The Longer, the Better? Investigating the Effect of Prolonged Acoustic Stimulation on Brief Acoustic Tinnitus Suppression

The study comprised three experimental acoustic stimulation sessions. In session one, audiometric and tinnitometric assessments were conducted, followed by stimulation with three noise stimuli: white noise (WN), white noise with a bandstop filter (WN_BS), and white noise with a bandpass filter (WN_BP), each implemented with a one-octave filter around the individual tinnitus frequency (ITF). Session two (3-14 days later) included five pure tone stimuli: a tone at the ITF, two amplitude-modulated tones at the ITF (10 Hz, 23 Hz), and two amplitude-modulated tones three octaves below the ITF (10 Hz, 23 Hz). Stimuli were presented diotically for 3 minutes with 1000 ms fade-in/out, separated by 6-minute breaks. Participants experiencing brief acoustic tinnitus suppression (BATS) in session one or two completed a third session, in which the stimulus inducing the strongest suppression was applied for 20 minutes. Tinnitus loudness was rated immediately after stimulation using a numeric rating scale (0-110% of baseline loudness) at multiple time points up to 180 seconds, and up to 600 seconds after the 20-minute stimulation to capture prolonged suppression.

Inclusion criteria

• Diagnosis of chronic tinnitus, defined as a tinnitus duration of at least 6 months
• Written informed consent: The patient must be able to understand the study information, comply with the required examinations and appointments, and provide written informed consent
• Male or female patients, aged 18-75 years

Exclusion criteria

• Objective tinnitus
• Tinnitus below 1000 Hz
• Presence of Menière's disease, otosclerosis, acoustic neuroma, or other clearly identifiable and treatable causes of tinnitus
• Initiation of other tinnitus treatments within the last three months prior to study entry
• Lack of informed consent
• Oropharyngeal infection
• Presence of clinically relevant severe internal, neurological, or psychiatric disorders
• Drug, medication, or alcohol abuse within 12 weeks prior to study entry
• Any other condition that, in the opinion of the investigator, makes participation in the study unsuitable
• Hyperacusis
• Current pharmacological treatment with psychoactive substances (e.g., antidepressants, anticonvulsants)