NOISE INDUCED HEARING LOSS DR. J. OPOKU-BUABENG CONSULTANT OTORHINOLARYNGOLOGIST KATH /KNUST.

Outline Anatomy / Physiology of Human Ear Causes of Hearing loss NIHL Pathology Degree of Hearing loss Signs of Hearing loss Audiological findings Preventive measures Rehalitation

Anatomy / Physiology

Causes of Hearing Loss 1. Congenital 4.4% 2. Infection / Injury 17.1% 3. Age (Presbyacusis) 28.0% 4. Prolonged loud noise (Industrial deafness) 33.7% Others 16.8% Source: League for Hard of Hearing Hearing impairment Disability Handicap Psychosocial effects / impacts

Noise Induced Hearing Loss Noise-induced hearing loss (NIHL) is hearing impairment resulting from exposure to high decibel (loud) sound. Dependent on the following features of the sound: 1. Intensity 2. Duration 3. Type of Noise exposure

Types of NIHL Acute acoustic trauma Gradual developing NIHL NIHL caused by acute acoustic trauma refers to permanent cochlear damage from a one-time exposure to excessive sound pressure. This form of NIHL commonly results from exposure to high-intensity sounds such as explosions, gunfire, a large drum hit loudly, and firecrackers. Gradually developing NIHL can be caused by multiple exposures to excessive noise in the workplace or any source of repetitive, frequent exposures to sounds of excessive volume, such as home and vehicle stereos, concerts, nightclubs, and personal media players.

Intensity / Source of Noise Currently, the World Health Organization estimates that nearly 360 millions people suffer from moderate to profound hearing loss from all causes. According to a 2015 review, “Hearing loss due to recreational exposure to loud sounds” by the WHO World Health Organization (WHO), an estimated 1.1 billion young people may be at risk for hearing loss caused by unsafe listening practices.

Pathology Adaptation Reversible injury TTS – Hours to days Irreversible injury PTS – can be because of repeated attacks of TTS or a single loud noise exposure. TTS – there is Metabolic cochlea pathology PTS – mainly cause a Structural cochlea pathology

Normal / Damaged Cochlea Hair Cells

NIHL / Exposure period

Grade of Hearing Impairment

Signs of Hearing loss

Audiological findings Both NIHL caused by acoustic trauma and gradually-developed- NIHL can often be characterized by a specific pattern presented in audiological findings. NIHL is generally observed to affect a person's hearing sensitivity in the higher frequencies, especially at 4000 Hz. "Noise-induced impairments are usually associated with a notch-shaped high- frequency sensorineural loss that is worst at 4000 Hz, although the notch often occurs at 3000 or 6000 Hz, as well".

Prevention Public education / awareness Enforcement of social interventions by EPA, Law Enforcement Agencies, etc. Labour regulations with the use of protective devices. Hearing Conservation Programme

Public education The best, first option for protecting hearing is lowering the volume of sound at its source. Secondly, limiting the time of exposure to loud noise can reduce injury. Finally, physical protection from the noise can reduce its impact.

Workers in general industry who are exposed to noise levels above 85 dBA are required by the Occupational Safety and Health Administration (OSHA) to be in a hearing conservation program (HCP), which includes noise measurement, noise control, periodic audiometric testing, hearing protection, worker education, and record keeping.

Protective devices Ear plugs Ear muffs

Aural Rehabilitation BTE Hearing aid

ITC Hearing aid

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