Check Microphone With Line Diag Mode

Turn the ignition switch to ACC.
Press the button (b) twice with the button (a) pressed.

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NOTE: Pressing the button (a) for 3 seconds or more, or turning the ignition switch from the OFF to ACC position can exit the diagnostic mode.
{Line Diag} screen is displayed.
Check the microphone level with the {Microphone} in the {Line Diag} screen.

Courtesy of SUBARU OF AMERICA, INC.

Check that the microphone input level varies depending on the sound and voice.