Residual Inhibition of 40 Hz Burst Sound in Tinnitus Patients

Neural and Clinical Effects of 40 Hz Burst Stimulation in Tinnitus: a Four-phase Self-controlled Study

Tinnitus affects 10-15% of adults and is frequently associated with impaired quality of life, anxiety, and sleep disturbance. Conventional sound therapies based on continuous masking provide inconsistent and short-lived relief, and the neural mechanisms underlying residual inhibition (RI) remain unclear.

This study aims to determine whether 40 Hz burst stimulation with high-frequency carriers can achieve longer-lasting RI than continuous sound, and to explore its underlying neural mechanisms using EEG.

Residual inhibition (RI) refers to the temporary reduction or disappearance of tinnitus following sound stimulation and provides an important clue for identifying patients who may benefit from acoustic therapy. However, the effects of different sound stimulation strategies on RI remain poorly understood.

This study evaluates whether 40 Hz burst-modulated sound achieves stronger and longer RI compared with conventional continuous stimulation. The trial follows a four-phase design:

Phase 1: Exploratory testing of burst versus continuous tones at different frequencies.

Phase 2: Large-scale validation in 265 patients. Phase 3: Development of a personalized stimulation protocol using adaptive spectral optimization.

Phase 4: EEG investigation of neural mechanisms, focusing on gamma oscillations and functional connectivity changes.

The primary outcomes are the strength and duration of tinnitus suppression. Secondary outcomes include EEG markers such as γ-band power spectral density and phase-locking value.

By combining behavioral and neurophysiological measures, this study aims to establish 40 Hz burst stimulation as a novel rhythm-based sound therapy and to provide mechanistic insights that may enable more effective, personalized tinnitus management.

Inclusion Criteria:

1. Diagnosed with subjective tinnitus;
2. Chronic tinnitus: tinnitus course ≥ 1 month;
3. Normal middle ear function;
4. The average hearing threshold (defined as mean of 0.5, 1, 2, and 4 kHz) of the unaffected ear < 60 dB;
5. Tinnitus can be heard under normal circumstances.
6. Subjects are able to understand the purpose of the study, volunteer to participate and cooperate with the instructors to complete the experiment, and be willing to sign the informed consent.

Exclusion Criteria:

1. Acute phase tinnitus;
2. Fluctuating tinnitus loudness;
3. Severe psychiatric disorders;
4. Inability to complete tinnitus testing;
5. Fluctuating or retrocochlear hearing loss;
6. Conductive hearing loss;
7. Currently participating in other research projects that may affect tinnitus;
8. Subjects who are not considered suitable for this clinical trial by the researchers.