Does Sound Conditioning Protect Against Temporary Hearing Damage

Does Sound Conditioning Protect Against Temporary Hearing Damage

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).

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