Muting a grand

[Ron Nossaman]

>However, to block airborne vibrations, don't use foam.  Air passes right
>through it.  Use dense materials with lots of weight to them.  Heavy felt
>(REALLY heavy) is ideal.  Think in terms of that stuff they use under the
>carpets of cars.  Heavy carpet is perhaps a more cosmetic solution.
>
>To keep a solid surface (e.g. a wall) from vibrating in response to airborne
>sound, add mass to reduce its compliance.

Lead sheeting is widely used for this.

Ron N