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BASICS OF SOUND - Coggle Diagram
BASICS OF SOUND
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Sound Frequency
Comparative Sound Levels
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• MD-80 takeoff – 1,500 ft. alt. = 85 dB
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Sound frequency is measured in terms of cycles per second (cps), or hertz (Hz), which is the standard unit
for cps.
The normal human ear can detect sounds that range in frequency from about 20 Hz to about 15,000 Hz
All sounds in this wide range of frequencies, however, are not heard equally by the human ear most sensitive to frequencies in the 1,000 to 4,000 Hz range.
The decibel (dB) is a logarithmic unit used to measure sound level.The loudest sounds that can be detected comfortably by the human ear have intensities that are a trillion
times higher than those of sounds that can barely be detected.
Normal speech has a sound level of approximately 60 dB sound levels above 120 dB begin to be felt inside the human ear as discomfort. Sound levels between 130 to 140
dB are felt as pain (Berglund and Lindvall 1995)
The minimum change in the sound level of individual events that an average human ear can detect is about
3 dB.
Sound is a physical phenomenon consisting of minute vibrations that travel through a medium, such as air, and are sensed by the human ear 
Noise Metrics
As used in environmental noise analyses, a metric refers to the unit or quantity that quantitatively measures
the effect of noise on the environment.
Federal Aviation Regulations (FARs)
Federal Aviation Regulations (FARs) have been adopted in an effort to alleviate noise problems.
discusses noise standards for aircraft. It establishes the noise certification of aircraft and
categorizes them into stages based on noise level.
These factors are important when airport sponsors evaluate environmental impact. They are used to
conduct environmental assessments.