Background Noise

The sum of unwanted or competing sound in an environment — traffic, construction, conversation, HVAC systems, weather — that is present alongside a signal of interest. Background noise is characterized by sound level (dB), spectral content, duration, and steadiness versus impulsivity, and is strongly linked to health outcomes, cognitive performance, and communication access. For accessibility, background noise is a first-order concern: it degrades speech intelligibility for Deaf and Hard-of-Hearing users of hearing aids and cochlear implants, masks acoustic vehicle alerting systems for blind pedestrians, disrupts screen-reader speech output, and interferes with voice-interface use. WHO environmental noise guidelines set population-level limits; accessibility practice extends this to signal design, hearing-technology interoperability, and multimodal redundancy.