The freehub is the actual component responsible for the noise. It consists of pawls and/or ratchet rings that engage and disengage, which leads to the sound.
In most cases, you will need to change at least the wheel hub to get a freehub system with different sound qualities (frequency and amplitude).
Chris King, DT Swiss, Industry Nine and other brands all offer systems with different engagement and noise associated with them.
I’m short on time to go into deeper detail. I will return or others can fill in the blanks.