The CTD-8 makes it possible for one person to setup or verify all the AES/EBU digital audio channels in his facility D easily, quickly, and accurately. The unit produces a hands-free audible and visual sequential voice ID for each channel, eliminating the need for external generators or extra personnel to switch between sources. In addition to the voice ID's, the CTD-8 includes AUX channel tones allowing both narrow and wide band frequency response testing, and for spectrum analyzers, a pink noise generator is included. Finally, there is a modified sine wave output that can be monitored at the audio system output to verify that there has not been an audio phase reversal in the system. Audio phasing or polarity can be verified either visually (oscilloscope or hand-held video scope) or with an approved polarity detector (CL-1 Channel Listener).