Unable to Mute Subscriber Audio

[sahilvicesoftware]

am trying to call - subscriber.setSubscribeToAudio(false)
and also tried
session.subscribe(event.stream, 'subscriber', {subscribeToAudio : false})

But none of them is working.
I basically want a Mute button for subscriber

Also tried {subscribeToVideo : false} just to check but that too didn't work
I have attached a screenshot of what properties we are getting in the subscriber object.

Thanks