The Keysight (formerly Agilent) Technologies 8903B audio analyzer provides unparalleled versatility and performance for audio measurements from 20 Hz to 100 kHz. The 8903B combines the functionality of a low-distortion audio source, high-performance distortion analyzer, frequency counter, ac voltmeter, dc voltmeter, and SINAD meter into one compact package. With microprocessor control of source and analyzer, the 8903B can perform stimulus-response measurements (such as signal-to-noise ratio and swept distortion) automatically with no additional equipment. For ease of use, most measurements on the 8903B are made with only one or two keystrokes. The 8903B automatically tunes and autoranges for maximum accuracy and resolution. For quick identification of input signals, the analyzer counts and displays the input frequency in all ac measurement modes.