|  | Public Health Safety | Public Health

What Is a Noise Meter?

A noise meter, more commonly known as a sound level meter, is an instrument used to calculate the ambient sound pressure level in a given environment. Sound level meters have several practical applications, including the assurance of hearing safety standards in industry, consideration of acoustics in environmental design and for testing compliance with local noise laws.

  1. Function

    • A sound level meter consists of a microphone, which picks up sound in real time, sensing changes in air pressure level and converting the sound into electrical signals that are further analyzed by circuit components of the device. The sound level is calculated in decibels and is clearly displayed. Several types of sound level meters, intended for different purposes, such as measuring environmental sound, occupational noise and even vibrations, are available. Because these devices are intended for use in a variety of environments they are usually portable and battery powered.

    Common Uses

    • Sound level meters are used to test work environments, ensuring that noise regulations are observed. They are also used in urban planning to evaluate traffic noise, as well as noise from aircraft, trains and other transportation systems. Sound level meters may be used to evaluate the feasibility of noise-producing businesses within a neighborhood. Sound level meters are also used to investigate noise complaints from construction, music and traffic. They can be used to measure the level of crowd sounds at sporting events and concerts.

    Weighting Systems

    • There are different types of sound level meters, each designed to be responsive to certain frequencies. The most common weighting systems are the dBA and dBC networks. The dBA scale progressively falls off for frequencies below 500 Hertz. Low frequency sounds, such as thunder or the rumble of a bass drum, are not known to cause hearing loss and are treated as less important by this system. If the dBA scale is used to measure environments with a great deal of low frequency sound, high traffic areas or concerts for example, the reading may not accurately reflect the perception of noise within that space. On the other hand, the dBC scale gives roughly equal weight to low frequencies. Consequently readings made in the same environment may appear lower on the dBA scale than on the dBC scale, though the risk to human hearing remains the same.

    Considerations

    • Sound level meters are not able to distinguish between pleasant and unpleasant sounds. Repetitive construction sounds, from a jackhammer for example, may measure within the legal limit yet be considered noise by those in the vicinity. Sound level meters are able to differentiate between acceptable and damaging levels of sound, yet they say nothing of the qualitative experience of noise.

    Sound Analysers and VU Meters

    • Sound level meters are distinct from other sound measurement tools such as sound analyzers and volume unit meters. A sound analyzer measures the frequency content, or spectrum, of a signal. A VU meter measures the sound intensity level of audio equipment.

Public Health - Related Articles