motorshield R3 control whithout pwm

Other Hardware Motors, Mechanics, Power and CNC
1

Hallo,

I want to feed a 50 W 8 Ohm Loudspeaker whith a random noise signal with
Frequences between 10 to 500 Hz.
I use a Arduino and a Motorshield at Output A.
If I use PWM on Pin 3 it works, but there are some Interfereces whith- I suppose- the PWM Frequenc .
My question : can I use Digital Write in any way ?

Thanks for answers