A randomized, double-blind, placebo-controlled phase 2 study of intratympanic OTO-313 in patients with moderate to severe subjective tinnitus.

PURPOSE: This was a randomized, double-blind, placebo-controlled Phase 2 study to evaluate the efficacy and safety of intratympanic OTO-313 in patients with subjective unilateral tinnitus. METHODS: Patients with moderate to severe unilateral tinnitus of 2-12 months duration were enrolled. A single intratympanic injection of OTO-313 or placebo was administered to the affected ear and patients were evaluated during a 16-weeks follow-up period. Efficacy was assessed using the Tinnitus Functional Index (TFI), daily ratings of tinnitus loudness and annoyance, and Patient Global Impression of Change (PGIC). RESULTS: Intratympanic administration of OTO-313 and placebo produced reductions in tinnitus with a similar percentage of TFI responders at Weeks 4, 8, 12, and 16. Reductions in daily ratings of tinnitus loudness and annoyance, and PGIC scores were also similar between OTO-313 and placebo groups. No significant differences in mean TFI scores between OTO-313 and placebo were observed for pre-specified strata regarding tinnitus duration (≥ 2 to ≤ 6 months and > 6 to ≤ 12 months) and TFI baseline scores (≥ 32 to ≤ 53 points and ≥ 54 to 100 points), although the results numerically favored OTO-313 in patients in the ≥ 2 to ≤ 6 months strata. These results also demonstrated an unexpectedly high placebo response particularly amongst patients with chronic tinnitus, despite training implemented to mitigate placebo response. OTO-313 was well-tolerated with a similar incidence of adverse events compared to placebo. CONCLUSIONS: OTO-313 did not demonstrate a significant treatment benefit relative to placebo due in part to a high placebo response. OTO-313 was safe and well-tolerated.

The Neural Bases of Tinnitus: Lessons from Deafness and Cochlear Implants.

Subjective tinnitus is the conscious perception of sound in the absence of any acoustic source. The literature suggests various tinnitus mechanisms, most of which invoke changes in spontaneous firing rates of central auditory neurons resulting from modification of neural gain. Here, we present an alternative model based on evidence that tinnitus is: (1) rare in people who are congenitally deaf, (2) common in people with acquired deafness, and (3) potentially suppressed by active cochlear implants used for hearing restoration. We propose that tinnitus can only develop after fast auditory fiber activity has stimulated the synapse formation between fast-spiking parvalbumin positive (PV+) interneurons and projecting neurons in the ascending auditory path and coactivated frontostriatal networks after hearing onset. Thereafter, fast auditory fiber activity promotes feedforward and feedback inhibition mediated by PV+ interneuron activity in auditory-specific circuits. This inhibitory network enables enhanced stimulus resolution, attention-driven contrast improvement, and augmentation of auditory responses in central auditory pathways (neural gain) after damage of slow auditory fibers. When fast auditory fiber activity is lost, tonic PV+ interneuron activity is diminished, resulting in the prolonged response latencies, sudden hyperexcitability, enhanced cortical synchrony, elevated spontaneous γ oscillations, and impaired attention/stress-control that have been described in previous tinnitus models. Moreover, because fast processing is gained through sensory experience, tinnitus would not exist in congenital deafness. Electrical cochlear stimulation may have the potential to reestablish tonic inhibitory networks and thus suppress tinnitus. The proposed framework unites many ideas of tinnitus pathophysiology and may catalyze cooperative efforts to develop tinnitus therapies.

The Effect of Auditory Residual Inhibition on Tinnitus and the Electroencephalogram.

OBJECTIVES: Tinnitus is the perception of sound in the absence of an external physical sound source, for some people it can severely reduce the quality of life. Acoustic residual inhibition (ARI) is a suppression of tinnitus following the cessation of a sound. The present study investigated the effect of ARI on brain activity measured using EEG. DESIGN: Thirty adult participants (mean age of 58 years) experiencing chronic tinnitus (minimum 2 years) participated. Participants were presented broad band noise at 10 dB above minimum masking level (1 min followed by 4 min of silence, 4 times) counterbalanced with a control treatment of broad band noise at threshold (1 min followed by 4 min of silence, 4 times) while 64-channel EEG was simultaneously recorded. Tinnitus loudness was measured using a 9-point tinnitus loudness rating scale. RESULTS: The ARI stimulation resulted in a self-reported reduction in tinnitus loudness in 17 of the 30 participants. Tinnitus rating reduced following stimulation but gradually returned to near baseline during 4 min of silence post sound exposure; successive sound exposures resulted in lower loudness ratings. No significant reductions in loudness rating were found with the control stimulation. The EEG showed increases in power spectral density, particularly in the alpha and gamma bands, during ARI compared to the control periods. CONCLUSIONS: These results contribute to the understanding of ARI and tinnitus. We recommend that there be a closer examination of the relationship between onset and offset of sound in both tinnitus and nontinnitus control participants to ascertain if EEG changes seen with ARI relate to tinnitus suppression or general postsound activity.

A proof-of-concept study of the benefits of a single-session of tinnitus instruction and counselling with homework on tinnitus.

Objective: The objective of this study was to provide proof-of-concept of a single session of tinnitus instruction and counselling with and without homework.Design: A mixed-method design using questionnaires and thematic evaluation of qualitative data was implemented.Study sample: Sixteen participants received instruction in a single, one-to-one counselling session; eight participants additionally undertook homework consisting of either positive visualisation augmented by sound or a workbook of written and drawing activities supporting the instruction provided in the counselling session. All participants completed questionnaires just before and 3 weeks after the intervention, half were interviewed 3 weeks following the intervention.Results: Average tinnitus functional index (TFI) scores were 45 (SD 25) before and 29 (SD 23) following counselling, with a change of 4.8 or greater recorded in 75% and change of 13 points or greater in 50% of participants. Both counselling and counselling with homework showed similar changes in the TFI. This finding was supported by the qualitative analysis from which a model consisting of the themes of counselling benefit, content, application and homework benefit was derived.Conclusions: This study provides proof-of-concept of a single tinnitus instruction and counselling session, based on an ecological model of tinnitus.

Auditory Streaming and Prediction in Tinnitus Sufferers.

OBJECTIVES: The aim of this study was to determine whether auditory streaming (segregation of incoming sounds into separate sound sources) and the ability to anticipate future auditory events are affected in tinnitus sufferers compared with nontinnitus controls with matched levels of hearing. It was hypothesized that tinnitus would result in abnormal electroencephalography responses to tone deviants and tone omissions compared to controls for frequencies near the pitch of tinnitus, and this should correspond with increased levels of cortical γ and θ oscillatory rhythms. DESIGN: Sixteen individuals with tinnitus (10 men and 6 women; age, 53.44; SD, 12.92 years) and 14 control participants (8 men and 6 women; age, 50.25; SD, 18.54 years) took part in the study. A modified version of the ABA streaming paradigm, with repeating triplet pattern of two frequencies (A and B) presented as A-B-A, was used to examine deviant-related prediction error. Omission-related prediction errors were examined using a modified version of a tone-omission paradigm. Regions of interest were frontocentral, left frontal, right frontal, and temporal lobes. RESULTS: A larger N1c waveform was elicited in the absence of any tone deviation within the left primary auditory cortex of tinnitus participants. No differences were present between groups for omissions. The only difference in oscillatory band activity between the two groups in this study was in response to tones 7 semitones different from tinnitus pitch, with significantly lower ß-2 band activity present for the tinnitus group, correlating most with activity within the right inferior occipital gyrus. CONCLUSIONS: The findings from this study imply that cortical-level auditory stream segregation is altered among individuals with tinnitus.

A review of plasticity induced by auditory and visual tetanic stimulation in humans.

Long-term potentiation is a form of synaptic plasticity thought to play an important role in learning and memory. Recently noninvasive methods have been developed to induce and measure activity similar to long-term potentiation in humans. Sensory tetani (trains of quickly repeating auditory or visual stimuli) alter the electroencephalogram in a manner similar to electrical stimulation that results in long-term potentiation. This review briefly covers the development of long-term potentiation research before focusing on in vivo human studies that produce long-term potentiation-like effects using auditory and visual stimulation. Similarities and differences between traditional (animal and brain tissue) long-term potentiation studies and human sensory tetanization studies will be discussed, as well as implications for perceptual learning. Although evidence for functional consequences of sensory tetanization remains scarce, studies involving clinical populations indicate that sensory induced plasticity paradigms may be developed into diagnostic and research tools in clinical settings. Individual differences in the effects of sensory tetanization are not well-understood and provide an interesting avenue for future research. Differences in effects found between research groups that have emerged as the field has progressed are also yet to be resolved.

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.

The performance of an automatic acoustic-based program classifier compared to hearing aid users' manual selection of listening programs.

OBJECTIVE: To compare preference for and performance of manually selected programmes to an automatic sound classifier, the Phonak AutoSense OS. DESIGN: A single blind repeated measures study. Participants were fit with Phonak Virto V90 ITE aids; preferences for different listening programmes were compared across four different sound scenarios (speech in: quiet, noise, loud noise and a car). Following a 4-week trial preferences were reassessed and the users preferred programme was compared to the automatic classifier for sound quality and hearing in noise (HINT test) using a 12 loudspeaker array. STUDY SAMPLE: Twenty-five participants with symmetrical moderate-severe sensorineural hearing loss. RESULTS: Participant preferences of manual programme for scenarios varied considerably between and within sessions. A HINT Speech Reception Threshold (SRT) advantage was observed for the automatic classifier over participant's manual selection for speech in quiet, loud noise and car noise. Sound quality ratings were similar for both manual and automatic selections. CONCLUSIONS: The use of a sound classifier is a viable alternative to manual programme selection.

The accuracy and reliability of an app-based audiometer using consumer headphones: pure tone audiometry in a normal hearing group.

OBJECTIVE: To undertake a preliminary evaluation of the test-retest reliability, and accuracy of an iPad audiometer app using commercial earphones as a low-cost alternative to a clinical audiometer in a restricted sample of normal hearing participants. DESIGN: Twenty participants self-reporting normal hearing undertook four pure-tone audiometry tests in a single session. Two tests were performed with a 2-channel Type 1 audiometer (GSI-61) using EAR insert earphones and two tests with an iPad based app (Audiogram Mobile) using Apple earbud headphones. STUDY SAMPLE: Twenty normal hearing participants (13 female and seven male participants, aged 21-26 years) were recruited for the test-retest and accuracy evaluations. RESULTS: The app resulted in different thresholds to the audiometer (F(1, 19) = 16.635, p < 0.001). However test-retest reliability was similar. The app froze or quit unexpectedly over 25% of times used. CONCLUSIONS: Audiometer apps have great potential for clinical settings, especially in resource scarce environments, but reliability should not be assumed. While a low cost-alternative to standard transducers, issues of accuracy and calibration of consumer headphones need to be addressed before such combinations can be used with confidence.

Spatial masking: Development and testing of a new tinnitus assistive technology.

Masking is widely used in the management of tinnitus, however, masking at the perceived spatial location of tinnitus has not been investigated. This article examines the development of a method for the spatial masking of tinnitus. This report consists of three studies: Study I is a proof of concept study comparing customized spatial masking to conventional bilateral masking; Study II is a prototype evaluation in which the spatial masking paradigm was compared to a bilaterally equal masker using iPods connected to hearing aids in a 4-week cross-over trial; and Study III is a 4-month crossover pilot study-using prototype hearing aid-based maskers, and in which three-dimensional (3D) masking (2 months) was compared to a Tinnitus Retraining Therapy (2 months). There was a preference for the 3D masking stimulus across all three studies. Individual changes in the Tinnitus Handicap Inventory (THI) after 2 weeks of trial (Study II) and Tinnitus Functional Index (TFI) after 2 months of trial (Study III) were observed without large group differences. The spatial masking concept was piloted successfully. The qualitative and quantitative results obtained indicate directions for future clinical trials and therapy development. This study indicates that spatial masking of tinnitus is feasible, of benefit to many participants, and warrants further trials.

The relationship between tinnitus pitch and hearing sensitivity.

Tinnitus is the phantom perception of sounds. No single theory explaining the cause of tinnitus enjoys universal acceptance, however, it is usually associated with hearing loss. The aim of this study was to investigate the relationship between tinnitus pitch and audiometry, minimum masking levels (MML), tinnitus loudness, and distortion product otoacoustic emissions (DPOAE). This was a retrospective analysis of participant's records from the University of Auckland Hearing and Tinnitus Clinic database. The sample consisted of 192 participants with chronic tinnitus (more than 18 months) who had comprehensive tinnitus assessment from March 2008 to January 2011. There were 116 males (mean = 56.5 years, SD = 12.96) and 76 females (mean = 58.7 years, SD = 13.88). Seventy-six percent of participants had a tinnitus pitch ≥8 kHz. Tinnitus pitch was most often matched to frequencies at which hearing threshold was 40-60 (T50) dBHL. There was a weak but statistically significant positive correlation between tinnitus pitch and T50 (r = 0.15 at p < 0.05). No correlation was found between tinnitus pitch and DPOAEs, MML, audiometric edge and worst threshold. The strongest audiometric predictor for tinnitus pitch was the frequency at which threshold was approximately 50 dBHL. We postulate that this may be due to a change from primarily outer hair cell damage to lesions including inner hair cells at these levels of hearing loss.

Prescription of hearing-aid output for tinnitus relief.

OBJECTIVE: Tinnitus is a perceived sound that cannot be attributed to an external source. This study attempts to identify a prescription of amplification that is optimized as a first-fit setting for tinnitus relief. DESIGN: Participants compared the effect of high frequency amplification on their tinnitus. Stimuli were 13 speech files with different amounts of high frequency amplification (three cut-off frequencies and four gain settings) to simulate the effects of a change in DSL(I/O) v5.0 prescription in the high frequencies. STUDY SAMPLE: Twenty-five participants with chronic tinnitus participated in the study. RESULTS: A 6-dB reduction to prescribed gain at 2 kHz emerged as the most preferred output (26.47% participants) to interfere with participants' tinnitus. Overall, 70.58% of the participants' preferred a 3 to 6 dB reduction in output while 29.42% preferred a similar increase across all cut-off frequencies. A trend was observed in which the higher the tinnitus pitch the more similar the preferred output to DSL(I/O) v5.0. CONCLUSION: DSL(I/O) v5.0 appears to be a good starting point for prescription of hearing-aid output for tinnitus management. Long-term benefits of different prescriptions for tinnitus still need to be ascertained.

Role of hearing AIDS in tinnitus intervention: a scoping review.

BACKGROUND: Tinnitus can have a devastating impact on the quality of life of the sufferer. Although the mechanisms underpinning tinnitus remain uncertain, hearing loss is often associated with its onset, and hearing aids are among the most commonly used tools for its management. PURPOSE: To conduct a scoping review to explore the role of hearing aids in tinnitus management. RESEARCH DESIGN: Scoping review based on the six-stage framework of Arksey and O'Malley (2005). STUDY SAMPLE: Relevant studies were identified using various databases (Scopus, Google Scholar, SpringerLink, and PubMed) and hand searching of journals and a reference list of articles. Out of 277 shortlisted articles, 29 studies (18 research studies and 11 reviews) were chosen for charting of data based on their abstracts. DATA COLLECTION AND ANALYSIS: Tinnitus assessment measures used in studies were recorded along with changes in their scores. Measures used in studies included the Tinnitus Handicap Inventory (THI), Tinnitus Handicap Questionnaire (THQ), Tinnitus Severity Index (TSI), Tinnitus Reaction Questionnaire (TRQ), German version of Tinnitus Questionnaire (TQ), Beck Depression Inventory (BDI), and visual analogue scale (VAS) of tinnitus intensity. Where possible Cohen's d effect size statistic was calculated. RESULTS: Although the quality of evidence for hearing aids' effect on tinnitus is not strong, the weight of evidence (17 research studies for, 1 against) suggests merit in using hearing aids for tinnitus management. CONCLUSIONS: The majority of studies reviewed support the use of hearing aids for tinnitus management. Clinicians should feel reassured that some evidence shows support for the use of hearing aids for treating tinnitus, but there is still a need for stronger methodology and randomized control trials.

Occupational stress amongst audiologists: compassion satisfaction, compassion fatigue, and burnout.

OBJECTIVE: This study aimed to investigate occupational stress amongst audiologists, along with quantification of their professional quality of life: Burnout, compassion fatigue, and compassion satisfaction. DESIGN: A cross-sectional postal survey research design using an audiology occupational stress questionnaire (AOSQ), and the professional quality of life (ProQOL) instrument. STUDY SAMPLE: The sample consisted of members of the New Zealand Audiological Society. One hundred and forty-five questionnaires were mailed, 82 responses were received. RESULTS: The main findings suggest that six stress factors dominate clinical audiology: (1) time demand, (2) audiological management, (3) patient contact, (4) clinical protocol, (5) patient accountability, and (6) administration or equipment. A significant relationship was found between increasing age of the audiologist and risk of acquiring burnout (chi-square (1)=6.119, p<0.05). Pearson's correlation's revealed time demand was the strongest predictor of low compassion satisfaction (r=0.327) and burnout (r=0.463), while stress associated with patient contact was the strongest predictor of compassion fatigue (r=0.352). CONCLUSIONS: This study identifies sources of stress for clinical audiologists and different factors that contribute to professional quality of life.

Tinnitus pitch, masking, and the effectiveness of hearing aids for tinnitus therapy.

OBJECTIVE: To assess the benefits of hearing aids on tinnitus according to the tinnitus reaction questionnaire (TRQ; Wilson et al, 1991), to verify whether the degree of masking provided by the hearing aid influenced the TRQ score, to examine whether the matched tinnitus pitch predicted the effectiveness of hearing aids in masking tinnitus, and to determine whether prescription of high-frequency amplification might be desirable in tinnitus management when tinnitus pitch is high. DESIGN AND STUDY SAMPLE: A retrospective evaluation of the clinical outcomes of 70 tinnitus patients fitted with hearing aids was undertaken. The primary outcome measure was the TRQ, with a secondary subjective measure of tinnitus masking. RESULTS: Participants who achieved masking with their hearing aids had greater reduction in TRQ scores. Masking was more likely to be achieved when participants had good low-frequency hearing and tinnitus pitch fell into the frequency range of the hearing aids. CONCLUSIONS: The results support the use of hearing aids for tinnitus management, and suggest that masking may be a significant contributor to hearing aid success, implying that high-frequency amplification may be effective in high-pitch tinnitus.

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.

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.

Behavioral Outcomes and Neural Network Modeling of a Novel, Putative, Recategorization Sound Therapy.

The mechanisms underlying sound's effect on tinnitus perception are unclear. Tinnitus activity appears to conflict with perceptual expectations of "real" sound, resulting in it being a salient signal. Attention diverted towards tinnitus during the later stages of object processing potentially disrupts high-order auditory streaming, and its uncertain nature results in negative psychological responses. This study investigated the benefits and neurophysiological basis of passive perceptual training and informational counseling to recategorize phantom perception as a more real auditory object. Specifically, it examined underlying psychoacoustic correlates of tinnitus and the neural activities associated with tinnitus auditory streaming and how malleable these are to change with targeted intervention. Eighteen participants (8 females, 10 males, mean age = 61.6 years) completed the study. The study consisted of 2 parts: (1) An acute exposure over 30 min to a sound that matched the person's tinnitus (Tinnitus Avatar) that was cross-faded to a selected nature sound (Cicadas, Fan, Water Sound/Rain, Birds, Water and Bird). (2) A chronic exposure for 3 months to the same "morphed" sound. A brain-inspired spiking neural network (SNN) architecture was used to model and compare differences between electroencephalography (EEG) patterns recorded prior to morphing sound presentation, during, after (3-month), and post-follow-up. Results showed that the tinnitus avatar generated was a good match to an individual's tinnitus as rated on likeness scales and was not rated as unpleasant. The five environmental sounds selected for this study were also rated as being appropriate matches to individuals' tinnitus and largely pleasant to listen to. There was a significant reduction in the Tinnitus Functional Index score and subscales of intrusiveness of the tinnitus signal and ability to concentrate with the tinnitus trial end compared to baseline. There was a significant decrease in how strong the tinnitus signal was rated as well as ratings of how easy it was to ignore the tinnitus signal on severity rating scales. Qualitative analysis found that the environmental sound interacted with the tinnitus in a positive way, but participants did not experience change in severity, however, characteristics of tinnitus, including pitch and uniformity of sound, were reported to change. The results indicate the feasibility of the computational SNN method and preliminary evidence that the sound exposure may change activation of neural tinnitus networks and greater bilateral hemispheric involvement as the sound morphs over time into natural environmental sound; particularly relating to attention and discriminatory judgments (dorsal attention network, precentral gyrus, ventral anterior network). This is the first study that attempts to recategorize tinnitus using passive auditory training to a sound that morphs from resembling the person's tinnitus to a natural sound. These findings will be used to design future-controlled trials to elucidate whether the approach used differs in effect and mechanism from conventional Broadband Noise (BBN) sound therapy.

Prediction of Acoustic Residual Inhibition of Tinnitus Using a Brain-Inspired Spiking Neural Network Model.

Auditory Residual Inhibition (ARI) is a temporary suppression of tinnitus that occurs in some people following the presentation of masking sounds. Differences in neural response to ARI stimuli may enable classification of tinnitus and a tailored approach to intervention in the future. In an exploratory study, we investigated the use of a brain-inspired artificial neural network to examine the effects of ARI on electroencephalographic function, as well as the predictive ability of the model. Ten tinnitus patients underwent two auditory stimulation conditions (constant and amplitude modulated broadband noise) at two time points and were then characterised as responders or non-responders, based on whether they experienced ARI or not. Using a spiking neural network model, we evaluated concurrent neural patterns generated across space and time from features of electroencephalographic data, capturing the neural dynamic changes before and after stimulation. Results indicated that the model may be used to predict the effect of auditory stimulation on tinnitus on an individual basis. This approach may aid in the development of predictive models for treatment selection.