Audio test systems are used for testing speakers, amplifiers, cell phones, and other analog/digital audio equipment. NI audio test systems have been deployed in many facilities for research and development as well as automated production line test. NI analysis software for audio includes total harmonic distortion (THD), frequency response (FRF), swept sine, and signal-to-noise ratio (SNR). NI also offers mixed signal measurement in conjunction with audio for RF, video, and DC power.