The subpatcher "audio" contains the inputs (adc) and outputs (dac) for the audio signals in Pd. By clicking the buttons across the top, you send a test-tone to the accompanying output. The displays marked "Tone Amplitudes" verify the signals being sent. The displays show the output strength in dB: 80dB for normal, 60dB for soft.

The input amplitudes (also in dB) are displayed to the right of the tone amplitudes. By clicking the "Through" toggle you are passing any input signal directly to the first two channel outputs.

The audiostatus message in the lower right requests Pd to display any known adc or dac errors. Note: The kinds of errors captured and the time since the last error are displayed in the shell from which you launched Pd.

MIDI

The displays beneath "MIDI IN" will reflect any pitch and dynamic MIDI values seen. The controller is the "sustain pedal" controller, especially useful for testing Disklaviers.

The subpatcher "midi" generates repeating middle-C to the midi output.