Exploiting the Potential of Neural Attentional Control to Overcome Hearing Impairment

Not Applicable

Recruiting

• Conditions: Hearing Loss; Attention Impaired; Tinnitus
• Interventions: Device: sham - transcranial alternating current stimulation; Device: tACS - transcranial alternating current stimulation; Device: NF - Neurofeedback

• Registration Number: NCT05513352
• Lead Sponsor: University of Zurich

Brief Summary

This study will improve the understanding of the cerebral mechanisms that underlie the control of auditory selective attention and evaluate the potential of neuromodulation to enhance neural attention control as a possible way to overcome hearing impairment.

First, electroencephalography (EEG) will be applied to identify neural marker of auditory attention in individuals with hearing loss (HL), tinnitus (TI) and normal hearing (NH). Afterwards, the importance of the identified markers for attention control will be tested using non-invasive transcranial alternating current stimulation (tACS) and neurofeedback (NF).

Detailed Description

Hearing loss and associated conditions such as tinnitus are the fourth highest cause of disability worldwide, with estimated annual cost of over 750 billion dollars. Due to the rise and ageing of the global population, the number of people with hearing impairment is growing at a rapid pace. Besides, the incidence of noise induced hearing impairment is also increasing in younger populations. A common complaint of hearing impaired individuals is the significant decline of speech comprehension under challenging listening conditions. These situations typically include reverberations, background noise or multiple speakers and they require the listener to direct attention selectively to a target sound source (e.g. the interlocutor) and to suppress distracting sounds in the background (e.g. from not attended speakers).

Auditory prostheses with pinna-imitating microphones can improve the localization of a target sound source through the sensory enhancement of spatial cues in the acoustic signal. However, the benefit of additional sensory information is limited due of the missing implementation of attention control that would permit the selective amplification of the target sound source and the suppression of irrelevant distracting noise.

The question of how the brain instantiates attentional filter mechanisms that control target amplification and distractor suppression has drawn a lot of interest in the field of cognitive neuroscience. Neural markers of auditory attention such as lateralized oscillatory brain activity in the alpha frequency band (\~8-12Hz) and the enhanced neural tracking of attended of attended speech have been linked to the top-down control of attention. However, the interrelationship between these neural markers is still underexplored. Further, the functional role of alpha band oscillations in auditory attention is underspecified as they could potentially implement target enhancement and distractor suppression. Together, this limits the understanding of the neuro-cognitive basis of attention.

The proposed project aims to address this problem by improving the investigators understanding of the cerebral mechanisms that underlie the control of auditory selective attention. The outlined research project will test the hypothesis that individuals with hearing impairment have deficits in auditory distractor inhibition that are reflected by ineffective neural suppression of irrelevant information. This hypothesis will be examined in three different lines of research. In research line 1, I will test a new framework in individuals who suffer from sensorineural hearing loss or tinnitus that allows to dissociate target selection and distractor suppression at the neural level based on electroencephalography (EEG) recordings. In research lines 2-3, I will then evaluate the potential of electric brain stimulation and neurofeedback to enhance auditory distractor suppression.The results of this project will have theoretical implications for current models of auditory attention and speech comprehension by specifying the functional role of oscillatory brain activity in normal hearing individual and hearing impaired populations. Beyond, this research will contribute new insights how the control of auditory selective attention could be implemented in a brain-computer interface.

Study Timeline

• Study First Submitted: 2022-08-17
• Study First Submitted QC: 2022-08-23
• Study First Posted: 2022-08-24
• Status Verified: 2023-11
• Study Start: 2023-11-01
• Last Update Submitted: 2023-11-30
• Last Update Posted: 2023-12-07
• Primary Completion: 2026-04
• Study Completion: 2026-04

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 275

Inclusion Criteria

• Age: 18-35 / 55-75
• German as first language
• Normal or corrected to normal vision
• Right-handed
• Normal hearing, hearing impairment or tinnitus (see specified inclusion)
• Normal hearing: ≤20 decibel (dB) hearing level (HL) at frequencies from 250 Hz to 8,000 Hz for both ears.

Specified inclusion for Experiment 1, 2, 3 & 4:

• Hearing loss:
• bilateral symmetrical sensorineural hearing loss
• pure tone thresholds of ≥25 dB HL at one or more frequencies between 250 Hz and 8,000 Hz and differences in thresholds across the two ears of ≤20 dB at every frequency.
• Tinnitus:
• Persistent chronic tinnitus with duration of more than 3 months
• Tinnitus with a Tinnitus Handicap Inventory Grade 2 to 4 (18-76 points)

Exclusion Criteria

• Non-symmetrical hearing loss

• Raised bi- or multilingually (second language acquired earlier than 6 years of age)

• Women who are currently pregnant or breastfeeding

• History of brain injury or any neurological disorder (y/n)

  • For example, stroke, traumatic brain injury, brain surgery, epilepsy etc.

• Dyslexia

• History of psychiatric disorder

• Recent recreational drug consumption

• Known or suspected drug or alcohol abuse

• Medication with cognitive side effects (e.g., psychoactive medications or sleeping pills)

• Metallic implants in the head region (excluding fixed braces and tooth fillings)

• Any implanted medical device (e.g., cardiac pacemakers)

• Previous enrolment in one of the experiments comprising the main investigational plan

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Experiment 3 - normal hearing (sham) - AAT	sham - transcranial alternating current stimulation	The subjects assigned to the normal hearing group will undertake 20min sham stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) sham brain stimulation, and (3) post-stimulation. AAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 3 - hearing impaired (sham) - AAT	sham - transcranial alternating current stimulation	The subjects assigned to the hearing impaired group will undertake 20min sham stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) sham brain stimulation, and (3) post-stimulation. AAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 3 - tinnitus (sham) - AAT	sham - transcranial alternating current stimulation	The subjects assigned to the tinnitus group will undertake 20min sham stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) sham brain stimulation, and (3) post-stimulation. AAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 3 - normal hearing (tACS) - AAT	tACS - transcranial alternating current stimulation	The subjects assigned to the normal hearing group will undertake 20min tACS stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) brain stimulation, and (3) post-stimulation. AAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 3 - tinnitus (tACS) - AAT	tACS - transcranial alternating current stimulation	The subjects assigned to the tinnitus group will undertake 20min tACS stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) brain stimulation, and (3) post-stimulation. AAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 4 - normal hearing (tACS) - SAT	tACS - transcranial alternating current stimulation	The subjects assigned to the normal hearing group will undertake 20min tACS stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) brain stimulation, and (3) post-stimulation. SAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 3 - hearing impaired (tACS) - AAT	tACS - transcranial alternating current stimulation	The subjects assigned to the hearing impaired group will undertake 20min tACS stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) brain stimulation, and (3) post-stimulation. AAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 4 - normal hearing (sham) - SAT	sham - transcranial alternating current stimulation	The subjects assigned to the normal hearing group will undertake 20min sham stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) sham brain stimulation, and (3) post-stimulation. SAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 4 - hearing impaired (tACS) - SAT	tACS - transcranial alternating current stimulation	The subjects assigned to the hearing impaired group will undertake 20min tACS stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) brain stimulation, and (3) post-stimulation. SAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 4 - hearing impaired (sham) - SAT	sham - transcranial alternating current stimulation	The subjects assigned to the hearing impaired group will undertake 20min sham stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) sham brain stimulation, and (3) post-stimulation. SAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 4 - tinnitus (tACS) - SAT	tACS - transcranial alternating current stimulation	The subjects assigned to the tinnitus group will undertake 20min tACS stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) brain stimulation, and (3) post-stimulation. SAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 4 - tinnitus (sham) - SAT	sham - transcranial alternating current stimulation	The subjects assigned to the tinnitus group will undertake 20min sham stimulation applied over the temporo-parietal cortex. Each session will include the following three phases: (1) pre-stimulation baseline, (2) sham brain stimulation, and (3) post-stimulation. SAT will be conducted in each phase and concurrent EEG will be recorded.
Experiment 5 - normal hearing (NF right) - AAT	NF - Neurofeedback	Each participant of the normal hearing group will undergo the neurofeedback training in which the participants learn to increase alpha power in the right relative to the left parietal cortex. Before and after the NF training, participants will perform the AAT and concurrent EEG will be recorded.
Experiment 5 - normal hearing (NF left) - AAT	NF - Neurofeedback	Each participant of the normal hearing group will undergo the neurofeedback training in which the participants learn to increase alpha power in the left relative to the right parietal cortex. Before and after the NF training, participants will perform the AAT and concurrent EEG will be recorded.

Primary Outcome Measures

Name	Time	Method
Experiment 1 - EEG	One study session of 4 hours and 40 minutes	The primary endpoint is the comparison of neural alpha power lateralization in response to target selection and distractor suppression in individuals with HL, TI and a NH control group.
Experiment 4 - SAT	One study session of 4 hours and 40 minutes	The primary endpoint is the comparison of speech comprehension performance between tACS over the left temporo-parietal cortex, and an ineffective sham stimulation during and after stimulation relative to pre-stimulation baseline.
Experiment 2 - EEG	One study session of 4 hours and 40 minutes	The primary endpoint is the comparison of the neural tracking of the amplitude envelope of speech between individuals with HL, TI and NH.
Experiment 5 - EEG 1	two sessions of 4 hours and 40 minutes on separate days	The primary endpoint is the comparison of participants' ability to control alpha power lateralization index during training between training conditions (left NF training vs. right NF training).
Experiment 3 - AAT	One study session of 4 hours and 40 minutes	The primary endpoint is the comparison of auditory attention performance between tACS over the left temporo-parietal cortex, and an ineffective sham stimulation during and after stimulation relative to pre-stimulation baseline.

Secondary Outcome Measures

Name	Time	Method
Experiment 4 - EEG 1	One study session of 4 hours and 40 minutes	Comparison of lateralization index between stimulation conditions (tACS vs. sham)
Experiment 3 - EEG 2	One study session of 4 hours and 40 minutes	Comparison of event-related responses to target and distractor stimuli between stimulation conditions (tACS vs. sham)
Experiment 4 - EEG 2	One study session of 4 hours and 40 minutes	Comparison between neural tracking of target and distracting speech between stimulation conditions (tACS vs. sham)
Experiment 5 - EEG 2	two sessions of 4 hours and 40 minutes on separate days	Comparison of auditory evoked responses to probes presented ipsilateral vs. contralateral to the trained hemisphere
Experiment 1 - AAT	One study session of 4 hours and 40 minutes	To test whether alpha power lateralization during distractor suppression and target selection predicts AAT task performance in HL, TI, and NH individuals.
Experiment 2 - SAT	One study session of 4 hours and 40 minutes	The relation between neural speech tracking and speech comprehension performance in NH, HL, and TI
Experiment 3 - EEG 1	One study session of 4 hours and 40 minutes	Comparison of neural alpha power lateralization between stimulation conditions (tACS vs. sham)
Experiment 5 - EEG 3	two sessions of 4 hours and 40 minutes on separate days	Comparison of changes in target and distractor related alpha power lateralization between NF training conditions (left NF training vs. right NF training) pre- vs post NF Training
Experiment 5 - AAT	two sessions of 4 hours and 40 minutes on separate days	Comparison of auditory attention performance across training conditions (left NF training vs. right NF training)

Trial Locations

Locations (1)

University of Zurich; 🇨🇭 Zürich, Switzerland