Everyday exposure to noise
over time has an impact upon our ability to hear and on the degree of hearing
loss that develops. Continuous exposure to sounds above 85 db can cause
progressive hearing loss. Noise-induced hearing loss is the most common and
obvious outcome of noise pollution. It is also an important occupational health
concern due to high workplace noise levels. However, noise
pollution has also been associated with other health problems such as stress,
anxiety, high blood pressure, increases heart rate, heart disease. It may
manifest as disturbed sleep/ insomnia, headache, fatigue, irritability, loss of
concentration and decreased work efficiency.
Noise levels are also an
increasing concern in class rooms. The source of noise can be external such as
street traffic, playground noise, airplanes, etc. The source of noise can be
indoor, such as hallway noises, noise from other rooms etc. or noise within the
classroom itself such as conversation, noise from fans, lights, paper, etc.
Noise in a class room is not conducive to learning. Background noise in
classrooms interferes with auditory communication and adversely affects speech
perception and speech recognition. It interferes with language and reading
development and hampers academic performance. Attention and memory are also
adversely affected.
Speech intelligibility or
understanding is determined by the signal to noise ratio, which should be at
least 15dB i.e. the teacher should speak at least 15 db louder than the noise
in the classroom for the student to optimally comprehend what he/she is
hearing. For clear speech perception the background noise levels should not
exceed 35 dB in schools as recommended by the WHO. The reverberation time in
the classroom should be about 0.6 sec. Reverberation time is the length
of time required for sound to decay 60 db from its initial level in a
room. A longer reverberation time together with background noise increases noise
levels and makes speech perception even more difficult.
Hospitals are noisy and high
stress work environment places.
Because of high background
noise, such as in emergency dept. and OTs, the conversation has to be conducted
at higher dbs for clear speech communication (normal conversation is between
60-70 db).
Noise can interfere with oral
communication leading to mediation errors as a result of orders that are
misunderstood.
A noisy environment affects
performance of any complex task in a hospital as it reduces concentration. It
has been shown that “mental activities requiring a lot of working memory, such
as paying attention to a variety of different cues or performing a complex
analysis, are especially noise-sensitive”. Failure to hear a warning signal or
alarm over the general background noise in an ICU may have potentially
catastrophic outcome.
Noise affects effectiveness of
health care. Hence, hospitals too should have similar noise levels as
educational institutes.
Schools and hospitals are “silence
zones”. Silence zone is an area comprising not less than 100 m around
hospitals, educational institutions, courts, religious places or any other area
as per the Noise Pollution (Regulation and Control) Rules, 2000.
Every effort should be made to
reduce noise levels in hospitals for optimum delivery of health care.
Dr KK Aggarwal
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