Bimodal Electrical-Sound Stimulation and Auditory Training for Chronic Tonal Tinnitus (NITESGON-ADT)

Non-Invasively Re-Training the Tinnitus Brain Using Bimodal Electrical-Sound Stimulation (NITESGON-ADT): Protocol for a Prospective, Double-Blind, Randomised Controlled Trial

This study tests whether pairing non-invasive stimulation of the greater occipital nerve (NITESGON) with an attentionally demanding auditory frequency discrimination training task reduces tinnitus loudness and tinnitus-related distress. One hundred adults with chronic tonal tinnitus will be randomised to one of four groups in a 2×2 factorial design: real versus sham NITESGON and active versus passive listening during auditory stimulation. Participants complete eight sessions across four weeks, with outcomes assessed at baseline, end of treatment, 28 days post-treatment, and 6 months post-treatment.

Study Overview

• Status: Recruiting
• Conditions: Tinnitus, Subjective; Tinnitus; Chronic Tinnitus
• Intervention / Treatment: Device: Real NITESGON; Behavioral: Active Listening; Behavioral: Passive Listening (Control); Device: Sham NITESGON

Detailed Description

This is a single-centre, prospective, double-blind, placebo-controlled, 2×2 factorial randomised controlled trial conducted at Trinity College Dublin. The intervention combines transcutaneous electrical stimulation targeting the greater occipital nerve (NITESGON) with auditory stimulation delivered during a structured training paradigm. The two between-subjects factors are stimulation condition (real NITESGON vs sham NITESGON) and listening condition (active listening: auditory frequency discrimination training vs passive listening: visual distractor task while auditory stimuli are presented). One hundred adults with chronic tonal tinnitus will be randomised 1:1:1:1 to one of four arms. Participants complete eight sessions (two per week for four weeks). Primary outcomes-tinnitus loudness (VAS 0-100), tinnitus-related functional impact (TFI 0-100), and tinnitus handicap (THI 0-100)-and secondary outcomes are assessed at baseline (T0), end of treatment (T1), 28 days after treatment completion (T2), and 6 months after treatment completion (T3). Secondary outcomes include tinnitus psychoacoustics, extended high-frequency audiometry, speech-in-noise performance, EEG (resting-state and auditory oddball), autonomic/biomarker measures (pupillometry, heart rate, saliva), patient global impression of change, quality of life, and safety/blinding assessments.

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Anusha Mohan, PhD; Email: anusha.mohan@tcd.ie
• Study Contact Backup: Name: Sven Vanneste, PhD; Phone Number: +353 87 470 2835.; Email: sven.vanneste@tcd.ie

Study Locations

• Ireland
  • Dublin
    • Dublin, Dublin, Ireland, D02
      • Recruiting
      • Trinity College Institute of Neuroscience (TCIN)
      • Contact: Fabian Broecker; Phone Number: +353 087 470 2835.; Email: broeckef@tcd.ie

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults aged 18-80 years
• Continuous subjective tinnitus for >3 months and ≤5 years
• Predominantly tonal tinnitus (unilateral or bilateral)
• Screening THI score 28-76
• Minimum Masking Level (MML) 20-80 dB HL
• No prior tinnitus neuromodulation treatment
• Able to comply with eight sessions over four weeks and follow-up assessments

Exclusion Criteria:

• Objective tinnitus or predominantly somatic tinnitus
• Pulsatile tinnitus
• Evidence of conductive hearing loss (abnormal otoscopy or tympanometry)
• Pure-tone audiometry exclusions: >40 dB HL at any frequency 250 Hz-1 kHz OR >80 dB HL at any frequency 2-8 kHz in either ear
• Hearing aid use initiated within the past 90 days
• Active implantable medical device (e.g., pacemaker, DBS, cochlear implant)
• LDL <30 dB SL at 500 Hz in either ear
• Diagnosis of temporomandibular joint disorder or occipital neuralgia
• Severe anxiety (STAI >120/160)
• Cognitive impairment (MMSE <25)
• Severe depressive symptoms (BDI ≥30)
• Diagnosis of Menière's disease
• Current pregnancy
• Involvement in medicolegal cases
• History of auditory hallucinations
• Current prescription of central nervous system drugs likely to alter neuromodulatory function (e.g., noradrenergic, dopaminergic, serotonergic, benzodiazepine, cholinergic, or other psychoactive medications)
• Currently enrolled in another interventional study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Factorial Assignment
• Masking: Double

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Real Stimulation + Active Listening (ADT); Real stimulation delivered during active auditory frequency discrimination training.	Device: Real NITESGON; Real NITESGON is delivered transcutaneously via two saline-soaked sponge electrodes (35 cm² each) positioned bilaterally over the C2 dermatomes to target the greater occipital nerve. Stimulation consists of a 20 Hz sinusoidal current at 1.5 mA peak-to-peak, ramped up over 30 seconds and ramped down over 5 seconds. It is administered concurrently with the task for ~45 minutes per session, across eight sessions (2/week) over 4 weeks.; Behavioral: Active Listening; ADT is delivered using a three-interval, three-alternative forced-choice (3I-3AFC) frequency discrimination task. Standard tone frequencies are individually selected using ERB/critical-band spacing, centered one octave below each participant's dominant tinnitus pitch and extending to lower frequencies; the highest standard is kept below the tinnitus pitch region. Tones are presented binaurally via headphones, with presentation levels calibrated to individual audiometric thresholds and matched for equal SPL in both ears.; Other Names: Auditory frequency discrimination training (ADT)
Active Comparator: Real Stimulation + Passive Listening; Real stimulation delivered while participants perform a visual distractor task and are instructed to ignore auditory stimuli.	Device: Real NITESGON; Real NITESGON is delivered transcutaneously via two saline-soaked sponge electrodes (35 cm² each) positioned bilaterally over the C2 dermatomes to target the greater occipital nerve. Stimulation consists of a 20 Hz sinusoidal current at 1.5 mA peak-to-peak, ramped up over 30 seconds and ramped down over 5 seconds. It is administered concurrently with the task for ~45 minutes per session, across eight sessions (2/week) over 4 weeks.; Behavioral: Passive Listening (Control); VisDT uses a three-interval, three-alternative forced-choice (3I-3AFC) paradigm with Gabor patches (sinusoidal gratings windowed by a Gaussian envelope) of fixed spatial frequency (6 cycles/degree) and fixed spatial spread; on each trial, one interval contains an orientation deviant relative to the standard. During VisDT, participants attend to the visual task while concurrent binaural tones are presented passively using a predetermined, non-adaptive schedule. Auditory tones are individually calibrated to audiometric thresholds and drawn from ERB-spaced frequencies centered one octave below the dominant tinnitus pitch and extending to lower frequencies, with the highest frequency kept below the tinnitus pitch region.; Other Names: Visual distractor task (VisDT)
Sham Comparator: Sham Stimulation + Active Listening (ADT); Sham stimulation delivered during active auditory frequency discrimination training.	Behavioral: Active Listening; ADT is delivered using a three-interval, three-alternative forced-choice (3I-3AFC) frequency discrimination task. Standard tone frequencies are individually selected using ERB/critical-band spacing, centered one octave below each participant's dominant tinnitus pitch and extending to lower frequencies; the highest standard is kept below the tinnitus pitch region. Tones are presented binaurally via headphones, with presentation levels calibrated to individual audiometric thresholds and matched for equal SPL in both ears.; Other Names: Auditory frequency discrimination training (ADT); Device: Sham NITESGON; Sham NITESGON is delivered using two saline-soaked sponge electrodes (35 cm² each) positioned bilaterally over the C2 dermatomes. The sham condition mimics real stimulation sensations via a 30-second ramp-up followed by a brief ramp-down, with no sustained current thereafter. Sham is administered concurrently with the task for ~45 minutes per session, across eight sessions (2/week) over 4 weeks.
Sham Comparator: Sham Stimulation + Passive Listening; Sham stimulation delivered while participants perform a visual distractor task and are instructed to ignore auditory stimuli.	Behavioral: Passive Listening (Control); VisDT uses a three-interval, three-alternative forced-choice (3I-3AFC) paradigm with Gabor patches (sinusoidal gratings windowed by a Gaussian envelope) of fixed spatial frequency (6 cycles/degree) and fixed spatial spread; on each trial, one interval contains an orientation deviant relative to the standard. During VisDT, participants attend to the visual task while concurrent binaural tones are presented passively using a predetermined, non-adaptive schedule. Auditory tones are individually calibrated to audiometric thresholds and drawn from ERB-spaced frequencies centered one octave below the dominant tinnitus pitch and extending to lower frequencies, with the highest frequency kept below the tinnitus pitch region.; Other Names: Visual distractor task (VisDT); Device: Sham NITESGON; Sham NITESGON is delivered using two saline-soaked sponge electrodes (35 cm² each) positioned bilaterally over the C2 dermatomes. The sham condition mimics real stimulation sensations via a 30-second ramp-up followed by a brief ramp-down, with no sustained current thereafter. Sham is administered concurrently with the task for ~45 minutes per session, across eight sessions (2/week) over 4 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Tinnitus Loudness (Visual Analogue Scale, VAS 0-100)	0-100 mm VAS anchored from "not audible" to "extremely loud"; higher scores indicate greater perceived tinnitus loudness.	Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Tinnitus Functional Index (TFI, 0-100)	25-item self-report measure of tinnitus-related functional impact; total score 0-100, higher scores indicate greater impairment.	Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Tinnitus Handicap Inventory (THI, 0-100)	25-item measure of tinnitus-related handicap; total score 0-100, higher scores indicate greater handicap.	Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Audiometry (Extended High-Frequency Thresholds up to 13 kHz)	Air-conduction pure-tone audiometry thresholds will be measured from 250 Hz up to 13 kHz (extended high-frequency audiometry) to characterise hearing status and support calibration of stimulus sensation levels.	Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Speech-in-Noise Performance (e.g., QuickSIN)	Speech perception in noise will be assessed using a standardised speech-in-noise test administered in a controlled environment.	Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Patient Global Impression of Change (PGIC)	Participant-rated global change since baseline using the Patient Global Impression of Change (PGIC) scale (-3 = very much worse to +3 = very much improved; higher scores indicate greater improvement).	End of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Quality of Life (World Health Organization Quality of Life-BREF questionnaire)	Quality of life assessed using the World Health Organization Quality of Life-BREF (WHOQOL-BREF), yielding domain scores and an overall score (0-100; higher scores indicate better quality of life).	Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Adverse Events (Stimulation Side-Effects Questionnaire)	Stimulation tolerability assessed each visit using a Stimulation Side-Effects Questionnaire recording presence and severity of side effects (e.g., tingling, itching, headache) rated on a numeric severity scale (0-10; higher scores indicate worse side effects), plus event frequency.	Up to 4 weeks (Sessions 1-8)
Tinnitus Pitch Matching	Dominant tinnitus pitch estimated by psychoacoustic pitch matching and recorded as frequency in hertz (Hz).	Baseline, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Tinnitus Loudness Matching and Discomfort Levels	Loudness matching and discomfort levels: Tinnitus loudness matching recorded in decibels sensation level (dB SL; dB above audiometric threshold) at the matched frequency, and loudness discomfort levels recorded in decibels sensation level (dB SL; dB above threshold) at tested frequencies.	Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Minimum Masking Level (MML)	Broadband noise level required to fully mask tinnitus, recorded in decibels hearing level (dB HL).	Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.
Resting-State EEG Spectral Power (Eyes Closed)	Resting-state eyes-closed electroencephalography (EEG) spectral power averaged within prespecified frequency bands and electrode/network regions, reported in decibels (dB); higher values indicate greater spectral power.	Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.
Resting-State EEG Functional Connectivity (Eyes Closed)	Resting-state eyes-closed EEG functional connectivity within prespecified networks, quantified as phase-locking value (PLV; unitless, 0-1); higher values indicate stronger phase synchronization.	Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.
Auditory Oddball Task-Evoked Response Amplitude	Auditory oddball event-related potential (ERP) amplitude (e.g., P300) averaged over prespecified electrodes/time windows, reported in microvolts (µV); higher absolute amplitude indicates larger task-evoked response.	Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.
Auditory Oddball Task-Evoked Response Latency	Auditory oddball ERP component latency (e.g., P300 peak latency) within prespecified time windows, reported in milliseconds (ms); lower values indicate faster evoked responses.	Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.
Pupillometry	Task-related pupil diameter during pupillometry, summarized as mean (or peak) pupil size change from baseline, reported in millimeters (mm); larger values indicate greater pupil dilation.	Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.
Heart Rate	Electrocardiography (ECG)-derived heart rate, reported in beats per minute (bpm); higher values indicate faster heart rate.	Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.
Saliva Biomarkers	Concentration of prespecified salivary biomarkers of arousal/neuromodulatory engagement, reported in nanograms per milliliter (ng/mL) (or assay-specific units); higher values indicate higher biomarker concentration.	Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.

Collaborators and Investigators

• Sponsor: University of Dublin, Trinity College

Study record dates

Study Major Dates

• Study Start (Actual): January 30, 2026
• Primary Completion (Estimated): September 30, 2028
• Study Completion (Estimated): January 30, 2029

Study Registration Dates

• First Submitted: January 23, 2026
• First Submitted That Met QC Criteria: January 30, 2026
• First Posted (Actual): February 6, 2026

Study Record Updates

• Last Update Posted (Actual): April 3, 2026
• Last Update Submitted That Met QC Criteria: April 2, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Tinnitus
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Otorhinolaryngologic Diseases; Sensation Disorders; Ear Diseases; Hearing Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Tinnitus
• Other Study ID Numbers: NITESGON-SPREC102020-46; DRG2332 (Other Grant/Funding Number: RNID)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No