Does Sound Conditioning Protect Against Temporary Hearing Damage

Imperial College Healthcare NHS Trust32 enrolled

Overview

This research project will contribute to the research surrounding the effect on the ear after noise exposure. This ever-growing field of research has never been more applicable than now with the increase of recreational noise exposure. Noise is the leading cause of preventable hearing loss and excessive occupational noise along with recreational noise exposure can cause a devastating disability. The World Health Organisation (WHO) estimates 1.1 billion young people could be at risk of hearing loss due to unsafe listening practices. One of the mechanisms that could increase the resistance against noise induced hearing loss is 'sound conditioning'. Animal studies have found that prior exposure to low level noise over a period of a few weeks can 'condition' the ear. This conditioning then reduces the susceptibility to high level exposure i.e. strengthening the ear. In this study, the investigators aim to determine whether previous exposure to loud noise can condition the human ear, reducing the temporary hearing loss and temporary tinnitus ("ringing in the ear") that sometimes occurs after attending a loud nightclub or live music event. There are many implications of this research. The long-term effects of non-damaging lifetime noise exposures are unclear. Principally, this research will allow better understanding about noise susceptibility and resistance, allowing for appropriate interventions, thus improving care. For instance, an individual more susceptible due to low prior exposure can be advised of risks and encouraged to use hearing protection. This thesis will increase the knowledge base surrounding the impacts of noise on hearing and educate others in understanding these.

Objective: This study explored if sound conditioning (recent noise exposure) protects individuals against temporary hearing damage. Design: Participants attended two sessions in this between-group repeated measures trial; the first included a noise exposure structured interview. Five dependent variables were measured before and after attending a loud event: EFA, DPOAE, MEMR, QuickSIN and Tinnitus. It was hypothesised those with high recent noise exposure, Group 1 (noise unit \> 0.323), would experience less temporary hearing damage than irregular attendees, Group 0. Sample: Thirty-two normal hearing participants with a mean age of 26 ± 3.3 years (16 males, 16 females).

Study Type

OBSERVATIONAL

Enrollment

Interventions

Session One Test BatteryDIAGNOSTIC_TEST

Prior to noise exposure: Test battery - High-frequency audiometry, Distortion Product Otoacoustic Emissions, Middle Ear Muscle Reflex, Speech-in-Noise test (Around 35 minutes with breaks if required) * Extended Frequency Audiometry (\~ 8 min), 0.25-16 kHz: Participants will be asked to press the button when they hear a sound through the headphones in a soundproof booth. * DPOAE (\~ 5 min), 0.5-10 kHz: A small tip will be placed in participants' ear and they will hear a sound. The tip measures a response from hair cells in the cochlea and they will not need to do anything. * MEMR (\~ 8 min), 4 kHz: A small tip placed in both ears and again a sound heard, however, this sound will gradually get louder until an involuntary muscle reflex is noted. * Speech-in-Noise Test (\~ 5 min): Participants asked to repeat back a list of words as best as they can. * Tinnitus: Participants were also asked if they experience any tinnitus i.e. bilateral, lasting \> 5 minutes. This was reported as Y/N.

Session Two Test BatteryDIAGNOSTIC_TEST

Exposure at single loud music event (Important that this is part of participants' normal recreational routine, and specifically require that attendance is not prompted by participation in this study): Participants to use sound level meter provided from the Audiology Department at Charing Cross Hospital or sound level meter applications to measure sound levels inside the loud event. Morning after exposure: Repeat test battery from session one - Ideally as soon as event is over.

Session Three Test BatteryDIAGNOSTIC_TEST

1 week later (recovery): Repeat test battery.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 35 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * 18-35 years old (as age can affect cochlea hair cell function) * Healthy participants with no significant medical conditions * 0.25 Hz to 8 kHz PTA \<= 20 dB HL indicating normal hearing * Otoscopy to ensure no otological abnormalities * No exposure to abnormally loud sounds in the past 24 hours * Full capacity to consent * Able to speak fluent English so information sheets, consent forms and instructions are fully understood * Previous intention to attend a loud noise event during the course of the study, without the use of hearing protection Exclusion Criteria: * No permanent tinnitus or hyperacusis (sensitivity to loud sounds) which would mean participants are unable to undertake all testing and a high exposure event * Any contraindications for testing i.e. excessive wax, infections * One or more frequencies 0.25 Hz to 8 kHz \> 20 dB HL in either ear * Not involved in current research or have recently been involved in any research prior to recruitment

Outcomes

Primary Outcomes

PTA (EF)

Extended Frequency (EF) PTA with results measured in dBHL where higher values mean worse hearing thresholds. Hearing thresholds were measured in the two sessions (unfortunately session three was not completed). A single dB HL value was calculated by averaging results across participants in each session (Extended frequency audiometry (EFA) comprised of averaging 2-16 kHz).