SoundMind Trial: a study protocol for a randomised controlled trial for online acceptance and commitment therapy and sound therapy for tinnitus

Abstract

Introduction

Tinnitus is a common ailment that affects 10%–15% of adults worldwide. Comorbidities associated with tinnitus often include hearing loss, emotional distress and sleep disorders, with insomnia being a common issue among patients with tinnitus. Audiological and psychological approaches are typically used to treat chronic subjective tinnitus, with the combination of sound therapy and cognitive–behavioural therapy-based counselling having the strongest evidence for effectiveness. Acceptance and commitment therapy (ACT) has also shown promising effects in reducing the impact of tinnitus when delivered in groups or online. However, there is a lack of evidence on the effects of combining ACT with sound therapy for patients with tinnitus-related insomnia. Therefore, this study aims to compare the efficacy of internet-delivered ACT combined with sound therapy versus sound therapy alone for tinnitus in a superiority, two-arm randomised controlled trial.

Methods and analysis

A total of 164 patients with chronic subjective tinnitus and insomnia will be randomised to receive internet-delivered guided self-help tinnitus treatment based on ACT combined with tailored sound therapy or tailored sound therapy alone. The primary outcome is the variation in Tinnitus Handicap Inventory scores observed 2 months after randomisation between the two study groups. Secondary outcomes will include insomnia severity, sleep parameters, tinnitus loudness, tinnitus acceptance, depression and anxiety. The outcomes will be assessed at 2, 3 and 6 months post randomisation.

Ethics and dissemination

The study is approved by the review board and ethics committee of the Eye and ENT Hospital of Fudan University (approval number: 2023066-1). The findings will be disseminated through presentations at relevant conferences and peer-reviewed publications.

Trial registration number

NCT05963542.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• The study employs a combination of acceptance and commitment therapy (ACT) and tailored sound therapy to tackle insomnia associated with tinnitus.

• Comprehensive patient evaluation is ensured through the utilisation of standardised questionnaires, clinical interviews, audiometric evaluations and targeted psychoacoustic measures for tinnitus.

• The online administration of ACT and sound therapy interventions will enable widespread accessibility, allowing patients to participate regardless of geographical location, thereby enhancing the study’s reach and convenience.

• The study’s design does not include participant blinding to the interventions they receive, which could introduce bias.

• The recruitment approach may not be representative of the entire tinnitus-affected demographic, potentially limiting the generalisability of the findings.

Introduction

Tinnitus, which is described as the perception of sound without any corresponding external stimulus, is a common medical problem.¹ While the prevalence of tinnitus is around 10%–15%, it becomes bothersome and problematic for only a small proportion of patients (3%–5%).² Bothersome tinnitus can interfere with all aspects of daily life and is often accompanied by anxiety, depression and sleep disturbance.³ Due to the heterogeneity in the aetiology and maintenance of tinnitus, a single treatment modality may not be effective for all patients.⁴ Common clinical management strategies, such as education and counselling, sound therapy and cognitive–behavioural therapy (CBT), can be used to reduce the awareness of tinnitus and its impact on daily life.⁵

Insomnia is common among patients with tinnitus and can further influence the perception of tinnitus, thus reducing their quality of life,⁶ and many of the available sedative-hypnotic medications have disagreeable side-effects. CBT is the first-line evidence-based psychotherapy for tinnitus, and it aims to modify dysfunctional beliefs and behaviours in order to reduce the annoyance and distress associated with tinnitus.⁷ CBT for tinnitus includes various interventions such as psychoeducation about tinnitus, relaxation techniques, positive imagery, cognitive restructuring, sound exposure and behavioural activation.⁸ In several studies, sleep management has become an additional module in traditional CBT for tinnitus and has shown a slight improvement in sleep quality.⁹

Acceptance and commitment therapy (ACT) is a part of the ‘third wave’ of CBT and is rooted in functional contextualism and is guided by relational frame theory.¹⁰ Contextualism views the behavioural impact of thoughts and feelings as dependent on context instead of content. In this framework, ACT provides another option to reduce the influence that thoughts and feelings exert over behaviour without necessarily reducing the intensity or frequency of such thoughts and feelings, whether these include fear, hopelessness, anxiety, depression, pain or tinnitus. The general goal of ACT is to increase psychological flexibility, the ability to fully engage with the present moment as a conscious human being and the ability to continue with or change behaviour.

ACT has been found to be more effective than tinnitus retraining therapy (TRT) and to be comparable to CBT in reducing tinnitus distress.^{11 12} In addition, ACT is a transdiagnostic approach that provides broad and useful guidance across a wide range of problem areas.¹³ Evidence from randomised controlled trials suggests that ACT for tinnitus can also improve the sleep quality of patients with tinnitus.¹¹ While classical behaviour therapy techniques for insomnia, such as sleep restriction and stimulus control, were used in that study to address insomnia related to tinnitus, the ACT process of mindfulness, acceptance and defusion can indeed be used to reduce cognitive arousals and counterproductive sleep efforts.¹⁴ At the same time, increased psychological flexibility also contributes to better sleep.^{15 16} Therefore, we expect that ACT-based treatment for tinnitus will address co-occurring sleep difficulties and that patients with tinnitus and insomnia will be more likely to benefit from such treatments.

Unlike masking therapy and TRT, which are non-tailored sound therapies, recently developed tailored sound therapies individually tailor sound to match the levels hearing loss and the tinnitus parameters and seek to modify the maladaptive auditory cortex reorganisation in order to inhibit or eliminate the tinnitus.¹⁷ Tailor-made notched music training (TMNMT) for tinnitus is based on the principle that spectrally notched music can reduce cortical activity corresponding to the notch centre frequency through lateral inhibition, thereby inhibiting the overactivated neurons associated with the tinnitus frequency. TMNMT has demonstrated significant efficacy in reducing tinnitus distress and is also effective in reducing subjective tinnitus loudness and emotional disturbance.18,20

Combined approaches (such as sound therapy plus counselling) are commonly used in the management of tinnitus.²¹ In some studies, CBT and sound stimulation were combined, but the sound stimulation provided by sound-creating devices was not customised to the individual, and it could only promote tinnitus habituation by enriching the acoustic environment or by shifting the attention away from the tinnitus.²² While both ACT and tailored sound therapy are potentially effective treatments, they have not been combined in tinnitus treatment. In addition, face-to-face psychological treatment has been limited by high costs, long-waiting times and therapist availability, and internet-delivered ACT has the potential to increase the accessibility of treatment.²³

Given the limited evidence on the efficacy of combining ACT with sound therapy for patients with tinnitus-related insomnia, the proposed study aims to examine the efficacy of an internet-delivered ACT combined with a sound therapy treatment programme among a sample of people with tinnitus and insomnia compared with sound therapy alone. We hypothesise that the combination of ACT and sound therapy will be superior to sound therapy alone in reducing tinnitus distress.

Methods and analysis

Study design and setting

This will be a prospective, single-centre, parallel-group, randomised controlled trial conducted at the Eye and ENT Hospital of Fudan University in Shanghai. The hospital is a large ear, nose and throat-specialised hospital and has a sufficient number of outpatient visits to meet the target sample size. Outpatients will be randomly assigned to receive either internet-delivered guided self-help tinnitus treatment based on ACT combined with tailored sound therapy or to receive tailored sound therapy alone for 8 weeks, and all participants will be followed up for 3 months. The primary outcome is the variation in Tinnitus Handicap Inventory (THI) scores observed 2 months after randomisation between the two study groups. Secondary outcomes will include insomnia severity, sleep parameters, tinnitus loudness, tinnitus acceptance, depression and anxiety. We hypothesise that the combination of ACT and sound therapy will be superior to sound therapy alone in reducing tinnitus distress. This protocol will follow the Standard Protocol Items: Recommendations for Interventional Trials statement²⁴ (online supplemental additional file 1).

Participants

Participants who meet the following inclusion criteria will be included: (1) adults aged 18–80 years old, (2) experiencing subjective tinnitus for at least 3 months; (3) a score of 38 or more on the THI, (4) a score of 15 or more on the Insomnia Severity Index (ISI), (5) 55 dB hearing level or less for the average pure tone threshold (0.5 kHz, 1 kHz, 2 kHz) for the worse ear and (6) the ability to read and write in Chinese and use a smartphone with an internet connection to work with text-based material.

Participants who meet any of the following exclusion criteria will be excluded: (1) pulsatile tinnitus or objective tinnitus, (2) organic sleep disorders, (3) other diseases that need to be treated first (eg, infections, tumours, otosclerosis, Meniere’s disease or the acute stage of sudden sensorineural hearing loss), (4) severe mental illness or (5) undergoing other research that may affect tinnitus or sleep.

Procedure

All interested and potential participants will undergo an eligibility screening procedure at the outpatient clinic. The screening will include standardised measures of tinnitus, insomnia and potential organic sleep disorders, such as pure tone audiometry, acoustic immittance, tinnitus pitch matching and loudness matching, minimum masking level, THI score, ISI score and the Hospital Anxiety and Distress Scale (HADS) score. Eligible individuals will be invited to meet with an investigator to collect baseline data and provide informed consent (online supplemental additional file 2). The randomisation process will be conducted by an independent statistician who will use a computer-generated random number sequence to allocate participants to two groups in a 1:1 ratio without stratification. To ensure allocation concealment, the randomisation sequence will be obscured through the use of sequentially numbered opaque sealed envelopes. Recruitment of participants has started in September 2023 and is expected to end in October 2024.

This trial is single blinded and it is not possible to blind the participants or therapists due to the nature of the intervention. All outcome assessments will be conducted by research team members who are blind to the assignment, and under no circumstances will unblinding be permissible. See figure 1 for the study flow chart.

Figure 1. Study flow chart.

Intervention

All components of the intervention will be conducted online. The combined treatment group will receive ACT along with sound therapy, while the single treatment group will receive sound therapy alone. No other tinnitus or insomnia treatment will be allowed during the trial period.

Acceptance and commitment therapy

ACT for tinnitus will be guided as an internet-delivered therapy and will include structured self-help material delivered through a smartphone. Therapists will be available to provide support and guidance throughout the treatment process, and the participants and therapists will communicate via the instant messaging mobile app WeChat. The self-help material is mainly in Chinese and includes text, images and audio components. It was written by the research team based on the ACT model,¹⁰ referencing published ACT treatment manuals²⁵ and incorporating relevant research on ACT interventions for tinnitus,^{11 12} and experiential exercises and metaphors are frequently used in the intervention. The first version of the material was reviewed by a licensed psychologist with extensive experience in ACT.

In general, ACT reduces the impact of tinnitus and tinnitus-related distressing thoughts and feelings by teaching psychological techniques (eg, mindfulness techniques) to effectively deal with these while helping participants to clarify their values and to identify what is important and meaningful to them. The participants are then guided, motivated and facilitated in setting goals and taking life-enriching actions. The self-help material covers the six core processes of ACT, namely acceptance, cognitive defusion, being present, the self-as-context, values and committed action, and it emphasises psychological flexibility. The material is 34 pages long and is divided into 8 modules that include information, exercises and homework. The text and images in the modules are available in PDF format, and the audio is available for download in MP3 format. Each module will be studied over 1 week, and the treatment will last a total of 8 weeks. Participants will be asked to complete the exercises and homework assignments and to report the results of specific homework assignments weekly through WeChat. The therapist will use those reports to evaluate whether the participant has assimilated the material and is ready to move on to the next module. An outline of treatment content is presented in table 1.

Table 1. Acceptance and commitment therapy for tinnitus.

Modules	Contents	Assignment
1	Introduction to tinnitusTreatment rationaleCase conceptualisationIntroduction to mindfulnessMindful breathing (exercise)	Mindful breathing
2	The white elephant (metaphor)Creative hopelessnessPushing against the clipboard (metaphor)Tug-of-war (metaphor)	Mindful breathing
3	The thinking self and the observing selfThe mind as a storyteller (metaphor)Writing thoughts down on a card (metaphor)Defusion technique (exercise)	Name the story (exercise)Leaves in a stream (meditation)
4	Demons on the boat (metaphor)Wade through the swamp (metaphor)Acceptance of emotions (exercise)	Acceptance of emotions
5	The mind as a problem-solving machine (metaphor)Mindfully eating a raisin (exercise)	Mindful breathingMindful of morning routines and domestic chores
6	Three senses of selfThe slit lamp (metaphor)The chessboard (metaphor)The continuous you (exercise)	The continuous you
7	What values areThe compass (metaphor)Two kids in the car (metaphor)Clarifying and contacting values (exercise)	Mindful breathing
8	Mountain climbing (metaphor)Setting value-based goalsBarriers to actionBreaking commitments	The willingness and action plan

An outline of treatment content.

Sound therapy

The research team developed the Fudan Tinnitus Relieving System (FTRS) app, which provides tailored sound therapy modulation based on self-described tinnitus pitch and loudness matching.²⁶ Participants will listen to tailor-made music through the app for more than 2 hours/day. The music will play using speakers and will be kept slightly higher than the tinnitus volume for better desensitisation. The app provides tinnitus education, including popular science articles and lectures, through a tinnitus forum.

Outcome measures

Table 2 provides an overview of the outcome measures and the time points of assessment.

Table 2. Schedule of enrolment, interventions and assessments.

	Study period
	Enrolment	Allocation	Treatment		Post treatment
Timepoint	−t1	t0	1M	2M	3M	6M
Enrolment:
Eligibility screening	X
Informed consent	X
Allocation		X
Interventions:
ACT+sound therapy group			X	X
Sound therapy group			X	X
Assessments:
Tinnitus Handicap Inventory (THI)	X			X	X	X
Insomnia Severity Index (ISI)	X			X	X	X
2 weeks sleep parameters		X		X	X	X
Visual Analogue Scale (VAS)	X			X	X	X
Hospital Anxiety and Depression Scale (HADS)	X			X	X	X
Tinnitus Acceptance Questionnaire (TAQ)	X			X	X	X

Primary outcome measures

The primary outcome measure is the change in THI scores observed between the two groups at 2 months following randomisation.²⁷ The THI questionnaire is widely used in research and includes functional, emotional and catastrophic subscales. It consists of 25 questions, and answers are rated on a ‘yes’ (four points), ‘sometimes’ (two points) and ‘no’ (zero points) scale. The total score is calculated by adding up the scores for all questions and classifying the severity of tinnitus as no handicap (0–16), mild handicap (18–36), moderate handicap (38–56) and severe handicap (58–100).²⁸ In this proposed study, the validated Chinese version of the THI,²⁹ which has high test–retest reliability (r=0.98) and internal consistency(α=0.93), will be used.

Secondary outcome measures

The secondary outcome measures will include the following.

Insomnia Severity Index

The ISI is a self-report questionnaire that assesses the severity and impact of insomnia over the last 2 weeks. The questionnaire consists of seven items that evaluate the time until sleep onset, sleep maintenance, early morning awakening problems, sleep dissatisfaction, interference with daytime functioning by sleep difficulties, noticeability of sleep problems by others and distress caused by sleep difficulties. Each item is scored on a 0–4 scale, and the total score is interpreted as the absence of insomnia (0–7), subthreshold insomnia (8–14), moderate insomnia (15–21) and severe insomnia (22–28).³⁰

Sleep parameters

Objective sleep will be estimated with actigraphy. Actigraphy (Atiwatch Spectrum Plus) consists of a small watch worn on the participant’s non-dominant wrist that stores data about time and body movement. The collected data will be analysed and scored using specific algorithms to generate sleep parameters.³¹

Visual Analogue Scale (VAS)

Subjective perception of tinnitus loudness will be assessed using the VAS. Participants will be asked to rate the loudness of their tinnitus on a scale ranging from 0 (no tinnitus) to 10 (tinnitus could not be louder).

Hospital Anxiety and Distress Scale

HADS is a 14-item self-report questionnaire with two 7-item subscales that assess symptoms of anxiety (HADS-A) and depression (HADS-D).³² Each item is scored on a scale of 0–3, with each subscale ranging from 0 to 21. A threshold value of 8 or greater for the HADS-A or HADS-D indicates clinically significant symptoms of anxiety or depression.³³ The Chinese version of the HADS shows satisfactory psychometric properties.³⁴

Tinnitus Acceptance Questionnaire (TAQ)

The TAQ consists of 12 items divided into two factors—activity engagement and tinnitus suppression—and it is widely used as a measure of experiential avoidance/acceptance in relation to tinnitus. The total score is 72, with higher scores indicating a higher level of tinnitus-related acceptance.³⁵

Withdrawal

Participants will be informed that they can withdraw from the study at any time without any negative consequences on their subsequent treatment choices. Detailed records will be maintained to document the reasons for withdrawal. Additionally, any unplanned events experienced by participants during the study follow-up period, such as significant hearing loss or vertigo, will be classified as adverse events (AEs). All AEs will be recorded and reported to the chief investigator.

Trial management and quality control

Data collection will be conducted through the FTRS app, which is designed to administer validated surveys online. At the outset and for subsequent analyses, baseline and outcome information will be documented in a digital case report form. Additionally, research assistants will perform follow-up assessments by reaching out to patients to gather the necessary data. A data monitoring committee, which is independent of the trial investigators, has been established to monitor safety. This trial will be coordinated and guided by the investigators of the study team. Changes in the study protocol, the progression of the study and serious AEs will be reported to the ethics committee. Personally identifiable information will be encrypted, and all data will be kept confidential and stored on encrypted servers and password-protected devices.

Sample size

To ensure an 80% statistical power with a type I error rate of 5%, we conducted a two-sample t-test for superiority. The THI score difference after 8 weeks of intervention serves as the primary endpoint for this superiority trial. An equivalence margin of 7 points was set, reflecting the minimally clinically important difference for the THI, as identified in prior research.³⁶ Anticipating a mean difference of 15.79 between the treatment groups, and based on previous ACT studies on patients with tinnitus,¹¹ we established SD of 19.18 and 20.75 for the groups. This yielded a required sample size of 65 individuals per group. To compensate for a potential dropout rate of 20%, we aim to enrol 82 participants for each group, totaling 164 participants. Power calculations suggest that with this sample size there is over 90% power to detect differences in secondary outcomes, which include the ISI, HADS-A, HADS-D and TAQ. Participant enrolment will cease once the desired sample size has been achieved.

Statistical analyses

Data will be presented as means and SD for continuous variables and as frequencies and percentages for categorical variables. Independent t-tests and χ² tests will be used to compare the differences between the baseline characteristics of the two groups.

To accommodate the longitudinal nature of the data, a mixed-effect model will be employed to evaluate the temporal evolution of both primary and secondary outcomes. Adhering to the intention-to-treat principle, this analysis will include all participants as per their initial random assignment, irrespective of their adherence to the study protocol. In instances where missing data exceed 5%, sensitivity analyses using multiple imputation will be undertaken to assess the potential influence of such missing data. In cases where baseline imbalances that could affect the outcome exist between the treatment groups, stratified analyses will be conducted based on the pertinent baseline characteristic. The 95% CI for the average difference in outcomes between the two treatment groups will be scrutinised against the predefined margin of seven points for the THI. Should the lower limit of the 95% CI fall below –7, the intervention combining ACT with sound therapy can be regarded as having a superior effect. IBM SPSS Statistics for Windows, V.24.0 (IBM Corp.) will be used for all the statistical analyses.

Patient and public involvement

Patients and the public were not engaged in the development, execution, reporting or distribution of the findings of this study.

Discussion

Sound therapy is one of the most widely researched treatments for tinnitus and includes masking therapy, hearing aids, TRT and a variety of tailored sound therapies. TRT consists of directive counselling and sound therapy designed to reclassify tinnitus perception to a neutral signal and to achieve habituation of the tinnitus.³⁷ While the efficacy of TRT and the contribution of counselling and sound therapy components remain controversial, recent research suggests that using sound generators in TRT can enhance treatment efficiency.³⁸ Regarding tailored sound therapy, TMNMT can inhibit tinnitus by reducing evoked activity in the auditory cortex areas corresponding to the tinnitus frequency.¹⁸ Additionally, TMNMT has been shown to be more effective in reducing tinnitus distress than TRT.³⁹

CBT is currently the first-line evidence-based psychotherapy for tinnitus and can significantly reduce tinnitus distress while reducing the impact of tinnitus comorbidities such as anxiety, depression and insomnia.⁴⁰ However, newer generations of CBT, such as ACT, may improve how we treat tinnitus-related problems. For example, studies have shown that interdisciplinary ACT can significantly improve sleep in patients with chronic pain. Furthermore, psychological flexibility has been shown to be strongly associated with improved sleep.¹⁶ Therefore, it is reasonable to expect that patients with tinnitus and insomnia are more likely to benefit from ACT.

Combining sound therapy and psychological interventions has become a common approach in addressing both the physical and psychological aspects of patients with tinnitus. A recent pilot study provided personalised sound therapy and smartphone-based CBT to treat tinnitus, and the results demonstrated that the group receiving the combined intervention experienced a significant reduction in tinnitus distress compared with the waitlist group.⁴¹ Still, the efficacy of the intervention needs to be validated in a larger randomised controlled trial.

This proposed study stands out from previous studies by combining ACT and tailored sound therapy to address tinnitus-related insomnia in patients. During the recruitment period of the study, patients will be assessed with standardised questionnaires, clinical interviews, complete hearing assessments and tinnitus-specific psychoacoustic assessments. These comprehensive evaluations will aim to fully characterise the patients with tinnitus, allowing for an analysis of which types of patients are more likely to benefit from the treatment and to establish a basis for individualised tinnitus treatment. In addition, ACT and sound therapy will be delivered online, offering the advantage of easy accessibility regardless of the patient’s location. However, this mode of delivery may result in reduced contact with the therapist, potentially impacting treatment compliance.

This proposed study also has some limitations. First, participants will not be blinded to their intervention, which may introduce bias in their self-reported outcomes. Second, the study will exclude participants with profound hearing loss, which may limit the generalisability of the findings to the broader tinnitus population. Third, the recruitment strategy might not capture the full spectrum of the tinnitus population. Furthermore, the participants’ psychological status, including anxiety and depression, may impact the degree of tinnitus perception and sleep quality, which may have confounding effects.

In conclusion, this is the first study to evaluate the efficacy of ACT combined with tailored sound therapy in patients with tinnitus and insomnia. We predict that psychotherapy and sound therapy may have some synergism and will be effective in improving patients’ tinnitus and sleep disturbances. Despite its limitations, this study is expected to provide a foundation for exploring optimal treatment options for tinnitus.