Signal-to-Noise Ratio

A measure of the strength of a desired signal relative to background noise, expressed in decibels (dB). In accessibility, signal-to-noise ratio is critical for the effectiveness of auditory interfaces: if background noise is too high relative to device audio output, speech instructions, sonification cues, and other auditory feedback become unintelligible. Maintaining an adequate signal-to-noise ratio is essential for assistive technologies that use audio — including screen readers, navigation aids, and hearing assistive devices — to function reliably in real-world environments where ambient noise levels vary widely.