Help Topics - O

Occupational deafness

The reduction in hearing acuity caused by excessive exposure to high noise levels at work. This is in addition to recreational noise exposure caused by factors outside of the workplace which may be additive.

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Occupational exposure limits

8 hour time weighted average levels for each material under consideration. Limits are published by such bodies as OSHA, HSE etc. in each country.

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Occupational exposure standards

These are standards applied to all materials and, in general, exposures below the standard would be regarded as demonstrating adequate compliance with the relevant statutory requirements.

Occupational hygiene

The science associated with the anticipation and recognition of workplace hazards and the evaluation and control of subsequent risks to health.

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Octave

An interval between two sounds having a ratio of two to one in terms of their frequency span. There are 8 octaves on a piano and the audio range can be covered by 10 octaves in the range 20 Hz to 20 kHz.

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Octave band

A single band of frequencies where the upper limit is twice the lower limit. Octave bands are classified according to their geometric center frequency based on the internationally standardized 1000 starting point. The 1000 Hz or 1 kHz band has limits of about 707 and 1414 Hz.

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Octave band analysis

The analysis of a complex or simple sound into its constituent parts based on the interval of octave bands across the audio range. A full octave band analysis will contain 9 or 10 readings from 32 Hz to 8 kHz or 16 kHz.

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Octave band level

The sound pressure level usually integrated over a time interval containing only the sounds with frequency components within the pass band of each octave band filter.

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Organic

This means a substance that is carbon based.

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Oscillation

A simple vibration that varies with time alternatively increasing and decreasing sound pressure at a receiver position due to the movement of an object.

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OSHA

The Occupational Safety and Health Administration in the United States. A division of the Department of Labor charged with dealing with the health and welfare of the working population  that issues guidelines and legislation to control the hazards at work.

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Outer ear

The only visible part of the human hearing mechanism consisting of the pinna, or ear lobe. The purpose of the pinna is to direct the sound down the ear canal to the eardrum and the interface to the middle ear when the sound waves are converted to mechanical vibrations of the tympanic membrane.

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Overall noise level

The total broadband noise level containing all the frequencies that are present in the sound. This is usually expressed as the A weighted noise level in dB, but can also be a C weighted level for specific measurement purposes.

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