We have experimentally studied shot noise of chaotic cavities defined by tw
o quantum point contacts in series. The cavity noise is determined as (1/4)
2e[1] in agreement with theory and can be well distinguished from other con
tributions to noise generated at the contacts. Subsequently, we have found
that cavity noise decreases if one of the contacts is further opened and re
aches neatly zero for a highly asymmetric cavity. Heating inside the cavity
due to electron-electron interaction can slightly enhance the noise of lar
ge cavities and is also discussed quantitatively.