Absorbent in cavity

[xmor]

Hi there to everyone!

I was wondering if a cavity between two studs is not perfectly "filled up" with sound absorbing material (e.g rockwool) but a portion of it...say 80%. Will this affect significantly the STC of the sound insulating drywall partition? Bare in mind that I'm talking about the witdth of the cavity and not the depth...What's the optimum density of the abrobent for cavities with depth 50 - 100mm?

Thanks all for your help