Fatigue and Hearing Performance of Healthy Volunteers Acutely Exposed to Occupational Noise ( FATIGAUDIT) (FATIGAUDIT)

Fatigue and Hearing Performance in Healthy, Normal-hearing Volunteers Acutely Exposed to Occupational Noise Not Requiring Personal Protection. FATIGAUDIT

Occupational noise exposure is regulated by law, and protective measures are applied if the noise level exceeds 90 dB(A). The inferior exposure levels can cause an auditory fatigue which is defined as temporary and reversible hearing loss. Its mechanisms, however, remain largely underexplored with recent animal data suggesting that the long-term exposure (over several weeks) to noise above 85 dB Sound Pressure Level (SPL) may provoke a permanent damage to hearing. Furthermore, there is also a lack of research on cognitive and attentional repercussions of this phenomenon. Yet, this information could be important to prevent work-related errors and accidents. Lastly, although silent breaks (noise-free resting periods) throughout a day of work are preconized to limit the noise exposure, their effect on auditory fatigue has never been demonstrated.

Being a part of a larger project involving fundamental researchers (animal experimentation) and occupational health specialists (investigations at the workplace), this study aims:

• to evaluate how auditory fatigue caused by acute noise exposure in doses tolerated by law impacts auditory and cognitive performances in humans
• to determine the effect of silent breaks proposed by occupational legislation on cognitive functioning
• to issue new recommendations for the protection of workers exposed to noise

Study Overview

• Status: Not yet recruiting
• Conditions: Noise Exposure; Auditory Fatigue; D001305; Environmental Noise; Auditory Performance
• Intervention / Treatment: Other: 2h30 of noise exposure at 85 dB(A); Other: 2 noise exposures of 66 minutes; Other: 10 noise exposure cycles; Other: No noise exposure

Detailed Description

Study rationale:

Individuals routinely endure daily noise exposure related to transportation as well as occupational and recreational (portable music players, video games, concerts) activities. European and United States regulations have limited occupational noise exposure to 85 dB(A) (A-weighting - the sound pressure level filtered appropriately to the human audiogram) based on an 8h working day. This level is commonly encountered in the manufacturing, construction, and music industries, while noise levels are constantly increasing in the tertiary sector.

Overall, 13% of people are exposed to a cumulative daily dose of noise equal to or exceeding 85 dB(A) approved by law. This is not without a harm: excessive noise exposure rises stress levels, induces physical tiredness and causes headaches leading to increased workplace accident rates. It can also stimulate aggression and other antisocial behaviours.

Importantly, a daily noise exposure of 85 dB(A) is responsible for "auditory fatigue" - a complex phenomenon correlated to a temporary elevation of hearing thresholds or TTS (temporary threshold shift). According to recent investigations, daily TTS can reach 5 dB elevations (i.e. a 68% decrease in sound intensity perceived) in factory workers and sound engineers at the end of every single workday.

Auditory fatigue has received little attention in the scientific literature because TTS is considered fully reversible and therefore inoffensive. This complacency might be misplaced: auditory fatigue repeated throughout a career may contribute to:

• the permanent hearing loss experienced by 10-15% of people exposed to occupational noise below the legal exposure limit
• the increased rate of chronic auditory disorders such as tinnitus (a perception of phantom sounds) or hyperacusis (a reduced tolerance for moderate sound levels) in professional musicians and noise-exposed workers
• a decrease in auditory performance (e.g. speech-in-noise or frequency discrimination), a heavier cognitive load or an adaptive modification of brain circuits under the prolonged sensory constraints of noise masking and degraded hearing sensitivity

Recent rodent studies show that a TTS can have damaging consequences on sensorineural inner ear structures despite a long-term recovery of hearing thresholds. For instance, weeks to months of continuous exposure at 85 dB Sound Pressure Level (SPL) may induce ultrastructural abnormalities within the cochlea, loss of synaptic ribbons in sensory inner hair cells, an amplitude decrease of auditory nerve activity and delayed degeneration of auditory nerve fibres. These symptoms, referred to as synaptopathy, disrupt the signal transmission. This could potentially explain why some subjects experience poor speech perception in noise despite normal auditory thresholds.

Whether auditory fatigue, i.e. the daily noise-induced TTS after 8 hours at 85 dB(A), involves one of the above insults (or other ones) remains unknown. The possibility of preventing auditory fatigue, for example by rest periods, also depends on the mechanisms involved and their kinetics. Due to its fast recovery at the scale of minutes or hours, it is scientifically and technically challenging to detect auditory fatigue and then establish its relationship with immediate- and long-term consequences on the molecular, functional, and perceptive levels. Nevertheless, auditory fatigue is an important and neglected public and occupational health issue.

The aim of the FATIGAUDIT study is:

• to better evaluate the temporary changes in auditory and cognitive performances of healthy volunteers after an acute noise exposure of 85 dB(A) for 2 and a half hours (the sound level in a noisy canteen or during choir rehearsal for a duration well below the legal threshold of 8 hours)
• to determine whether the introduction of silent breaks limits these temporary changes and reduces a cognitive load

From an ethical point of view, it is not possible to propose prolonged and/or chronic exposure to this type of noise as it might damage hearing irreversibly.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Michel MONDAIN, Pr; Phone Number: +33 467336893; Email: m-mondain@chu-montpellier.fr
• Study Contact Backup: Name: Akil KADERBAY, Dr

Study Locations

• France
  • Montpellier, France
    • CHU Gui de Chauliac, ENT & Head and Neck Surgery Department

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Healthy subjects aged between 18 and 35
• With normal pure-tone audiometry data (air and bone conductions) on both ears: hearing thresholds ≤20 dB HL for each frequency tested - 125, 250, 500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz
• With normal Speech-in-noise test (the speech reception threshold (SRT) at which 50% recognition of the speech stimuli presented is achieved must be 3 dB higher than the standard test value established in subjects with normal hearing)
• Without history of excessive noise exposure (1-MINUTE NOISE SCREEN ≤4)

Exclusion Criteria:

• History of sudden deafness or tinnitus lasting more than 48 hours
• Conditions likely to affect hearing (tumours of the ear or base of the skull, etc.)
• History of unresolved chronic otitis
• Work in a noisy environment requiring workplace soundproofing or the use of personal protective equipment
• Migraine with or without aura or tension-type headaches (International Headache Society (IHS) classification)
• Pregnant or breastfeeding women or women of childbearing age not using contraception
• Participation in another interventional clinical trial
• A person whose physical and/or psychological health is severely impaired
• Individuals deprived of their legal capacity, or under guardianship or trusteeship
• Persons deprived of liberty (by judicial or administrative decision)
• Not affiliated to a French social security system or not a beneficiary of this system
• Absence written informed consent to participate in the study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group 1 : 2H30 of non-stop noise exposure; Group 1 (n=10) will be exposed to 85 dB(A) for 2h30 without any interruption of noise exposure	Other: 2h30 of noise exposure at 85 dB(A); 2h30 of uninterrupted noise exposure at 85 dB(A)
Experimental: Group 2 : 2 noise exposures of 66 min; Group 2 (n=10) will be exposed to 85.5 dB(A) for 66 minutes, followed by an 18-minute rest period, then exposed to noise again for 66 minutes, for a total noise exposure time equivalent to 85 dB(A) for 2.5 hours.	Other: 2 noise exposures of 66 minutes; Exposure to 85.5 dB(A) noise for 66 minutes, followed by an 18-minute rest period, then exposure to noise again for 66 minutes
Experimental: Group 3 : 10 noise exposure cycles; Group 3 (n=10) will be exposed to 10 cycles of (13 minutes of noise at 85.6 dB(A) / 2 minutes of rest), for a total duration of noise exposure equivalent to 85 dB(A) for 2h30.	Other: 10 noise exposure cycles; Exposure to 10 cycles of (13 minutes of noise at 85.6 dB(A) / 2 minutes of rest)
Other: Group 4 : no noise exposure; Group 4 (n=10) will not be exposed to noise and will serve as a control.	Other: No noise exposure; No exposure to noise: subjects spend 2H30 in a soundproof cabin.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pure-tone audiometry thresholds	Variations in perceptive auditory performance related to the hearing threshold and the hearing threshold at each frequency will be compared between the experimental groups exposed to noise (1, 2 and 3) and a control group not exposed to noise (4). The exam will allow to determine the participants hearing levels at different frequences line according to Hughson-Westlake's procedure: 125, 250, 500, 1000, 2000, 3000, 4000, 5000, 6000, 8000, 10000, 12500Hz	End of follow-up period (up to 1 month)
Signal-to-noise ratio (SNR) at speech intelligibility threshold in noise	Variations in perceptive auditory performance related to the signal-to-noise ratio of the speech intelligibility threshold in speech audiometry in noise will be compared between the experimental groups exposed to noise (1, 2 and 3) and a control group not exposed to noise (4). The Speech-in-Noise (SIN) test assesses speech intelligibility in noise. It is conducted in a soundproof booth using headphones, with background noise set at 73 dB. After a brief training session, the participant repeats sentences presented at different levels of difficulty (signal-to-noise ratios ranging from +24 to 0 dB). Only key words are taken into account. The result corresponds to the noise level at which 50% of the words are correctly repeated.	End of follow-up period (up to 1 month)
Acoustic distortion products amplitude measured at acoustic reflex threshold	Variations in perceptive auditory performance related to acoustic distortion products amplitude measured at acoustic reflex threshold will be compared between the experimental groups exposed to noise (1, 2 and 3) and a control group not exposed to noise (4). PDA measurement combined with acoustic stimulation can therefore be used to assess the activity of various acoustic reflexes.The ECHOSCAN device automatically determines the reflex threshold by presenting contralateral acoustic stimuli of increasing intensity, each lasting 2 seconds. The stimulus intensity is limited to 100 dB HL.	End of follow-up period (up to 1 month)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stroop test to assess cognitive load	The Stroop test will be used. In the first part of this test, a participant will hear 2 types of pure tones:187 Hz tone or 448 Hz tone, each lasting for 690ms. The choice of a tone perceived ("low"or "high")should be made rapidly by clicking an appropriate category on an electronic support. . 24 stimuli will be randomly presented at a ratio 1:1. In the second part, the participant will be exposed to the words "Grave" (Low) or "Aigüe" (High) synthetically generated with a low voice (187Hz) or a high voice (448Hz). 4 combinations are possible: "Grave" with a low voice, "Grave" with a high voice, "Aigüe" with a low voice and "Aigüe" with a high voice. 48 stimuli will be presented at a ration 1:1:1:1 and reaction time will be measured. The Stroop test evaluates modifications in cognitive charge in the groups exposed to noise (1, 2, 3) compared to the control group (4) through the error rate.	End of follow-up period (up to 1 month) for all subjects included in the study
Baseline tone audiometry	This exam will be allow to determine the participants hearing levels at different frequences line according to Hughson-Westlake's procedure: 125, 250, 500, 1000, 2000, 3000, 4000, 5000, 6000, 8000, 10000, 12500Hz. It aims to evaluate the perceptive hearing performance of participants in group 1 (exposed to uninterrupted noise) compared to groups 2 and 3.	Up to 1 month, for subjects included in experimental groups (1, 2 and 3)
Assessment of speech perception in noise	This measure will be done with Speech-in-Noise (SIN) test. The test is conducted in a soundproof booth using TDH-39 headphones, in diotic binaural listening mode. The noise level is set at 73 dB Sound Pressure Level (SPL). To familiarize participants with the task while minimizing learning effects, the session begins with a single practice block of 10 sentences. The sentences are then presented in lists of 10. For each sentence repetition, only key words are scored. Each list tests 9 signal-to-noise ratios (SNRs) ranging from +24 dB to 0 dB in 3 dB steps. The total administration time for the three lists is under 4 minutes. The signal-to-noise ratio at which 50% of the words are correctly repeated is determined.	Up to 1 month, for all subjects included in the study
Assessment of Acoustic Distortion Products (ADP)	The EchoScan test will be used. Participants will receive auditory stimuli to measure the acoustic distortion product (ADP) generated by inner ear. ADP can be diminished by the middle ear reflex when sounds are delivered at high intensity. Thus, the stimulation intensity is limited to 100dB HL. This test allows to evaluate cochlear and middle ear functions and determine the acoustic reflex threshold activation which can be affected by auditory fatigue.	Up to 1 month, for all subjects included in the study

Collaborators and Investigators

• Sponsor: University Hospital, Montpellier
• Collaborators: National Research Agency, France
• Investigators: Study Director: Renan TARGHETTA, University Hospital, Montpellier

Study record dates

Study Major Dates

• Study Start (Estimated): May 15, 2026
• Primary Completion (Estimated): May 15, 2027
• Study Completion (Estimated): February 15, 2028

Study Registration Dates

• First Submitted: May 5, 2026
• First Submitted That Met QC Criteria: May 15, 2026
• First Posted (Actual): May 22, 2026

Study Record Updates

• Last Update Posted (Actual): May 22, 2026
• Last Update Submitted That Met QC Criteria: May 15, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Audiometry; pure-tone audiometry; Speech audiometry; audiometric threshold; speech intelligibility threshold; acoustic reflex threshold
• Other Study ID Numbers: RECHMPL22_0104; 2024-A01702-45 (Other Identifier: ANSM)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No