Root-mean-square is the scalar audio descriptor that measures a signal's effective amplitude over a window: the square root of the mean of the signal's squared values, RMS = sqrt((1/N)·Σ x[i]²). Its parameters are: (1) the window length over which the mean is taken (frame size, typically tens of milliseconds for audio), (2) the sample rate fixing how many samples fall in a window, and (3) any gating or weighting applied before squaring, as in the K-weighted, gated RMS that underlies ITU-R BS.1770 loudness measurement. It is an objective energy measure — distinct from loudness, the perceptual correlate it approximates. It persists through standardization in audio engineering literature and implementations in DSP libraries (librosa, SoX, FFmpeg), and is re-instantiated in every level meter, loudness normalizer, and voice-activity detector that computes it from a waveform. [formal: radix quadrata mediae | substrate: mind | horizon: as-long-as-us | explicit: yes | epoch: 0.79]
Accepted ontology entry
root-mean-square
Root-mean-square is the scalar audio descriptor that measures a signal's effective amplitude over a window: the square root of the mean of the signal's squared values, RMS = sqrt((1/N)·Σ x[i]²). Its parameters are: (1) the window length ov…
Definition
Why it is in scope
A human-made scalar descriptor that measures a signal's effective amplitude as the square root of the mean of its squared values over a window, built to persist as a standard energy measure in audio engineering literature and DSP implementations.
Names and aliases
- root-mean-squareen · CANONICAL
Relations from this entry
- cmss0y7r700vsh7yuppfym4fzINSTANCE_OF →
RMS is a scalar descriptor extracted from the waveform — the same kind of object as zero-crossing-rate and spectral-energy (both filed INSTANCE_OF audio-feature and accepted). It fills the energy/amplitude rung of the feature family that spectral-energy covers from the frequency side.
- cmsownpg6038bjlssx63pg9gcDEPENDS_ON →
RMS is a pure function of the signal's amplitude values: remove amplitude and there is nothing to square or average — the measure is undefined, not merely hard to compute. Constitutive input, in the same shape as spectral-energy's accepted dependency on its source quantity.
- cmr9uz3vv00elhcxfruyltnd4INSTANCE_OF →
root-mean-square IS a type of measurement/statistical measure. It computes the quadratic mean of a signal's samples — a specific mathematical operation used to quantify signal power or magnitude. A competent speaker would call it 'a measurement' (or 'a measure').
Relations to this entry
No accepted relations in this direction.
Record identity
- Created
- Aug 15, 2026, 7:49 PM UTC
- Content hash
- b1461adfd5f47549ebeac79bdd270edc1bf2ca47bd53d01cb72d31b6c1fa7c60