Audio Fundamentals
White noise is a random audio signal that contains equal energy across all frequencies within the audible range. It produces a bright, hissing sound and is commonly used for equipment testing, acoustic analysis, and sound synthesis.
In white noise, every frequency has the same amplitude, resulting in a constant energy level per hertz. This gives it a flat frequency spectrum when viewed on a linear scale. Because high frequencies occupy more bandwidth than low ones, white noise sounds bright or sharp to the human ear, which perceives sound on a logarithmic rather than linear frequency scale.
White noise is widely used in professional audio and acoustics. Engineers use it to test the performance of amplifiers, loudspeakers, and signal paths, as its uniform spectrum reveals how equipment or environments alter the frequency balance. It is also used to generate impulse responses for system calibration and to mask unwanted sounds in studio or office environments.
In synthesis, white noise serves as a source for percussive or atmospheric sounds. Filters can shape its spectrum to create other forms of noise, such as pink or brown noise, each with distinct tonal qualities. White noise is also employed in modulation and randomisation processes to add texture or realism to electronic sounds.
Although pure white noise is theoretically infinite in bandwidth, in practice it is limited to the frequency range of the system producing it, usually 20 Hz to 20 kHz. Its predictable and uniform properties make it an essential reference signal in both testing and creative sound design.
