The development and test–retest reliability of a method for matching perceived location of tinnitus

A scoping review of tinnitus research undertaken by New Zealand researchers: Aotearoa-an international hotspot for tinnitus innovation and collaboration

Tinnitus is a very common oto-neurological disorder of the perception of sound when no sound is present. To improve understanding of the scope, strengths and weaknesses of New Zealand tinnitus research, a critical scoping review was undertaken. The aim was to help develop priorities for future research. A review of the literature was undertaken using a 6-stage scoping review framework of Scopus and Pub Med were searched in May 2023 with the combination of following key word [Tinnitus] and country of affiliation [New Zealand]. The search of PubMed resulted in 198 articles and that of Scopus 337 articles. After initial consideration of title relevance to the study (165 from PubMed and 196 from Scopus) removal of duplicates and after reading the articles and adding from references, 208 studies were chosen for charting of data. Nine themes were identified and described: A. Epidemiology; B. Models; C. Studies in animals; D. Mechanisms; E. Assessment and prognosis; F. Pharmacotherapy; G. Neuromodulation; H. Sensory therapies; I. Clinical practice. An urgent priority for future tinnitus research in NZ must be to address the absence of cultural and ethnic diversity in participants and consideration of traditional knowledge.

Investigating the effectiveness of music therapy combined with binaural beats on chronic tinnitus: A randomized controlled trial

BACKGROUND

Binaural beat stimulation (BBS) involve presenting two sinusoidal waves with specific frequency differences to induce neural changes in the brain, often used for mental state induction and symptom reduction. However, there are limited studies on its effectiveness for tinnitus. This study aimed to assess the effectiveness of combining binaural beats with music containing nature sounds for chronic tinnitus.

METHODS

A total of 30 men, aged 45.87 on average (SD = 8.09), who had chronic tinnitus and symmetrical mild to moderate hearing loss, were included in this study. The participants were randomly assigned to two groups: MT group (Music therapy; n = 15), which received relaxing music containing the sound of sea waves, and MT + BBS group (Music therapy plus binaural beats; n = 15), which received the same music combined with alpha frequency (8 Hz) binaural beats. The therapy sessions were conducted twice a day for 15 min, over a period of 4 weeks. Outcome measures, including the Tinnitus Handicap Inventory (THI), Tinnitus Functional Index (TFI), Hospital Anxiety and Depression Scale (HADS), Visual Analog Scale (VAS) and the pitch and loudness of tinnitus were administered before, immediately after, and during the three-month follow-up period.

RESULTS

The findings revealed improvements in loudness and annoyance VAS, as well as THI total and all subscale scores in both groups (p < 0.001). Additionally, TFI total score showed improvement in both groups (MT: p = 0.001; MT + BBS: p < 0.001) except for the sense of control subscale in both groups and the cognitive subscale in the MT group after the treatment and during the three-month follow-up period. Furthermore, both groups exhibited a decrease in scores for both subscales of HADS. However, there were no significant differences between the two groups in any of the measurement outcomes (p > 0.05), except for the emotional subscale scores of TFI (p = 0.049) and the functional subscale scores of THI (p = 0.034). In other words, during the follow-up period, the MT + BBS group exhibited lower scores in these two subscales compared to the MT group.

CONCLUSION

Although our study failed to demonstrate the superiority of combining binaural beats with music, both groups experienced significant improvements. This suggest that there are potential benefits to be gained from these types of stimuli. Given the sustained effect of both methods and the even greater improvements in follow-up observed in the binaural beats group for some scales, it seems that the changes in neural response and brain waves caused by our stimulations are persistent. This necessitates further research involving brain mapping, especially with longer follow-up durations.

A scoping review of the spatial perception of tinnitus and a guideline for the minimum reporting of tinnitus location

Tinnitus spatial localisation is an essential attribute of tinnitus perception and how it is separated from other ongoing neural activity. A scoping review was undertaken to determine how tinnitus localisation is reported, the role of the perceived spatial location of tinnitus on neurophysiology and if sound presented spatially can change tinnitus perception. Following reading of the full-text articles and including articles from reference lists, 46 articles were included for review. Six themes emerged from the results. 1. Where tinnitus was localised. 2. The effects of tinnitus on localisation. 3. The mechanisms underpinning tinnitus spatial location. 4. Masking. 5. Auditory training. 6. Multisensory training and virtual reality (VR). Tinnitus is much more complex than the often-used description of 'ringing in the ears'. Tinnitus can be heard anywhere in and around the head. Spatial sound presentation and perceptual training approaches may disrupt spatial selective attention to tinnitus and appear as changes in some of the neural networks involved in sound localisation. Where tinnitus is heard is a critical aspect of its perception, but its report, even in studies purporting to study localisation, is too general. A matrix for standardised minimum reporting of tinnitus location is recommended.

A randomized single-blind controlled trial of a prototype digital polytherapeutic for tinnitus

Objective

This randomized single-blind controlled trial tested the hypothesis that a prototype digital therapeutic developed to provide goal-based counseling with personalized passive and active game-based sound therapy would provide superior tinnitus outcomes, and similar usability, to a popular passive sound therapy app over a 12 week trial period.

Methods

The digital therapeutic consisted of an app for iPhone or Android smartphone, Bluetooth bone conduction headphones, neck pillow speaker, and a cloud-based clinician dashboard to enable messaging and app personalization. The control app was a popular self-help passive sound therapy app called White Noise Lite (WN). The primary outcome measure was clinically meaningful change in Tinnitus Functional Index (TFI) between baseline and 12 weeks of therapy. Secondary tinnitus measures were the TFI total score and subscales across sessions, rating scales and the Client Oriented Scale of Improvement in Tinnitus (COSIT). Usability of the US and WN interventions were assessed using the System Usability Scale (SUS) and the mHealth App Usability Questionnaire (MAUQ). Ninety-eight participants who were smartphone app users and had chronic moderate-severe tinnitus (>6 months, TFI score > 40) were enrolled and were randomly allocated to one of the intervention groups. Thirty-one participants in the USL group and 30 in the WN group completed 12 weeks of trial.

Results

Mean changes in TFI for the USL group at 6 (16.36, SD 17.96) and 12 weeks (17.83 points, SD 19.87) were clinically meaningful (>13 points reduction), the mean change in WN scores were not clinically meaningful (6 weeks 10.77, SD 18.53; 12 weeks 10.12 points, SD 21.36). A statistically higher proportion of USL participants achieved meaningful TFI change at 6 weeks (55%) and 12 weeks (65%) than the WN group at 6 weeks (33%) and 12 weeks (43%). Mean TFI, rating and COSIT scores favored the US group but were not statistically different from WN. Usability measures were similar for both groups.

Conclusions

The USL group demonstrated a higher proportion of responders than the WN group. The usability of the USL therapeutic was similar to the established WN app. The digital polytherapeutic demonstrated significant benefit for tinnitus reduction supporting further development.

Effects of sound source localization of masking sound on perception level of simulated tinnitus

Tinnitus therapies have been combined with the use of varieties of sound/noise. For masking external sounds, location of the masker in space is important; however, effects of the spatial location of the masker on tinnitus are less understood. We aimed to test whether a masking sound location would affect the perception level of simulated tinnitus. The 4 kHz simulated tinnitus was induced in the right ear of healthy volunteers through an open-type earphone. White noise was presented to the right ear using a single-sided headphone or a speaker positioned on the right side at a distance of 1.8 m for masking the simulated tinnitus. In other sessions, monaurally recorded noise localized within the head (inside-head noise) or binaurally recorded noise localized outside the head (outside-head noise) was separately presented from a dual-sided headphone. The noise presented from a distant speaker and the outside-head noise masked the simulated tinnitus in 71.1% and 77.1% of measurements at a lower intensity compared to the noise beside the ear and the inside-head noise, respectively. In conclusion, spatial information regarding the masking noise may play a role in reducing the perception level of simulated tinnitus. Binaurally recorded sounds may be beneficial for an acoustic therapy of tinnitus.

Objective Recognition of Tinnitus Location Using Electroencephalography Connectivity Features

Purpose: Tinnitus is a common but obscure auditory disease to be studied. This study will determine whether the connectivity features in electroencephalography (EEG) signals can be used as the biomarkers for an efficient and fast diagnosis method for chronic tinnitus.

Methods: In this study, the resting-state EEG signals of tinnitus patients with different tinnitus locations were recorded. Four connectivity features [including the Phase-locking value (PLV), Phase lag index (PLI), Pearson correlation coefficient (PCC), and Transfer entropy (TE)] and two time-frequency domain features in the EEG signals were extracted, and four machine learning algorithms, included two support vector machine models (SVM), a multi-layer perception network (MLP) and a convolutional neural network (CNN), were used based on the selected features to classify different possible tinnitus sources.

Results: Classification accuracy was highest when the SVM algorithm or the MLP algorithm was applied to the PCC feature sets, achieving final average classification accuracies of 99.42 or 99.1%, respectively. And based on the PLV feature, the classification result was also particularly good. And MLP ran the fastest, with an average computing time of only 4.2 s, which was more suitable than other methods when a real-time diagnosis was required.

Conclusion: Connectivity features of the resting-state EEG signals could characterize the differentiation of tinnitus location. The connectivity features (PCC and PLV) were more suitable as the biomarkers for the objective diagnosing of tinnitus. And the results were helpful for clinicians in the initial diagnosis of tinnitus.

The spatial percept of tinnitus is associated with hearing asymmetry: Subgroup comparisons

The spatial percept of tinnitus is hypothesized as an important variable for tinnitus subtyping. Hearing asymmetry often associates with tinnitus laterality, but not always. One of the methodological limitations for cross-study comparisons is how the variables for hearing asymmetry and tinnitus spatial perception are defined. In this study, data from two independent datasets were combined (n=833 adults, age ranging from 20 to 91 years, 404 males, 429 females) to investigate characteristics of subgroups with different tinnitus spatial perception focusing on hearing asymmetry. Three principle findings emerged. First, a hearing asymmetry variable emphasizing the maximum interaural difference most strongly discriminated unilateral from bilateral tinnitus. Merging lateralized bilateral tinnitus (perceived in both ears but worse in one side) with unilateral tinnitus weakened this relationship. Second, there was an association between unilateral tinnitus and ipsilateral asymmetric hearing. Third, unilateral and bilateral tinnitus were phenotypically distinct, with unilateral tinnitus being characterized by older age, asymmetric hearing, more often wearing one hearing aid, older age at tinnitus onset, shorter tinnitus duration, and higher percentage of time being annoyed by tinnitus. We recommend that careful consideration is given to the definitions of hearing asymmetry and tinnitus spatial perception in order to improve the comparability of findings across studies.

The impact of tinnitus distress on cognition

Tinnitus is the chronic perception of a phantom sound with different levels of related distress. Past research has elucidated interactions of tinnitus distress with audiological, affective and further clinical variables. The influence of tinnitus distress on cognition is underinvestigated. Our study aims at investigating specific influences of tinnitus distress and further associated predictors on cognition in a cohort of n = 146 out-ward clinical tinnitus patients. Age, educational level, hearing loss, Tinnitus Questionnaire (TQ) score, tinnitus duration, speech in noise (SIN), stress, anxiety and depression, and psychological well-being were included as predictors of a machine learning regression approach (elastic net) in three models with scores of a multiple choice vocabulary test (MWT-B), or two trail-making tests (TMT-A and TMT-B), as dependent variables. TQ scores predicted lower MWT-B scores and higher TMT-B test completion time. Stress, emotional, and psychological variables were not found to be relevant predictors in all models with the exception of small positive influences of SIN and depression on TMT-B. Effect sizes were small to medium for all models and predictors. Results are indicative of specific influence of tinnitus distress on cognitive performance, especially on general or crystallized intelligence and executive functions. More research is needed at the delicate intersection of tinnitus distress and cognitive skills needed in daily functioning.

Emerging Topics in the Behavioral Neuroscience of Tinnitus

This volume has highlighted the many recent advances in tinnitus theory, models, diagnostics, therapies, and therapeutics. But tinnitus knowledge is far from complete. In this chapter, contributors to the Behavioral Neuroscience of Tinnitus consider emerging topics and areas of research needed in light of recent findings. New research avenues and methods to explore are discussed. Issues pertaining to current assessment, treatment, and research methods are outlined, along with recommendations on new avenues to explore with research.

Prediction of tinnitus masking benefit within a case series using a spiking neural network model

Masking has been widely used as a tinnitus therapy, with large individual differences in its effectiveness. The basis of this variation is unknown. We examined individual tinnitus and psychological responses to three masking types, energetic masking (bilateral broadband static or rain noise [BBN]), informational masking (BBN with a notch at tinnitus pitch and 3-dimensional cues) and a masker combining both effects (BBN with spatial cues). Eleven participants with chronic tinnitus were followed for 12 months, each person used each masking approach for 3 months with a 1 month washout-baseline. The Tinnitus Functional Index (TFI), Tinnitus Rating Scales, Positive and Negative Affect Scale and Depression Anxiety Stress Scales, were measured every month of treatment. Electroencephalography (EEG) and psychoacoustic assessment was undertaken at baseline and following 3 months of each masking sound. The computational modeling of EEG data was based on the framework of brain-inspired Spiking Neural Network (SNN) architecture called NeuCube, designed for this study for mapping, learning, visualizing and classifying of brain activity patterns. EEG was related to clinically significant change in the TFI using the SNN model. The SNN framework was able to predict sound therapy responders (93% accuracy) from non-responders (100% accuracy) using baseline EEG recordings. The combination of energetic and informational masking was an effective treatment sound in more individuals than the other sounds used. Although the findings are promising, they are preliminary and require confirmation in independent and larger samples.

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.

Principles and Methods for Psychoacoustic Evaluation of Tinnitus

Tinnitus, the perception of sound in the absence of a physical sound in the environment, is highly heterogeneous. It varies in its etiology, characteristics, and impact on an individual's life. The sound is commonly described as "ringing," "buzzing," "crickets," "hissing," "humming." Tinnitus can be acute or chronic, mild or disabling. It can be perceived unilaterally or, more commonly, bilaterally. The sound and its location differ from person to person and fluctuate in the same individual over a certain period of time. This heterogeneity in characterization has important implications for research and clinical practice. Identifying patterns in how tinnitus sounds and its relationship to hearing may aid in identifying different forms of tinnitus and revealing their underlying mechanisms. However, the subjective nature of characterizing tinnitus makes it difficult to reliably define and measure. This chapter will focus on reviewing the psychoacoustic assessment of tinnitus, its relationship to cognitive and behavioral aspects of tinnitus, and its neuropathophysiology. In particular, it will describe the heterogeneity of tinnitus and tinnitus matching, and how individual variability in measures may be used to guide treatment and as a prognostic factor.

Individual Reliability of the Standard Clinical Method vs Patient-Centered Tinnitus Likeness Rating for Assessment of Tinnitus Pitch and Loudness Matching

Importance

Current individualized sound therapies for tinnitus rely on tinnitus pitch assessment, which is commonly derived from the standard clinical 2-alternative forced-choice (2-AFC) approach driven by the examiner. However, this method is limited by lack of individual test-retest reliability and focuses on a single rather than multiple tinnitus frequencies.

Objective

To assess individual test-retest reliability of the 2-AFC, with a single final frequency (and corresponding loudness), and the tinnitus likeness rating (TLR), with the participant exposed to the entire audible frequency spectrum, from which 3 dominant frequencies and corresponding loudness were extracted.

Design, Setting, and Participants

In this case series, participants with tinnitus underwent testing twice with both methods at a 1-month interval by experienced clinicians from January 6 through March 17, 2017. Each clinician tested each patient only once at visit 1 or 2 in a university audiology training setting with standardized equipment and was blind to previous assessment. Participants with bilateral or unilateral chronic tinnitus for longer than 6 months, in good health, without total deafness in either ear, and without cerumen in the ear canal were recruited through advertisements (community and clinics) and word of mouth (volunteer sample). The audiologists were likewise participants in the planned comparison between TLR and 2-AFC in the test-retest measures.

Main Outcomes and Measures

Test-retest concordance with 95% CIs for each method, calculated as the proportion of participants with the same final frequency between the 2 visits (2-AFC) or with at least 1 concordant dominant frequency (TLR) as well as loudness differences of no greater than 10 dB.

Results

The study sample included 31 participants (55% men; mean [SD] age, 50.7 [13.7] years). For TLR, 26 of 31 participants had at least 1 concordant dominant frequency between the 2 visits (proportion, 0.84; 95% CI, 0.66-0.95), whereas for 2-AFC, 7 of 31 participants had a concordant final tinnitus pitch in either ear (proportion, 0.23; 95% CI, 0.10-0.41). Loudness reliability followed the same pattern, with more concordant loudness levels in the TLR (proportion, 0.73; 95% CI, 0.52-0.88) than in the 2-AFC (proportion, 0.40; 95% CI, 0.05-0.85). Mean time taken to complete the tests was less than 15 minutes, and general appreciation by participants with tinnitus and audiologists were overall similar for both.

Conclusions and Relevance

Superior test-retest concordance can be demonstrated at the individual level using the several dominant frequencies extracted from the patient-centered TLR.

A feasibility study of predictable and unpredictable surf-like sounds for tinnitus therapy using personal music players

OBJECTIVE

To evaluate the feasibility of predictable or unpredictable amplitude-modulated sounds for tinnitus therapy.

DESIGN

The study consisted of two parts. (1) An adaptation experiment. Loudness level matches and rating scales (10-point) for loudness and distress were obtained at a silent baseline and at the end of three counterbalanced 30-min exposures (silence, predictable and unpredictable). (2) A qualitative 2-week sound therapy feasibility trial. Participants took home a personal music player (PMP).

STUDY SAMPLE

Part 1: 23 individuals with chronic tinnitus and part 2: seven individuals randomly selected from Part 1.

RESULTS

Self-reported tinnitus loudness and annoyance were significantly lower than baseline ratings after acute unpredictable sound exposure. Tinnitus annoyance ratings were also significantly lower than the baseline but the effect was small. The feasibility trial identified that participant preferences for sounds varied. Three participants did not obtain any benefit from either sound. Three participants preferred unpredictable compared to predictable sounds. Some participants had difficulty using the PMP, the average self-report hours of use were low (less <1 h/day).

CONCLUSIONS

Unpredictable surf-like sounds played using a PMP is a feasible tinnitus treatment. Further work is required to improve the acceptance of the sound and ease of PMP use.

Randomized Controlled Trial of a Perceptual Training Game for Tinnitus Therapy

OBJECTIVE

Abnormal executive top-down control of attention may result in, or be a consequence of, tinnitus. On the basis of a study indicating the feasibility of a game designed to treat tinnitus, a Phase II controlled trial of an auditory attention training game was undertaken.

MATERIALS AND METHODS

Measures of tinnitus, as well as behavioral and electrophysiological measures of attention, were compared before and after 20 consecutive days of 30-minute training sessions using a game developed with LabVIEW™ software (National Instruments Corp., Austin, TX). Fifteen participants played an experimental attention training game ("Terrain"), and 16 participants played a control game ("Tetris") on their home computers.

RESULTS

Clinically significant reductions in the primary measure, the Tinnitus Functional Index (TFI), were obtained for "Terrain." The secondary measures of Tinnitus Handicap Inventory and rating scales (ability to ignore and tinnitus annoyance) were significantly improved. The reductions in the TFI were correlated with improvements in a mixed auditory-visual task (Comprehensive Attention Battery(®); NeuropsychWorks, Inc., Greensboro, NC) and reduction in N1 auditory-evoked potential latency to stimuli remote from tinnitus pitch.

CONCLUSIONS

The results suggest that the attention training game may have reduced focus on the tinnitus, potentially through improved selective attention. "Terrain" was superior to "Tetris" in the population tested and therefore shows promise as a management option for tinnitus. Further testing in a larger, more general, population would be enabled through improving the game's accessibility.