of suppression (substantial residual inhibition vs. comparator group). In addition, a categorization in normal hearing and hearing loss groups, related to the degree of hearing loss at the frequency corresponding to the tinnitus pitch, was made. Logistic regression was used to identify factors associated with susceptibility to residual inhibition. Repeatability of residual inhibition was assessed using mixed-effects ordinal regression including poststimulus time and repetitions as factors. Tinnitus chronicity was not associated with residual inhibition for subjects with hearing loss, while a statistically significant negative association between tinnitus chronicity and residual inhibition susceptibility was observed in normal hearing subjects (odds ratio: 0.63; p = .0076). Moreover, repeated states of suppression can be stably induced, reinforcing the use of residual inhibition for within-subject comparison studies.

Comparison of Sudden Sensorineural Hearing Loss with Tinnitus and Short-Term Tinnitus

Objective

As one of the common symptoms of sudden sensorineural hearing loss (SSH), tinnitus seriously affects the life and work of SSH patients. The present study is aimed at exploring whether SSH can receive acoustic therapy and the factors that affect the efficacy of SSH acoustic therapy.

Methods

A total of 162 patients were outpatients and inpatients, 86 were SSH, and 76 were short-term tinnitus (STT). Both groups received pure tone audiometry, tinnitus matching, and residual inhibition test (RI). The Tinnitus Handicap Inventory (THI), visual analog scale with respect to tinnitus loudness (VAS), and RI in each group were evaluated. The effects of age, degree of hearing loss, and tinnitus course on the efficacy of SSH acoustic therapy were also evaluated.

Results

In the comparison of RI, THI, and VAS, there was no difference between SSH and STT (P > 0.05). SSH patients with mild hearing loss showed better acoustic therapy efficacy compared with SSH patients with severe hearing loss (P < 0.05), but there is no statistical difference in age and the course of tinnitus (P > 0.05).

Conclusion

The present study showed that SSH may improve tinnitus symptom through receiving acoustic therapy and SSH patients with mild hearing loss can get better acoustic therapy effects.

Changes in Heart Rate Variability Following Acoustic Therapy in Individuals With Tinnitus

Purpose The aim of the study was to investigate changes in autonomic function, as measured by heart rate variability, in individuals with tinnitus following acoustic therapy implemented using tinnitus maskers presented via hearing aids. Method Twenty-six individuals with tinnitus and hearing impairment completed an 8-week field trial wearing hearing aids providing acoustic therapy via three tinnitus masker options set just below minimum masking level. Tinnitus handicap was measured using the Tinnitus Handicap Inventory at baseline (before starting acoustic therapy) and posttreatment (at end of 8-week trial). Resting heart rate and heart rate variability were measured using electrocardiography at baseline and posttreatment. Results There was a significant decrease in tinnitus handicap posttreatment compared to baseline. There was no change in heart rate, but there was a significant increase in heart rate variability posttreatment compared to baseline. Conclusions Acoustic therapy using tinnitus maskers delivered via hearing aids provided tinnitus relief and produced a concurrent increase in heart rate variability, suggesting a decrease in stress. Heart rate variability is a potential biomarker for tracking efficacy of acoustic therapy; however, further research is required.

Prolonged tinnitus suppression after short-term acoustic stimulation

BACKGROUND

Tinnitus suppression following acoustic stimulation is a well-known phenomenon also termed residual inhibition (RI). Some individuals may experience prolonged RI (PRI), which can last for several hours or even days, after a single short-term acoustic stimulation. Exact mechanisms of this phenomenon are unknown and current evidence anecdotal.

OBJECTIVES

The aim of our report is to collect, present, and discuss cases of PRI from our studies on acoustic stimulation in tinnitus with the aim to better understand this phenomenon as well as its implications for individualized treatments.

METHODS

We pooled cases of PRI from four of our studies with a total sample size of n = 130. The criterion was set on a PRI duration which is at least sustained twice as long as the acoustic stimulation duration.

RESULTS

We report a total number of about 5% of all participants experiencing some form of PRI, with rates of 3%-7% across the individual studies. PRI lasted from 20 min up to several days and was induced by the first stimulus in four out of six cases. Four out of six individuals experiencing PRI were female and PRI mostly occurred when acoustic stimuli were matched to the frequency or type of the tinnitus.

CONCLUSION

PTS seems to be elicitable in a small subset of tinnitus patients which could inform future individualized treatment options. Future studies should investigate if and how identified factors like stimulus type, position, sex, and chronification grade uphold experimental scrutiny. We propose that the set of methods is furthermore extended with neurophysiology in particular.

[Reducing tinnitus intensity : Pilot study to attenuate tonal tinnitus using individually spectrally optimized near-threshold noise]

Hintergrund

Tinnitus betrifft ca. 15 % der Bevölkerung, jedoch existiert noch immer kein echtes Heilverfahren. Ein von uns entwickeltes neuartiges Erklärungsmodell erlaubt nun die Erprobung einer gezielten, an den Ursachen der Tinnitusentstehung ansetzenden Behandlung. Diese basiert auf stochastischen Resonanzphänomenen an bestimmten synaptischen Verbindungen im Hörsystem, welche gezielt durch extern zugeführtes schwellennahes Rauschen induziert werden sollen.

Fragestellung

Die vorliegende Pilotstudie soll zeigen, ob ein spektral individuell angepasstes Rauschen erfolgreich chronischen tonalen/schmalbandigen Tinnitus während der Stimulation abschwächen kann.

Material und Methoden

Bei 22 volljährigen Tinnituspatienten (46.6±16.3 Jahre; 4 Frauen) wurden Hörverlust (HV) sowie Tinnitusfrequenzen (TF) und -lautstärken (TL) audiometrisch bestimmt. Darauf basierend wurden bis zu 8 verschiedene Rauschstimuli (RS) mit je 5 Lautstärken (−20 bis +20 dB SL) erzeugt. Diese wurden über audiologische Kopfhörer in einer Schallkammer für jeweils 40 s präsentiert. Nach jeder Präsentation wurde mithilfe einer 5‑stufigen Bewertungsskala (−2 bis +2) ermittelt, ob sich die TL verändert hat.

Ergebnisse

Es fanden sich Patienten ohne Verbesserung der TL (n = 6) und solche mit Verbesserung (n = 16), wobei hier RS um die TF besonders effektiv waren. Die Gruppen zeigten post hoc deutliche Unterschiede in den Audiogrammen: Offenbar ist das hier getestete Verfahren insbesondere bei normalhörenden Tinnituspatienten und solchen mit geringgradigem HV effektiv.

Schlussfolgerung

Die subjektiv wahrgenommene TL war bei 16 von 22 Probanden für die Dauer der Stimulation reduziert. Für den möglichen Erfolg einer zukünftigen Therapie scheint der HV relevant zu sein.

Comparing Three Established Methods for Tinnitus Pitch Matching With Respect to Reliability, Matching Duration, and Subjective Satisfaction

The pitch of tinnitus sound is a key characteristic that is of importance to research and sound therapies relying on exact tinnitus pitch matches. The identification of this tinnitus pitch is a challenging task as there is no objective measurement available. During the tinnitus pitch-matching procedure, the participant identifies an external sound that is most similar to the subjective perception of the tinnitus. Several methods have been developed to perform this pitch-matching procedure with tinnitus sufferers. In this study, we aimed to compare the method of adjustment, the two-alternative forced-choice (2AFC) method, and the likeness rating (LR) with respect to reliability, matching duration, and subjective satisfaction. Fifty-nine participants with chronic tinnitus were recruited and performed five consecutive runs of tinnitus matching. The participants were randomized to the three different pitch-matching methods. The intraclass correlation coefficients were .67 for method of adjustment, .63 for 2AFC, and .69 for LR, which can be interpreted as good reliability for all the three methods. However, the 2AFC method revealed significant larger within-subject variability than the other measures. Across the five runs and the three different methods, all participants learned to perform the pitch matching faster and with better self-rated accuracy. Comparing the three pitch-matching methods, LR is more time consuming and the participants were less satisfied with the 2AFC method. Overall, the three pitch-matching methods show good reliability. However, we identified differential aspects for improvement in all methods, which are discussed in this article.

The difference in poststimulus suppression between residual inhibition and forward masking

The phenomenon of tinnitus masking (TM) and residual inhibition (RI) of tinnitus are two ways to investigate how external sounds interact with tinnitus: TM provides insight on the fusion between external sound activity and tinnitus related activity while RI provides insight on how the external sound might suppress the tinnitus related activity for a period of time. Differences in masking level between the tinnitus and an external tone with tinnitus characteristics (frequency, loudness) have previously shown a high level of heterogeneity. The difference in poststimulus suppression between the two, that is, residual inhibition for the former, and forward masking for the latter, has never been explored. This study aims to investigate minimum masking levels (MMLs) and minimum residual inhibition levels (MRILs) of tinnitus and of an external tone mimicking tinnitus while using diotic and dichotic noises. Pulsed narrowband noises (1 octave width and centered at 1kHz, frequency of the hearing loss slope, tinnitus frequency) and white noise were randomly presented to 20 tinnitus participants and 20 controls with an external tone mimicking tinnitus (4kHz, intensity level corresponding to tinnitus loudness). The MML values obtained for the masking of tinnitus and for the mimicking external sounds were very similar. On the other hand, the MRILs were significantly different between the tinnitus and the mimicking external sounds within tinnitus participants. They were also different between the tinnitus participants and the controls. Overall, for both within and between comparisons, the MRIL values were much higher to produce a poststimulus suppression for the mimicking sound than for the tinnitus. The results showed no significant differences between the diotic and dichotic conditions. These results corroborate other findings suggesting that the tinnitus-related neural activity is very different from the stimulus-related neural activity. The consequences of this last finding are discussed.

Sound Therapy for Tinnitus: Options for Audiologists

Purpose

Sound therapy to reduce the emotional and functional effects of tinnitus has been used by audiologists since the 1970s when Jack Vernon introduced the masking method to provide a sense of relief from tinnitus distress. Our group renamed masking sound as “soothing” sound and distinguished it from “interesting” and “background” sound, each of which has a different purpose for tinnitus sound therapy. Other methods of sound therapy have the potential to reduce the “sensation” of tinnitus, including notched noise, matched noise, desynchronization, and residual inhibition. The purpose of this article is to provide an overview of the different sound therapy approaches to serve as a resource for audiologists who often provide sound therapy to their patients with tinnitus.

Conclusion

Although, according to systematic reviews, sound therapy does not have strong evidence for treatment of tinnitus, it is nonetheless well evidenced both through abundant research and clinical utilization mostly by audiologists. It is unknown if any one form of sound therapy is superior to any other.

Comparing Tinnitus Tuning Curves and Psychoacoustic Tuning Curves

Tinnitus masking patterns have long been known to differ from those used for masking external sound. In the present study, we compared the shape of tinnitus tuning curves (TTCs) to psychophysical tuning curves (PTCs), the latter using as a target, an external sound that mimics the tinnitus characteristics. A secondary goal was to compare sound levels required to mask tinnitus to those required to mask tinnitus-mimicking sounds. The TTC, PTC, audiometric thresholds, tinnitus pitch, and level matching results of 32 tinnitus patients were analyzed. Narrowband noise maskers were used for both PTC and TTC procedures. Patients were categorized into three groups based on a combination of individual PTC-TTC results. Our findings indicate that in 41% of cases, the PTC was sharp (V shape), but the TTC showed a flat configuration, suggesting that the tinnitus-related activity in that subgroup does not behave as a regular stimulus-induced activity. In 30% of cases, V-shape PTC and TTC were found, indicating that the tinnitus-related activity may share common properties with stimulus-induced activity. For a masker centered at the tinnitus frequency, the tinnitus was more difficult to mask than the mimicking tone in 72% of patients; this was particularly true for the subset with V-shape PTCs and flat TTCs. These results may have implications for subtyping tinnitus and acoustic therapies, in particular those targeting the tinnitus frequency.

Amplitude Modulated Noise for Tinnitus Suppression in Tonal and Noise-Like Tinnitus

BACKGROUND

The phenomenon of short-term tinnitus suppression by different forms of acoustic stimulation is referred to as residual inhibition (RI). RI can be triggered in the majority of tinnitus cases and was found to be depending on the used intensity, length or types of sounds. Past research already stressed the impact of noise stimulation as well as the superiority of amplitude modulated (AM) pure tones at the individual tinnitus frequency for RI in tonal tinnitus. Recently a novel approach for the determination of noise-like tinnitus characteristics was proposed.

OBJECTIVES

The aim of the present study was to investigate whether in participants with noise-like tinnitus RI can be increased by AM noise stimuli according to the individual tinnitus frequency range.

METHODS

For this purpose the individual tinnitus characteristics (noise-like and tonal tinnitus) of 29 people affected by tinnitus (mean age = 55.59, 7 females, mean tinnitus duration = 159.97 months) were assessed via customizable noise-band matching. The objective was to generate bandpass filtered stimuli according to the individual tinnitus sound (individualized bandpass filtered [IBP] sounds). Subsequently, various stimuli differing in bandpass filtering and AM were tested with respect to their potential to induce RI. Participants were acoustically stimulated with 7 different types of stimuli for 3 min each and had to rate the loudness of their tinnitus after each stimuli.

RESULTS

Results indicate a general efficacy of noise stimuli for the temporary suppression of tinnitus, but no significant differences between AM and unmodulated IBP. Significantly better effects were observed for the subgroup with noise-like tinnitus (n = 14), especially directly after stimulation offset.

CONCLUSIONS

The study at hand provides further insights in potential mechanisms behind RI for different types of tinnitus. Beyond that, derived principles may qualify for new or extend current tinnitus sound therapies.

Comparison of Amplitude Modulated Sounds and Pure Tones at the Tinnitus Frequency: Residual Tinnitus Suppression and Stimulus Evaluation

Recent studies have compared tinnitus suppression, or residual inhibition, between amplitude- and frequency-modulated (AM) sounds and noises or pure tones (PT). Results are indicative, yet inconclusive, of stronger tinnitus suppression of modulated sounds especially near the tinnitus frequency. Systematic comparison of AM sounds at the tinnitus frequency has not yet been studied in depth. The current study therefore aims at further advancing this line of research by contrasting tinnitus suppression profiles of AM and PT sounds at the matched tinnitus frequency (i.e., 10 and 40 Hz AM vs. PT). Participants with chronic, tonal tinnitus (n = 29) underwent comprehensive psychometric, audiometric, tinnitus matching, and acoustic stimulation procedures. Stimuli were presented for 3 minutes in two loudness regimes (60 dB sensation level [SL], minimum masking level [MML] + 6 dB, control sound: SL -6 dB) and amplitude modulated with 0, 10, or 40 Hz. Tinnitus loudness suppression was measured after the stimulation every 30 seconds. In addition, stimuli were rated regarding their valence and arousal. Results demonstrate only trends for better tinnitus suppression for the 10 Hz modulation and presentation level of 60 dB SL compared with PT, whereas nonsignificant results are reported for 40 Hz and MML + 6 dB, respectively. Furthermore, the 10 Hz AM at 60 dB SL and the 40 Hz AM at MML + 6 dB (trend) stimuli were better tolerated as elicited by valence ratings. We conclude that 10 Hz AM sounds at the tinnitus frequency may be useful to further elucidate the phenomenon of residual inhibition.

Occupational noise exposure: A review of its effects, epidemiology, and impact with recommendations for reducing its burden

Exposure to hazardous noise is one of the most common occupational risks, both in the U.S. and worldwide. Repeated overexposure to noise at or above 85 dBA can cause permanent hearing loss, tinnitus, and difficulty understanding speech in noise. It is also associated with cardiovascular disease, depression, balance problems, and lower income. About 22 million U.S. workers are currently exposed to hazardous occupational noise. Approximately 33% of working-age adults with a history of occupational noise exposure have audiometric evidence of noise-induced hearing damage, and 16% of noise-exposed workers have material hearing impairment. While the Mining, Construction, and Manufacturing sectors typically have the highest prevalence of noise exposure and hearing loss, there are noise-exposed workers in every sector and every sector has workers with hearing loss. Noise-induced hearing loss is preventable. Increased understanding of the biological processes underlying noise damage may lead to protective pharmacologic or genetic therapies. For now, an integrated public health approach that (1) emphasizes noise control over reliance on hearing protection, (2) illustrates the full impact of hearing loss on quality of life, and (3) challenges the cultural acceptance of loud noise can substantially reduce the impact of noise on worker health.

Test-Retest Reproducibility of Response Duration in Tinnitus Patients With Positive Residual Inhibition

Purpose Functional imaging is often used to try to elucidate the pathophysiological mechanism of tinnitus. Residual inhibition, the temporary suppression of tinnitus after application of a masking noise, could be an interesting technique to modulate tinnitus perception in functional imaging paradigms. The purposes of this study were to primarily assess reproducibility of the (partial) positive residual inhibition response duration in patients with tinnitus and to explore its utility in experimental designs. Method Patients with tinnitus exhibiting a (partial) positive residual inhibition response or tinnitus reduction after a 1-min white noise presentation were selected from a broad consulting tinnitus population. In 27 patients, this response was tested 4 times: twice during initial testing and twice during a retest of the psychoacoustic tinnitus measures, 4-8 weeks after initial consultation. In 17 patients with stable residual inhibition responses, reproducibility of response duration, the duration of tinnitus reduction up to pretesting state, was analyzed. Results Initial testing showed a residual inhibition duration of 29.5 s on average. Test-retest reproducibility of response duration was shown to be reliable with an ICC(3, 4) of .871 (95% CI [0.733, 0.948]) and a standard error of measurement of 6.64 s. Conclusions This study indicates the good test-retest reproducibility of residual inhibition duration in our subset of 17 patients with stable (partial) positive residual inhibition. Residual inhibition is, therefore, a technique that can potentially be used for temporary tinnitus manipulation in experimental paradigms to unravel tinnitus pathophysiology.