( (let ((fm-freq ( "Fm Frequency" 2 400 1200 :log #t))) (* ( "Amplitude" 0 0.6 1) (oscil :frequency 0 (+ (hz->radians ( "Carrier Frequency" 1 200 1200 :log #t :glide #f)) (* (hz->radians fm-freq) ( "Index" 1 4 30 :scale 1 :glide #f) (oscil* fm-freq)))))))