8.1 Noise Flashcards
What determines the pitch of the sound?
wavelength
What is measured in hertz (Hz), or waves per second.
Frequency
What determines the loudness of a sound?
amplitude (height of sound waves)
What type of dB ‘weighting’ is being described below:
Filters out the low frequencies and slightly emphasizes the upper middle frequencies around 2-3 kHz, essentially mimicking the human ear.
A weighting
What type of dB ‘weighting’ is being described below:
Almost unweighted, with only slight filtering at high and low frequencies. Intended to be used when measuring high sound pressure levels such as aircraft noise.
C weighting
With the exception of really loud noises (130dB+) it is the accumulated noise dose that causes hearing loss.
True or False?
True
To determine the average dose received over a given time an integrated sound level meter balances out the peaks and troughs to calculate a single figure that would give the equivalent dose over that time. This equivalent level is known as…
Leq
If the Leq is calculated for an 8 hour working day it is known as…
LEPd (Daily personal noise exposure).
Noise exposure levels equivalent to 80dB(A)LEPd (the lower exposure action value), can be calculated using the ‘rule of three’.
What is the rule of three?
80dB(A) over 8 hours is the same noise dose as 83dB(A) over 4 hours.
Double the noise level (increase by 3dB) over half the time gives the same dose.
Permanent hearing damage can be caused in two ways. Which one is being described below:
Sudden, extremely loud, explosive noises, e.g. from cartridge-operated machines can cause immediate permanent damage.
blast deafness or acoustic trauma
What is being described below:
ringing, whistling, buzzing or humming in the ears, may also be caused as
a result of exposure to workplace noise and may be an acute (short term) effect or have a chronic effect (long term).
Tinnitus
What is the probable noise level in dB being described below:
The noise is intrusive but normal conversation is possible
80dB
What is the probable noise level in dB being described below:
You have to shout to talk to someone 2 m away
85dB
What is the probable noise level in dB being described below:
You have to shout to talk to someone 1 m away
90dB
There are three noise action levels defined in the Control of Noise at Work Regulations. At each level the employer is required to take certain steps to reduce the
harmful effects of noise on hearing.
What is the Time Weighted Average (TWA) lower LEPd exposure action value in dB?
80 dB(A)
