Oto is one of the few tinnitus apps to be studied in independent, university-led
randomized controlled trials. Two RCTs have enrolled 294 participants: a 96-participant
Flinders University trial (published 2025) and the 198-participant Cambridge-led DEFINE
trial, with results currently in peer review.
2Independent university RCTs
294Participants enrolled
2025First peer-reviewed paper
13.5Years follow-up combined
Research partners and funders
DEFINE trial lead
Flinders RCT lead
DEFINE clinical partner
DEFINE co-funder
Has Oto been studied in a clinical trial?
Yes. Oto has been the subject of two independent university-led randomized controlled trials: a 96-participant trial led by Flinders University (published 2025) and a 198-participant trial led by the University of Cambridge (the DEFINE trial; results in peer review). Trial registrations and publications are listed below.
Summary
At a glance
Two independent academic RCTs of Oto have been conducted to date. A
96-participant trial at Flinders University (published 2025 in Speech, Language
and Hearing) and a 198-participant trial at the University of Cambridge (the
DEFINE trial; results in peer review).
The DEFINE trial is, to our knowledge, the largest randomized controlled
trial of a digital therapy for tinnitus conducted to date. Comparator:
one-to-one therapist-delivered CBT. Design: non-inferiority. Trial registration: ISRCTN99577932. Protocol: PLOS ONE, January 2024.
CBT is the most evidence-supported psychological intervention for tinnitus, recommended by NICE (UK), AAO-HNS (US), and reviewed favorably in the 2020 Cochrane systematic review.
To our knowledge, most tinnitus apps have not been studied in a
published randomized controlled trial. Oto is one of the few exceptions.
Both trials were independently conducted by academic teams, and
partially funded by Oto Health Ltd alongside non-commercial co-funders: Flinders
University (Flinders trial) and the UK government’s innovation agency, Innovate UK
(DEFINE).
Expert consensus
Why CBT is the leading evidence-based approach for tinnitus
Cognitive behavioral therapy (CBT) is the most evidence-supported psychological
intervention for tinnitus. It is recommended in clinical guidelines from the UK’s
National Institute for Health and Care Excellence (NICE), the American Academy of
Otolaryngology, Head and Neck Surgery (AAO-HNS), and reviewed favorably by the Cochrane
Collaboration. CBT does not aim to silence tinnitus; it helps people change the way they
think about and respond to it, reducing its impact on quality of life.
NICE
United Kingdom
Consider digital tinnitus-related CBT for adults with tinnitus that is causing distress.
The UK National Institute for Health and Care Excellence (NICE) clinical guideline NG155, Tinnitus: assessment and management, lists digital tinnitus-related CBT among the first steps a clinician should consider when offering specific tinnitus management.
The American Academy of Otolaryngology, Head and Neck Surgery (AAO-HNS) clinical practice guideline for tinnitus issues a Recommendation (the highest evidence grade in the guideline) that clinicians should recommend CBT to patients with persistent, bothersome tinnitus.
A 2020 Cochrane systematic review of randomized controlled trials of CBT for tinnitus in adults concluded that CBT may reduce the negative impact of tinnitus on quality of life, with effects considered clinically meaningful.
CBT is the most evidence-supported psychological intervention for tinnitus, recommended by NICE, AAO-HNS, and Cochrane.
NICE specifically recommends digital CBT as a first step in tinnitus management.
AAO-HNS issues its highest-grade recommendation that clinicians should recommend CBT to patients with persistent, bothersome tinnitus.
The 2020 Cochrane systematic review concluded that CBT may reduce the negative impact of tinnitus on quality of life.
The program
How Oto delivers CBT
Oto is a self-administered smartphone program that combines CBT-based audio sessions with
education, mindfulness, and relaxation. It is designed to be used at home,
at the user’s pace, on iOS or Android.
Independent RCTs
Clinical research on Oto
Oto is the subject of two independent university-led randomized controlled trials. Below
are the trials in order of size and rigour, followed by a brief note on the in-house pilot
work that preceded them.
University of Cambridge · Non-inferiority RCT vs. therapist-delivered CBT
In peer review
The DEFINE trial (Digital thErapy For Improved tiNnitus carE Study) is a randomized
non-inferiority study comparing Oto to one-to-one therapist-delivered CBT for tinnitus.
Enrolment of 198 participants completed in 2025. The trial was led by Matt Smith, Assistant Research Professor at the University of Cambridge and Principal Investigator on DEFINE, in collaboration with the Cambridge University
Hospitals NHS Foundation Trust. The trial was partially funded by the UK
government’s innovation agency, Innovate UK, with additional
sponsorship from Oto Health Ltd. The protocol was published open-access in PLOS ONE in January 2024. DEFINE used a decentralized design:
recruitment, interventions, and assessments were conducted remotely, enabling UK-wide
participant involvement without requiring clinic visits. Results are currently undergoing
peer review and will be added here on publication. To our knowledge, DEFINE is the
largest randomized controlled trial of a digital therapy for tinnitus conducted to date.
Flinders University, Australia · Wait-list controlled RCT · CONSORT-adherent
Published
The Flinders University trial is a 96-participant randomized controlled trial of Oto
against a wait-list control over nine months, led by Boaz Mui and the
team at Flinders University’s College of Education, Psychology and Social Work and
Digital Health Research Centre. The trial was CONSORT-adherent and registered with the
Australian New Zealand Clinical Trials Registry (ACTRN12623001138673). The study was partially funded by Flinders University, with additional sponsorship
from Oto Health Ltd.
“Use of Oto demonstrated statistically significant results in reducing tinnitus
severity and distress at 6 months, with effects sustained at 9 months.”
Specifically, the intervention group showed a mean reduction in overall Tinnitus
Functional Index (TFI) score of 9 points compared to the wait-list group at the 6-month
primary endpoint (95% CI [2, 16], p = .006; Cohen’s d = 0.62), with the effect
sustained at 9 months (p = .002, Cohen’s d = 0.54). The full paper is published
open-access in Speech, Language and Hearing (2025).
Note · earlier in-house pilot work (2021). An in-house pilot of an
earlier version of Oto was conducted in 2021. It informed the design of the subsequent
independent academic trials at Cambridge and Flinders. It was not peer-reviewed.
Key takeaways
Oto has been studied in two independent academic randomized controlled trials at the University of Cambridge and Flinders University, enrolling 294 participants in total.
The Flinders RCT was published open-access in Speech, Language and Hearing in 2025. The authors reported statistically significant reductions in tinnitus severity and distress at 6 months, sustained at 9 months (Cohen’s d = 0.62 at 6 months).
The DEFINE trial (Cambridge) compared Oto head-to-head against one-to-one therapist-delivered CBT in a 198-participant non-inferiority, decentralized design. Results are currently in peer review.
DEFINE was co-funded by the UK government’s innovation agency, Innovate UK, alongside Oto Health Ltd.
Both trials were designed, conducted, and analyzed independently by the academic teams at the respective universities.
For clinicians and audiologists
Oto offers a 12-month tinnitus program for independent audiology practices: the Oto
app, provider certification, clinical workflows, and ongoing support.
Two quotes from named, credentialed voices on study design and rigour. Outcome quotes will
appear on DEFINE publication.
Matt Smith
MA, PhD, FRCS (ORL-HNS)
Assistant Research Professor, University of Cambridge · Principal Investigator, DEFINE Trial
DEFINE was designed as a head-to-head, randomized, non-inferiority trial of an at-home digital therapy against therapist-delivered CBT. The design needed to answer rigorously whether digital delivery can hold up against the gold standard. Therapist capacity for tinnitus CBT is extremely limited in most healthcare systems, and the field has needed this kind of evidence.
Dr Evan Davies
Au.D., CH-TM
Head of Clinical Innovation at Oto · Tinnitus and Sound Sensitivity Specialist
Oto sponsors trials and then steps out of the way. The researchers at Cambridge and Flinders designed the studies, ran them, and analyzed the data independently. That’s the kind of evidence base I’d want to point a patient to as a clinician.
Common questions
Frequently asked questions
Has Oto been studied in a clinical trial?01
Yes. Oto has been the subject of two independent university-led randomized controlled trials: a 96-participant trial led by Flinders University (published 2025) and a 198-participant trial led by the University of Cambridge (the DEFINE trial; results in peer review). Trial registrations and publications are listed under "Clinical research on Oto" above.
What is the Tinnitus Functional Index (TFI)?02
The TFI is a validated 25-item questionnaire used to measure tinnitus severity and its impact on daily life. Scores range from 0 to 100, with higher scores indicating greater severity. The TFI is used as a primary outcome measure in the academic trials of Oto and in tinnitus research generally (Meikle et al., 2012).
Who funded the research on Oto?03
Both academic trials of Oto were partially funded by Oto Health Ltd, alongside non-commercial co-funders. The Flinders University trial was co-funded by Flinders University. The Cambridge DEFINE trial was co-funded by the UK government’s innovation agency, Innovate UK. Trial design, conduct, statistical analysis, and reporting were carried out independently by the academic teams at the host universities. Conflict of interest declarations are published in each paper.
Is CBT effective for tinnitus?04
Cognitive behavioral therapy (CBT) is recommended for adults with persistent, bothersome tinnitus by the American Academy of Otolaryngology, Head and Neck Surgery, and as a first-step digital intervention by the UK’s NICE. A 2020 Cochrane systematic review of CBT for tinnitus concluded that CBT may reduce the negative impact of tinnitus on quality of life, with effects considered clinically meaningful.
How is Oto’s research conducted?05
The independent academic trials of Oto (Cambridge DEFINE, Flinders University) follow the international standards expected for clinical research: pre-registered protocols, ethics committee approval, validated outcome measures (TFI), and peer review of results. The DEFINE trial used a decentralized methodology: participants took part from their homes rather than visiting a research clinic.
Can I participate in Oto research?06
Oto runs research studies from time to time. If you are interested in participating in a future study, contact us at support@joinoto.com.
Where can I find the published papers?07
The Flinders University trial is published open-access in Speech, Language and Hearing (2025). The DEFINE trial protocol is published open-access in PLOS ONE (January 2024, DOI: 10.1371/journal.pone.0292562). Direct links are in the "Clinical research on Oto" section above. The DEFINE results paper will be linked here on publication.
Methodology
Our commitment to evidence
Sponsorship and independence
Both academic trials of Oto were partially funded by Oto Health Ltd, alongside non-commercial co-funders. The Flinders University trial was co-funded by Flinders University. The Cambridge DEFINE trial was co-funded by Innovate UK, the UK government’s innovation agency. Trial design, conduct, statistical analysis, and reporting were carried out independently by the academic teams at the host universities. Conflict of interest declarations are published in each paper.
Validated outcome measures
The trials use the Tinnitus Functional Index (TFI), a validated 25-item questionnaire (Meikle et al., 2012) widely used in tinnitus research. A TFI reduction of 13 points or more is generally considered clinically meaningful.
The DEFINE trial used a decentralized design: recruitment, interventions, and assessments were conducted remotely, enabling UK-wide participant involvement without requiring clinic visits. Decentralized designs are increasingly used in clinical research to improve access and reduce participant burden. The full methodology is described in the DEFINE protocol paper (Smith et al., PLOS ONE, 2024).
