INTRODUCTION:
Hearing impairment is the most common sensory disability found among
human beings. (1) After aging, noise exposure either
occupational or recreational is the leading cause. Noise induced hearing
loss (NIHL) once established, is irreversible, only partly manageable
though totally preventable. (2) WHO estimated that 1.1
billion young people (12-35 years) are at risk of hearing loss due to
recreational noise exposure. (3)
Leisure time noise exposure has become a great concern of public health.
Occupational noise hazards have been evidently defined and protective
measures are adopted globally. But no such preventive methods are
clearly devised for the protection of dreadful effects of recreational
noise. (4) Noise induced acoustic trauma has been
conventionally described to effect high tone frequencies when assessed
by Pure Tone Audiometry (PTA). This high tone frequency loss is
graphical representation of response of hair cells in cochlear base.
Based on the guidelines of Health and Safety Executive it was proposed
that the frequency where notch appears in a pure tone audiogram suggests
the specific type of noise to which one was exposed. Intense low
frequency noise can cause maximal loss at lower frequencies while
intense high frequency sound can predominantly affect higher
frequencies. (5)
Hearing difficulty not only hinders the functional capacity of an
individual but also affects the intellectual health of a potential mind.
A large population-based study discovered that low frequency hearing
loss (0.25-0.5kHz) among young and middle age people(6) while generalized hearing loss among elderly
population considerably affect mental health and quality of life.(7)