Noise Measurements

Available Instruments

Portable and precision sound-level meters, sound monitors, noise-exposure integrators, audiometers, octave-band analyzers, graphic and wide-band recorders, loudness, computers, and others.

Power Required

Portable instruments are usually battery powered. Laboratory instruments or computing-type loudness meters are supplied from normal power lines with 117 volts, 60 cycle ac. Their power demand is less than 500 volt-amperes.

Range of Operations

Usually from 30 to 140 dB. Usually from 20 to 20,000 Hz.

Cost

Sound-level meters, from $500 up. Frequency analyzers, from $2000 up.

Partial List of Suppliers

Ametek, Inc., Mansfield and Green Div.; B & K Instruments, Inc.; Larsen David Laboratory; Quest Technologies; H.H. Scott.

Noise measurements are usually conducted for one of three purposes:

To understand the mechanisms of noise generation so that engineering methods can be applied to control the noise To rate the sound field at various locations on a scale related to the physiological or psychological effects of noise on human beings

To rate the sound power output of a source, usually for future engineering calculations, that can estimate the sound pressure it produces at a given location

This section describes a few frequently used terms and units proposed for the study of sound and noise; most are quite specialized. It also describes techniques and instruments to measure noise.

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