White Noise, Pink Noise, and Masking
By: Tony Hoover, FASA, INCE Bd. Cert., MCH Principal
Today is International Noise Awareness Day, a great day to inaugurate our new Tech Blog series, discussing acoustical and media system & infrastructure topics of interest.
We thought it would be appropriate to share quick descriptions and audio samples of White Noise, Pink Noise, and Masking. These can be used as sound sources to measure and even to improve architectural acoustics. We hope to provide some clarity about what they are and how they sound.
White Noise is rarely useful in architectural acoustics, despite being a widely used term. White Noise does not happen naturally, but can be artificially generated using signal processing. It is defined as having equal energy per frequency; the low-frequency bands have many fewer frequencies than the high-frequency bands, the plotted spectrum has a steep incline, and it sounds very “hissy”. Listen to White Noise below.
Pink Noise is routinely used as the sound source for common acoustical measurements, such as for sound isolation, reverberation, and audio systems. Pink Noise has equal energy in each band, resulting in the very useful “flat” spectrum. Most waterfalls generate sound that is essentially Pink Noise. Listen to Pink Noise below.
Although often inappropriately referred to as White Noise, Masking is almost the opposite. When properly tuned, it sounds very much like an HVAC system, and therefore blends into the background, and can greatly improve speech privacy and reduce disruption, everywhere from open-plan offices to bedrooms. Listen to Masking below.
White Noise, Pink Noise, and Masking each have specific meanings. They sound very different from each other, too.