Randomized Controlled Trial of a Novel Device for Tinnitus Sound Therapy During Sleep

History of Tinnitus Research at the VA National Center for Rehabilitative Auditory Research (NCRAR), 1997-2021: Studies and Key Findings

The Veterans Affairs (VA) Rehabilitation Research & Development (RR&D) National Center for Rehabilitative Auditory Research (NCRAR) was first funded by the RR&D Service in 1997 and has been funded continuously since that time. The overall purpose of the NCRAR is to "improve the quality of life of Veterans and others with hearing and balance problems through clinical research, technology development, and education that leads to better patient care" ( www.ncrar.research.va.gov ). An important component of the research conducted at the NCRAR has been a focus on clinical and rehabilitative aspects of tinnitus. Multiple investigators have received grants to conduct tinnitus research and the present article provides an overview of this research from the NCRAR's inception through 2021.

Sound Therapy to Reduce Auditory Gain for Hyperacusis and Tinnitus

Purpose:

Hyperacusis is the most common of the different types of sound tolerance conditions. It has been defined as physical discomfort or pain when any sound reaches a certain level of loudness that would be comfortable for most people. Because hyperacusis and tinnitus occur together so often, it has been theorized that they have a common neural mechanism. A leading contender for that mechanism is enhancement of auditory gain. The purpose of this tutorial is to review the evidence that sound/acoustic therapy can reduce auditory gain and, thereby, can increase loudness tolerance for people with hyperacusis and/or suppress the percept of tinnitus.

Method:

The scientific literature was informally reviewed to identify and elucidate relationships between tinnitus, hyperacusis, sound therapy, and auditory gain.

Results:

Evidence exists, both in animal and human studies, that enhanced auditory gain is associated with hyperacusis and tinnitus. Further evidence supports the theory that certain forms of sound therapy can reduce neural hyperactivity, thereby reducing auditory gain. The evidence for sound therapy reducing auditory gain is stronger for hyperacusis than it is for tinnitus.

Conclusions:

Based on results from numerous studies, sound therapy clearly has application as a method of desensitization for hyperacusis. Enhanced auditory gain might be responsible for tinnitus, but other mechanisms have been theorized. A review of the relevant literature leads to the conclusion that some form(s) of sound therapy has the potential to suppress or eliminate tinnitus on a long-term basis. Systematic research is needed to evaluate this premise.

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.

Prevention of Noise-Induced Hearing Loss Using Investigational Medicines for the Inner Ear: Previous Trial Outcomes Should Inform Future Trial Design

Significance: Noise-induced hearing loss (NIHL) is an important public health issue resulting in decreased quality of life for affected individuals, and significant costs to employers and governmental agencies. Recent Advances: Advances in the mechanistic understanding of NIHL have prompted a growing number of proposed, in-progress, and completed clinical trials for possible protections against NIHL via antioxidants and other drug agents. Thirty-one clinical trials evaluating prevention of either temporary or permanent NIHL were identified and are reviewed. Critical Issues: This review revealed little consistency in the noise-exposed populations in which drugs are evaluated or the primary outcomes used to measure NIHL prevention. Changes in pure-tone thresholds were the most common primary outcomes; specific threshold metrics included both average hearing loss and incidence of significant hearing loss. Changes in otoacoustic emission (OAE) amplitude were relatively common secondary outcomes. Extended high-frequency (EHF) hearing and speech-in-noise perception are commonly adversely affected by noise exposure but are not consistently included in clinical trials assessing prevention of NIHL. Future Directions: Multiple criteria are available for monitoring NIHL, but the specific criterion to be used to define clinically significant otoprotection remains a topic of discussion. Audiogram-based primary outcome measures can be combined with secondary outcomes, including OAE amplitude, EHF hearing, speech-in-noise testing, tinnitus surveys, and patient-reported outcomes. Standardization of test protocols for the above primary and secondary outcomes, and associated reporting criterion for each, would facilitate clinical trial design and comparison of results across investigational drug agents. Antioxid. Redox Signal. 36, 1171-1202.

Randomised controlled trial of interventions for bothersome tinnitus: DesyncraTM versus cognitive behavioural therapy

OBJECTIVE

Compare the relative efficacy of Desyncra^TM and Cognitive Behavioural Therapy (CBT).

DESIGN AND STUDY SAMPLE

Sixty-one participants were randomly assigned to receive either Desyncra^TM (n = 29) or CBT (n = 32). Randomisation included stratification regarding current hearing aid (HA) use. Depending on group assignment, participants attended approximately 7-12 visits. Tinnitus distress was measured using the Tinnitus Questionnaire (TQ).

RESULTS

Mean TQ scores decreased post-baseline from 5-15 points across treatment arms and strata. Model-based findings for the no-HA stratum showed a difference of -2.0 TQ points favouring Desyncra at 24-weeks, with a 90% posterior interval varying from -5.4 points favouring Desyncra to 0.8 TQ points favouring CBT. For the HA stratum, results show a difference of -1.0 TQ points favouring Desyncra, with a 90% posterior interval ranging from -4.7 points favouring Desyncra to 2.9 points favouring CBT.

CONCLUSIONS

The difference between Desyncra and CBT on average showed greater improvement with Desyncra in the no-HA stratum by about 2 TQ points. To the extent that the study sample represents a clinical population and recognising the assumptions in the design and analysis, these results suggest Desyncra is just as effective or more so than CBT in reducing tinnitus distress.

Virtual reality for tinnitus management: a randomized controlled trial

OBJECTIVE

Sound therapy (ST) and stress reduction regimens have been successfully used to manage tinnitus. Virtual reality (VR) has been used to manage chronic conditions like intractable pain. The aim of the present study was to investigate whether the use of VR in conjunction with ST revealed additional improvements in tinnitus attributes as compared to ST alone.

DESIGN

This study was a randomised controlled trial (RCT) with a cross-over design. All participants received two interventions - ST alone (control) and ST with VR stimuli (experimental). ST consisted of fractal tones while VR stimuli comprised of nature videos presented via VR goggles. A multilevel mixed-effects linear regression model was used to estimate the intervention effect.

STUDY SAMPLE

Twenty adults with subjective, continuous, chronic tinnitus participated in the study.

RESULTS

After adjusting for period and baseline tinnitus loudness, significant improvements were observed in tinnitus loudness and Tinnitus Functional Index scores. Although not statistically significant, mean minimum masking levels were lower after the experimental intervention.

CONCLUSIONS

Study participants benefitted from the use of VR in conjunction with ST in a laboratory setting. Additional effectiveness trials and blinded RCTs will be needed before validating the use of VR for tinnitus management in clinical settings.

A State-of-Art Review of Digital Technologies for the Next Generation of Tinnitus Therapeutics

Background: Digital processing has enabled the development of several generations of technology for tinnitus therapy. The first digital generation was comprised of digital Hearing Aids (HAs) and personal digital music players implementing already established sound-based therapies, as well as text based information on the internet. In the second generation Smart-phone applications (apps) alone or in conjunction with HAs resulted in more therapy options for users to select from. The 3rd generation of digital tinnitus technologies began with the emergence of many novel, largely neurophysiologically-inspired, treatment theories that drove development of processing; enabled through HAs, apps, the internet and stand-alone devices. We are now of the cusp of a 4th generation that will incorporate physiological sensors, multiple transducers and AI to personalize therapies. Aim: To review technologies that will enable the next generations of digital therapies for tinnitus. Methods: A "state-of-the-art" review was undertaken to answer the question: what digital technology could be applied to tinnitus therapy in the next 10 years? Google Scholar and PubMed were searched for the 10-year period 2011-2021. The search strategy used the following key words: "tinnitus" and ["HA," "personalized therapy," "AI" (and "methods" or "applications"), "Virtual reality," "Games," "Sensors" and "Transducers"], and "Hearables." Snowballing was used to expand the search from the identified papers. The results of the review were cataloged and organized into themes. Results: This paper identified digital technologies and research on the development of smart therapies for tinnitus. AI methods that could have tinnitus applications are identified and discussed. The potential of personalized treatments and the benefits of being able to gather data in ecologically valid settings are outlined. Conclusions: There is a huge scope for the application of digital technology to tinnitus therapy, but the uncertain mechanisms underpinning tinnitus present a challenge and many posited therapeutic approaches may not be successful. Personalized AI modeling based on biometric measures obtained through various sensor types, and assessments of individual psychology and lifestyles should result in the development of smart therapy platforms for tinnitus.

Adapting Personal Therapies Using a Mobile Application for Tinnitus Rehabilitation: A Preliminary Study

OBJECTIVES

To develop a smartphone application providing sound therapy and cognitive behavioral therapy (CBT) for treating tinnitus and performing a proof-of-concept pilot study evaluating its potential efficacy.

METHODS

An interactive smartphone application available on iOS and Android platforms was developed, which provided an 8-week tinnitus-specific CBT and personalized and frequency-matched sound therapy. Included patients presented to our tertiary clinic between 2017 and 2018, while those waitlisted were regarded as controls. Three surveys were administrated: Tinnitus Handicap Inventory (THI), Generalized Anxiety Disorder 7-item (GAD-7), and Perceived Stress Scale (PSS).

RESULTS

A total of 30 patients enrolled in this study consisting of 20 treatment and 10 control patients and mean age was 55.4 ± 11.6 years. Treatment and control patients had similar age, sex, and pre-enrolment GAD and PSS (all P > .05). Baseline THI scores were also similar between treatment and control cohorts (50.1 ± 21.9 vs 62.0 ± 20.7; P = .15). After 8 weeks, though changes in GAD and PSS scores were similar (P > .05), the treatment group reported a significantly greater improvement in THI scores (17.7 ± 15.8 vs 5.3 ± 10.5, P = .04).

CONCLUSIONS

This pilot study demonstrated potentially promising efficacy of a smartphone-based CBT and sound therapy platform for treating tinnitus and encourages future randomized controlled trials on this treatment modality.

Individualized Treatment of Tinnitus during Sleep Using Combined Tinnitus Signal and Music

INTRODUCTION

Tinnitus is a widely seen otological symptom that interferes with daily activities and causes discomfort. Tinnitus treatments can be classified into 4 main groups: pharmacological treatments, cognitive and behavioral therapy, psychological treatments, and combined treatment approaches made up of at least 2 of these 3 treatment methods.

OBJECTIVE

The aim of this study was to assess whether it would be possible to develop an individualized treatment method of tinnitus by application of a combined tinnitus signal and music during sleep.

METHODS

Forty-three ears of 30 patients who had subjective tinnitus were included. The patients were evaluated using Tinnitus Handicap Inventory, Visual Analogue Scale, and Beck Depression Inventory. The psychoacoustic parameters of tinnitus, such as tinnitus frequency and loudness, and minimal masking levels, were determined. The patients were asked to select musical melodies that they liked. The tinnitus frequency of each patient was taken as the central frequency according to ANSI 2004. All sound files were prepared as stereo channels, with 16-bit resolution and 44,100 Hz sampling rate. The root mean square power value of the music and the band noise's average root mean square power value were equalized with the "Amplification" command, and 70% of the music and 30% of wide/narrow-band noise were mixed as a stereo channel by the "Mix Paste" command. The patients were instructed to listen to that individualized music/narrow-band noise (tinnitus signal) for 2 h during sleep for a duration of 6 months.

RESULTS

Tinnitus frequencies of the patients measured prior to treatment and at the second, fourth, and sixth months of follow-up were not significantly different. A statistically significant decrease was seen in tinnitus loudness, minimal masking levels, and residual inhibition during the follow-up. Tinnitus Handicap Inventory scores decreased significantly during follow-up, and the number of patients who complained of tinnitus decreased (p < 0.05). The Visual Analogue Scale scores significantly decreased during follow-up (p < 0.05). Beck Depression Inventory scores decreased significantly during follow-up (p < 0.05).

CONCLUSION

Stimulation of the auditory and limbic systems during sleep by the tinnitus signal combined with individualized musical melodies seems an alternative, effective, and cheap method in the treatment of tinnitus.

The state of the art of sound therapy for subjective tinnitus in adults

Background:

Sound therapy is a clinically common method of tinnitus management. Various forms of sound therapy have been developed, but there are controversies regarding the selection criteria and the efficacy of different forms of sound therapy in the clinic. Our goal was to review the types and forms of sound therapy and our understanding of how the different characteristics of tinnitus patients influence their curative effects so as to provide a reference for personalized choice of tinnitus sound therapy.

Method:

Using an established methodological framework, a search of six databases including PubMed identified 43 records that met our inclusion criteria. The search strategy used the following key words: tinnitus AND (acoustic OR sound OR music) AND (treatment OR therapy OR management OR intervention OR measure).

Results:

There are various forms of sound therapy, and most of them show positive therapeutic effects. The effect of customized sound therapy is generally better than that of non-customized sound therapy, and patients with more severe initial tinnitus respond better to sound therapy.

Conclusion:

Sound therapy can effectively suppress tinnitus, at least in some patients. However, there is a lack of randomized controlled trials to identify effective management strategies. Further studies are needed to identify the most effective form of sound therapy for individualized therapy, and large, multicenter, long-term follow-up studies are still needed in order to develop more effective and targeted sound-therapy protocols. In addition, it is necessary to analyze the characteristics of individual tinnitus patients and to unify the assessment criteria of tinnitus.

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.

Current Device-based Clinical Treatments for Tinnitus

Device-based clinical treatments for tinnitus are predominantly sound based and include ear-level sound generators, hearing aids, cochlear implants, and tinnitus treatment devices. They are intended for patients with bothersome tinnitus. Bothersome tinnitus is characterized by problems with sleep, concentration, and mood. Most people with bothersome tinnitus have hearing loss and would benefit from amplification; however, not all patients are willing to use hearing aids. Tinnitus treatment devices are available to assist those who are not good candidates for amplification, and include devices used while sleeping and devices used for specified periods during the day.

Sense and Sensibility: A Review of the Behavioral Neuroscience of Tinnitus Sound Therapy and a New Typology

Tinnitus Sound Therapy is not a single strategy. It consists of many different sound types, targeting many different mechanisms. Therapies that use sound to cover, reduce attention to, or facilitate habituation of tinnitus are among the most common tinnitus treatment paradigms. Recent history has seen a proliferation of sound therapies, but they have each been criticized for having limited empirical support. In this review, Sound Therapy's modern history will be described, and a typology will be introduced and discussed in light of current behavioral neuroscience research. It will be argued that contributing factors to the limited evidence for the efficacy of Sound Therapy are its diversity, plural modes of action, and absence of a clear typology. Despite gaps in understanding the efficacy of sound's effects on tinnitus, there is compelling evidence for its multiple, but related, neurophysiological mechanisms. Evidence suggests that sound may reduce tinnitus through its presence, context, reaction, and potentially adaptation. This review provides insights into the neurocognitive basis of these tinnitus Sound Therapy modes. It concludes that a unifying classification is needed to secure and advance arguments in favor of Sound Therapy.

Tinnitus Questionnaires for Research and Clinical Use

The lack of an objective measure of tinnitus has led to self-report questionnaires as the best option to evaluate tinnitus symptoms and quantify the degree to which quality of life is negatively impacted. There are many tinnitus questionnaires to choose from and it can be difficult to decide which one is best. From an evidence-based perspective, knowing how the questionnaire is designed, including its intended purpose, can help determine if it is appropriate or not to use. For example, a questionnaire designed to screen for the presence or absence of tinnitus should not be used as an outcome measure to answer questions about treatment effectiveness. Often, using more than one questionnaire is preferable to relying on just one. This chapter will review important factors to consider when selecting a questionnaire for research purposes and/or routine clinical care.

Audiologists and Tinnitus

Purpose Although tinnitus is highly prevalent among patients receiving audiology services, audiologists are generally untrained in tinnitus management. Audiology graduate programs, as a rule, do not provide comprehensive instruction in tinnitus clinical care. Training programs that do exist are inconsistent in their recommendations. Furthermore, no standards exist to prevent the delivery of unvetted audiologic services, which can be expensive for patients. Patients seeking professional services by an audiologist, therefore, have no basis upon which to be assured they will receive research-based care. The purpose of this article is to describe the current status of tinnitus management services that exist within the general field of audiology and to suggest specific approaches for improving those services. Conclusion Audiologists may be in the best position to serve as the primary health care providers for patients experiencing tinnitus. Tinnitus care services by audiologists, however, must achieve a level of evidence-based standardization.

The Role of the Brainstem in Generating and Modulating Tinnitus

Purpose The purpose of this work is to present a perspective article summarizing ideas pertaining to the brainstem's role in generating and modulating tinnitus. It is organized in 4 sections: Part 1, the role of the brainstem as a tinnitus generator; Part 2, the role of the brainstem in modulating tinnitus; Part 3, the role of the brainstem in nonauditory comorbid conditions associated with tinnitus; and Part 4, clinical implications. In Part 1, well-established neurophysiological models are discussed providing the framework of evidence that auditory brainstem nuclei play a role in generating tinnitus. In Part 2, ideas are presented explaining modulatory effects on tinnitus related to underlying pathways originating from or projecting to brainstem auditory and nonauditory nuclei. This section addresses multiple phenomena including somatic-related, attention-mediated, and emotion-mediated changes in the tinnitus percept. In Part 3, the role of the brainstem in common nonauditory comorbidities that occur in patients with tinnitus is discussed. Part 4 presents clinical implications of these new ideas related to the brainstem's involvement in generating and modulating tinnitus. Impact Knowledge of the brainstem's involvement in generating and modulating tinnitus provides a context for health care professionals to understand the temporal relationship between tinnitus and common nonauditory comorbid conditions.

Clinical Protocol to Promote Standardization of Basic Tinnitus Services by Audiologists

Purpose Clinical services for tinnitus are needed by millions of people annually. These services have not been standardized, and patients are vulnerable to receiving services that may appear legitimate but are not based on research evidence. The purpose of this clinical focus article is to promote standardization of tinnitus services by proposing an efficient clinical protocol for audiologists. Method The suggested clinical protocol is based primarily on research conducted at the National Center for Rehabilitative Auditory Research for the past 2 decades, with the focus on 2 randomized controlled trials completed recently that showed efficacy of an audiologic protocol involving hearing aids and brief tinnitus counseling. The protocol is mostly consistent with clinical practice guidelines that have been published. Results The two National Center for Rehabilitative Auditory Research randomized controlled trials revealed significant reduction of tinnitus functional effects for both hearing aids and "combination instruments" (hearing aids with a built-in sound generator), although there were no significant differences between devices. Existing clinical practice guidelines for tinnitus are summarized with respect to their common recommendations for assessment and intervention. Conclusions A defined clinical protocol is suggested for audiologists, which includes a case history, appropriate referral, audiologic assessment, use of the Tinnitus and Hearing Survey ( Henry, Griest, et al., 2015 ), brief tinnitus counseling, hearing aids or combination instruments as warranted, follow-up assessment, and criteria for determining if further tinnitus-specific services are needed. Use of this protocol can help to promote standardization of tinnitus practice by audiologists.

Sound therapy (using amplification devices and/or sound generators) for tinnitus

BACKGROUND

Tinnitus affects 10% to 15% of the adult population, with about 20% of these experiencing symptoms that negatively affect quality of life. In England alone there are an estimated ¾ million general practice consultations every year where the primary complaint is tinnitus, equating to a major burden on healthcare services. Clinical management strategies include education and advice, relaxation therapy, tinnitus retraining therapy (TRT), cognitive behavioural therapy (CBT), sound enrichment using ear-level sound generators or hearing aids, and drug therapies to manage co-morbid symptoms such as insomnia, anxiety or depression. Hearing aids, sound generators and combination devices (amplification and sound generation within one device) are a component of many tinnitus management programmes and together with information and advice are a first line of management in audiology departments for someone who has tinnitus.

OBJECTIVES

To assess the effects of sound therapy (using amplification devices and/or sound generators) for tinnitus in adults.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL, via the Cochrane Register of Studies); Ovid MEDLINE; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 23 July 2018.

SELECTION CRITERIA

Randomised controlled trials (RCTs) recruiting adults with acute or chronic subjective idiopathic tinnitus. We included studies where the intervention involved hearing aids, sound generators or combination hearing aids and compared them to waiting list control, placebo or education/information only with no device. We also included studies comparing hearing aids to sound generators, combination hearing aids to hearing aids, and combination hearing aids to sound generators.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Our primary outcomes were tinnitus symptom severity as measured as a global score on multi-item tinnitus questionnaire and significant adverse effects as indicated by an increase in self-reported tinnitus loudness. Our secondary outcomes were depressive symptoms, symptoms of generalised anxiety, health-related quality of life and adverse effects associated with wearing the device such as pain, discomfort, tenderness or skin irritation, or ear infections. We used GRADE to assess the quality of evidence for each outcome; this is indicated in italics.

MAIN RESULTS

This review included eight studies (with a total of 590 participants). Seven studies investigated the effects of hearing aids, four combination hearing aids and three sound generators. Seven studies were parallel-group RCTs and one had a cross-over design. In general, risk of bias was unclear due to lack of detail about sequence generation and allocation concealment. There was also little or no use of blinding.No data for our outcomes were available for any of our three main comparisons (comparing hearing aids, sound generators and combination devices with a waiting list control group, placebo or education/information only). Data for our additional comparisons (comparing these devices with each other) were also few, with limited potential for data pooling.Hearing aid only versus sound generator device onlyOne study compared patients fitted with sound generators versus those fitted with hearing aids and found no difference between them in their effects on our primary outcome, tinnitus symptom severity measured with the Tinnitus Handicap Inventory (THI) at 3, 6 or 12 months (low-quality evidence). The use of both types of device was associated with a clinically significant reduction in tinnitus symptom severity.Combination hearing aid versus hearing aid onlyThree studies compared combination hearing aids with hearing aids and measured tinnitus symptom severity using the THI or Tinnitus Functional Index. When we pooled the data we found no difference between them (standardised mean difference -0.15, 95% confidence interval -0.52 to 0.22; three studies; 114 participants) (low-quality evidence). The use of both types of device was again associated with a clinically significant reduction in tinnitus symptom severity.Adverse effects were not assessed in any of the included studies.None of the studies measured the secondary outcomes of depressive symptoms or depression, anxiety symptoms or generalised anxiety, or health-related quality of life as measured by a validated instrument, nor the newly developed core outcomes tinnitus intrusiveness, ability to ignore, concentration, quality of sleep and sense of control.

AUTHORS' CONCLUSIONS

There is no evidence to support the superiority of sound therapy for tinnitus over waiting list control, placebo or education/information with no device. There is insufficient evidence to support the superiority or inferiority of any of the sound therapy options (hearing aid, sound generator or combination hearing aid) over each other. The quality of evidence for the reported outcomes, assessed using GRADE, was low. Using a combination device, hearing aid or sound generator might result in little or no difference in tinnitus symptom severity.Future research into the effectiveness of sound therapy in patients with tinnitus should use rigorous methodology. Randomisation and blinding should be of the highest quality, given the subjective nature of tinnitus and the strong likelihood of a placebo response. The CONSORT statement should be used in the design and reporting of future studies. We also recommend the use of validated, patient-centred outcome measures for research in the field of tinnitus.

Intermittent Low-level Noise Causes Negative Neural Gain in the Inferior Colliculus

The central auditory system shows a remarkable ability to rescale its neural representation of loudness following long-term, low-level acoustic exposures; even when the noise is presented intermittently. Circadian rhythms exert potent biological effects, but it remains unclear if acoustic exposures occurring during the light or dark cycle affect the neurophysiological changes involved in loudness rescaling. To address this issue we exposed rats to intermittent (12 h/day), low-level noise (10-20 kHz, 75 dB SPL) for 5 weeks; exposures occurred during either the light (inactive) or dark (active) phase of the circadian cycle. The 12-h exposures, whether occurring during the light or dark phase, did not significantly alter cochlear function as reflected in distortion product otoacoustic emissions and compound action potential responses. However, neural activity in the inferior colliculus demonstrated negative gain in a frequency- and intensity-specific manner compared to unexposed controls; the magnitude and direction of the neuroplastic changes in the inferior colliculus were largely the same regardless of whether the 12-h noise exposures occurred during the light or dark phase of the circadian cycle. These neuroplastic changes could become relevant for low-level sound therapies used to treat hyperacusis.

Drug-Induced Ototoxicity: Diagnosis and Monitoring

Ototoxicity diagnosis and management has historically been approached using a variety of methods. However, in recent years a consensus on useful and practical approaches has been developed through clinical guidelines of the American Speech Language Hearing Association, the American Academy of Audiology, and multiple clinical trials published in peer-reviewed literature. Some of the guidelines and approaches are used to detect and monitor ototoxicity, while others are used to grade adverse events. Some of the audiologic measures are primary, while others are adjunct measures and may be tailored to the specific needs of the patient or clinical trial. For some types of monitoring, such as drug-induced tinnitus or dizziness, validated paper survey instruments can be both sensitive and easy for fragile patients. This review addresses the characteristics of some of the most common clinical ototoxins and the most common methods for detecting and monitoring ototoxicity in clinical practice and clinical trials.