Signal-to-Noise Ratio

Signal-to-Noise Ratio — A basic signal-quality measure expressing the ratio of desired signal power to noise power, commonly reported in decibels.

Definition

For a power ratio:

SNR_dB = 10 log10(P_signal / P_noise)

An amplitude ratio uses 20 log10 only under the appropriate equal-impedance assumptions.

Measurement Boundary

The method used to separate "signal" from "noise" must be explicit. Estimating a noise floor from silent speech regions may not represent non-stationary noise over the complete recording.

Higher Is Not Automatically Better

Higher SNR generally indicates a cleaner observation, but aggressive enhancement can also remove useful signal components. For ASR and biometric systems, subjective audio quality and model accuracy are different metrics.

Related Concepts

• Dynamic Range
• Speech Enhancement
• FFT
• Speech Separation Project