White noise basics
White noise glossary
Quick definitions of the terms you will meet in guides about white noise and sleep.
Short answer
This glossary defines key terms: decibel (loudness), hertz (pitch), frequency, octave, masking, white, pink and brown noise, sound pressure level, tinnitus and more.
Sound terms
- Decibel (dB): a unit for loudness. It is logarithmic: every 10 dB is roughly twice as loud.
- dBA: decibels adjusted for how the human ear hears, giving less weight to very low and very high pitches. Most noise limits use dBA.
- Hertz (Hz): cycles per second, the unit for pitch. Higher Hz means higher pitch.
- Frequency: how fast a sound vibrates. The same as pitch.
- Octave: a doubling of frequency, for example 100 Hz to 200 Hz.
- Sound pressure level (SPL): the physical measure behind decibels.
- Spectrum: how a sound's power is spread across frequencies.
Noise terms
- White noise: equal power at all frequencies. See white noise.
- Pink noise: power falls 3 dB per octave. See pink noise.
- Brown noise: power falls 6 dB per octave. See brown noise.
- Masking: when one sound makes another harder to hear. See how it works.
- Sound masking: deliberate background sound used to reduce distraction or improve privacy.
- Noise cancelling: creating opposing sound waves to reduce noise. Different from white noise.
- Loop: a recording that repeats without a gap.
Sleep and baby terms
- Sleep regression: a temporary period of more night waking. See sleep regression.
- Colic: intense, unexplained crying in a healthy baby. See colic.
- Startle reflex: a newborn's automatic reaction to a sudden sound or movement.
- Safe sleep: guidance to reduce risks, including back sleeping on a firm flat surface with a clear sleep space.
- Sleep timer: a feature that stops the sound after a set time.
- Fade out: gradually lowering volume before the sound ends.
Hearing terms
- Tinnitus: hearing a sound, such as ringing, that has no outside source. See tinnitus.
- Hearing loss: reduced ability to hear, which loud sound over time can cause.
Frequently asked questions
What does dB mean?
Decibel, a unit of loudness on a logarithmic scale.
What is the difference between Hz and dB?
Hz is pitch. dB is loudness.
This page is general information, not medical advice. Talk to your pediatrician about your baby's sleep and hearing, and follow current safe sleep guidance.