Physiological markers of stress reaction and tinnitus sound therapy using hearables

Abstract

Tinnitus is an auditory sensation that is perceived when no external sound is present. In some cases, this perception coincides with severe suffering and therefore, tinnitus is often evaluated as a psychological stressor. Tinnitus-related distress has been associated with increased levels of cortisol and elevated levels of sympathetic tonus. For the current study, the primary hypothesis was that sound therapy will reduce tinnitus perception and various physiological measures of stress. A secondary hypothesis was that a self-selected nature sound would reduce physiological markers of stress more than a broadband sound. The objective markers chosen to demonstrate these effects were blood pressure, heart rate and salivary cortisol and cortisone concentrations. Twenty-one participants with constant bothersome tinnitus underwent an audiological assessment and completed the Hospital Anxiety and Depression Scale, the Tinnitus Sample Case History Questionnaire and the Tinnitus Functional Index. Measurements of blood pressure, heart rate and saliva sampling along with tinnitus perception using the Tinnitus Severity Numeric Scale were carried out three times, prior to and after broadband noise and a self-selected nature sound, for a duration of thirty-minutes each. Findings revealed significant reductions in blood pressure measurements following broadband noise. None of the other stress measures demonstrated a statistically significant change. Both broadband noise and nature sound stimuli elicited significant improvements in overall problem, loudness, discomfort and annoyance ratings of tinnitus. Nature sounds also resulted in a significant reduction in tinnitus unpleasantness rating scores. While both sound types had a positive impact on many dimensions of tinnitus, only the nature sound reduced tinnitus unpleasantness. The reduction in unpleasantness observed with the nature sound was not accompanied by a significant change in any physiological measure. The broadband noise was associated with a reduction in blood pressure. These results are consistent with a complex interaction between sound and tinnitus and suggest a multifactorial basis to sound therapy.