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• Acoustics is the science of sound, including the generation, transmission, and effects of sound waves.
• Sound is defined as a rapidly varying pressure wave within a fluid medium such as air or water that is capable of being detected by the human ear.
• The decibel (dB) is a measure of the intensity of sound. The decibel scale runs from the faintest sound the human ear can detect, which is labeled 0 dB, to over 180 dB, the noise of a rocket at the pad during launch
• A bel is another unit for comparing intensities of sound: 1 bel equals 10 decibels.
• Loudness is the human perception of the strength of a sound.
• Speed of sound c = 49 √(460+𝑇)
• SI (metric) units, the formula for the speed of sound (c) c = 20 √(273+𝑇)
• By definition, noise is any disagreeable or undesirable sound that interferes with rest, sleep, mental concentration, or speech communication.
• Ambient noise is the all-inclusive noise associated with a given environment at a specified time.
• Sound control is an important consideration in the design of a project.
• The sound transmission class (STC) is a single-number rating system that rates the ability of a wall or other construction to block sound transmission.
• Sound transmission loss (TL) is a measure of sound insulation provided by a structural configuration.
• The noise isolation class (NIC) is a single number rating used to measure noise reduction between two areas or rooms.
• An impact sound is produced by the collision of two solid objects. Typical sources in a building are footsteps and objects dropped or thrown onto an interior surface (e.g., wall, floor, or ceiling).
• The impact insulation class (IIC) is a number rating, based on standardized test performance, for evaluating the effectiveness of assemblies in isolating impact sound transmission.
• The impact noise rating (INR) is an obsolete rating system that rates the ability of floor ceiling assemblies to resist the transmission of impact sound.
• Sound absorption is a property of materials that causes a reduction in the amount of sound reflected from a surface.
• the absorption coefficient (a) is a measure of the sound-absorbing ability of a surface.
• The noise reduction coefficient (NRC) is also used to measure the ability of a material to absorb sound rather than reflect it.
• The ceiling attenuation class (CAC), previously referred to as the ceiling sound transmission class (CSTC), rates a ceiling’s efficiency as a barrier to airborne sound transmission between adjacent closed offices.
• The room criteria (RC) are a single-number noise rating system used to diagnose and rate the HVAC noise exposure in a room.
• The noise criteria (NC) is a single-number noise rating system used to rate continuous noise in a room from all types of HVAC equipment (e.g., fans, mixing boxes, diffusers). HVAC air terminal products (e.g., diffusers, grilles, and so forth) are commonly specified and reported in NC, rather than RC