The purpose of this chapter is to provide an understanding of noise in the environment that is sound energy that is objectionable because of its physiological and psychological effects on humans. This includes a review of the properties of sound including understanding of how sound is generated and propagated; identifying the properties of sound including wavelength, frequency, amplitude and speed; awareness of the differences among sound power, sound intensity, and sound pressure and how each is calculated and expressed; familiarity of the inverse square law and how it relates to sound reception; understanding of how sound is measured and limitations of sound-measuring instruments; familiarity of weighting networks, their use, and limitations; familiarity with the calculation average sound pressure levels; familiarity of sound exposure descriptors such as A-weighted sound exposure level, equivalent sound level, and day–night sound level; understanding of how loudness relates to sound pressure levels; understanding of how sound is transmitted from the external ear to the brain; familiarity of effects of environmental noise; familiarity of occupational noise exposure concerns and characteristics of noise-induced hearing losses; understanding of the nature of community noise problems; knowing what regulatory efforts have been applied to noise exposures in work and community environments; and understanding of what noise control options are available for community environments.