Acoustic coordinated reset therapy for tinnitus with perceptually relevant frequency spacing and levels

Peter A Tass,Alexander N Silchenko,Gerald R Popelka

doi:10.1038/s41598-019-49945-w

Peter A Tass, Alexander N Silchenko + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-49945-w

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Journal: Scientific Reports	Publication Date: Sep 20, 2019
Citations: 8	License type: open-access

Affiliation: Stanford University

Abstract

Acoustic coordinated reset (CR) therapy based on neuromodulation and neuroplasticity principles has been proposed for the treatment of tonal tinnitus. The original therapy involved periodic delivery of randomly ordered sequences of four low-level tones centered around the frequency of a tone that matched the tinnitus pitch, fT, with fixed ratios relative to fT and delivered several hours/day over several weeks. Here we transform the original CR tone selection method to a more perceptually-relevant equivalent rectangular bandwidth (ERB) frequency scale, the ERBN-number scale. Specifically, we provide a mathematical model that enables calculation of CR tones that accounts for fT- and hearing loss-related ERB widening and ERB overlaps and gaps of CR tone alignments. Further, the model ensures symmetric CR tone alignments based on modelling studies that indicate the effect is optimal if the CR stimuli are symmetrically spaced relative to the tinnitus-related population of abnormally synchronized cortical neurons to activate the adjacent sub-populations. We also present experimentally testable ERB-based CR tone alignment strategies and explain how to use the ERB-based model in experiments, clinical studies, other types of tinnitus sound treatment such as tailor-made notch music training and limitations of our approach.

Highlights

Tinnitus is the perception of sound in the absence of a sound source external to the person[1,2]
A proof of concept study of acoustic coordinated reset (CR) therapy in 63 patients with chronic tonal tinnitus showed that 12 weeks of acoustic CR treatment, delivered 4–6 h/day, caused significant therapeutic effects compared to baseline
We hypothesize that the relative overlap of the spatial stimulation profiles of neighboring CR tones be identical and symmetrically arranged relative to the profile of the frequency of a tone matched to the pitch of the tinnitus, designated here as fT13,16,34

Summary

Introduction

Tinnitus is the perception of sound in the absence of a sound source external to the person[1,2]. The tinnitus percept is highly variable including self-reported differences in temporal characteristics (constant vs intermittent), perceptual locations (monaural, binaural and central), loudness (low to high) and subjective descriptors (humming, buzzing, ringing, banging, clicking, sea-like, machine-like, and squeaking and many other subjective descriptors)[12] Regardless of these large ranges, the percept can be objectively and reliably characterized by careful psychoacoustic studies of pitch matching, loudness matching and masking using frequency-specific and broad band calibrated external stimuli. Non-invasive acoustic CR stimulation induced long-lasting tinnitus loudness and annoyance reduction effects[20] based on the concept that tonal tinnitus arises primarily from abnormal neural synchrony across a defined array of tonotopically organized neurons[16]. The clinical effects of acoustic CR treatment achieved in the prospective, randomized, single blind, placebo-controlled proof of concept study by Tass et al.[20] were reproduced in two open label studies without sham control group[24,25]

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