Audio Spectrum AM Menu Key Sequence: Measure or (Shift + 4) > Audio Spectrum > Audio Spectrum Audio Spectrum AM Menu Span Press to set the AM audio spectrum span. Use the numeric keypad, the rotary knob, or the arrow keys to set the value. Valid values are 2 kHz, 5 kHz, 10 kHz, and 20 kHz. Back Press to return to the Measurements menu.