Bimodal Electrical-Sound Stimulation and Auditory Training for Chronic Tonal Tinnitus

Condition(s) studied

Investigational drug(s) / intervention(s)

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.

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.

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.

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.

Study summary

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.

Eligibility

Primary outcome measure(s)

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

Trial sites (1)

More University of Dublin, Trinity College trials in Ireland