Help Topics - H

Hand held measurements

Measurements made over a short period of time where the monitoring instrument is held in the users hands as opposed to being permanently mounted on a tripod or on a bench. usually measurements like this are done in 5 to 10 minutes at each position.

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Harmonic

A sinusoidal component whose frequency is a whole number multiple of the fundamental frequency of the wave. If a component has a frequency that is twice that of the fundamental it is referred to as the second harmonic.

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Hearing

The subjective response of human beings to acoustic energy or sound waves. The hearing capability of an individual must be protected against high noise levels to prevent it from deteriorating over time when working in noisy environments.

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Hearing conservation program

A planned program to document the noise exposure of employees with the purpose of ensuring that all are adequately protected form the harmful effects of high noise levels in the workplace. Possible outcomes of such a program could include the prescription of suitable hearing protectors, the attenuation of noisy machinery or the rotation of job functions between different workers during the day.

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Hearing level

A measured threshold of hearing at a specified frequency, expressed in decibels, relative to a specified standard of normal hearing. The deviation of an individual’s threshold from the zero reference level in the audiometer.

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Hearing loss

The general term for the impairment of hearing acuity. The amount of this hearing acuity, in decibels, measured as a set of hearing threshold levels at specified frequencies. Hearing loss can be caused by a number of factors such as loss in the conductive mechanisms in the ear, loss originating in the sensori-neural parts of the auditory nerves or by excessive exposure to high noise levels at work.

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Hearing protectors

Devices worn by an individual to protect against excessive exposure to high noise levels. These can be of the internal or external types. Internal types include ear plugs that are inserted into the ear canal while external types are mainly ear muffs that fit completely around the ear lobes.

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Hearing threshold level

The amount, in decibels, by which an individual’s threshold of audibility differs from that of a normal standard audiometric threshold.

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Heat exhaustion

A heat related illness characterized muscular weakness, distress, nausea, vomiting, dizziness, pale clammy skin and fainting.

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Heat stress

The physiological strain caused by an increase in core body temperature above safe levels where the individual is at risk of overheating.

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Hertz

The international unit of frequency of an oscillation, numerically the same as cycles per second. Abbreviated as Hz.

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HSE

Health and Safety Executive (UK Agency)

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HVAC

The general term for all acoustic measurements involving the subject of Heating, Ventilation and Air Conditioning.

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