Compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony and released in 1982.
The decibel (symbol: dB) is a unit of measurement used to express the ratio of one value of a physical property to another on a logarithmic scale.
The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.
A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit.
The metric system is an internationally adopted decimal system of measurement.
In mathematics, a ratio is a relationship between two numbers indicating how many times the first number contains the second.
In physics, sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.