vad

Vad, commonly written as VAD when referring to the acronym, has several uses. In digital signal processing, VAD stands for Voice Activity Detection, a class of algorithms that determine whether a segment of audio contains human speech. Real-time VAD is used to preserve bandwidth in telecommunication by turning off transmission during silence, and to improve the performance of noise reduction and speech recognition systems. Methods range from simple energy-based detectors that compare short-term signal energy to a threshold, to more sophisticated spectral or statistical approaches using zero-crossing rate, spectral entropy, Gaussian mixtures, or neural networks. VAD systems must contend with noisy environments, music, and rapidly changing noise; performance is typically reported via false-alarm and miss rates, or DET curves. In practice, VAD is integrated into VoIP, video conferencing, mobile telephony, hearing aids, and automatic speech recognition pipelines, often as a precursor to encoding, compression, or enhancement stages.

In business, VAD also stands for value-added distributor, a channel partner that adds services or capabilities to a product before reselling it to distributors or end users. A VAD may provide integration, configuration, packaging, training, technical support, and marketing resources, acting as a bridge between manufacturers and resellers. They often operate in IT, cybersecurity, electronics, and software ecosystems, helping vendors reach markets with additional services that differentiate products.