See also the Norsonic Impact Ball:
(search for it; no links for me 
)
and the Rion Heavy Impact (Bang) Machine:
(search for it; no links for me )
This is because there’s no good definition for impact noise (i.e. walking sounds) through floors, nor is there a definition for the annoyance it causes. IIC (Impact Isolation Class, measured with the tapping machine) is a subtractive measurement, so it needs a calibrated source. Cindy Crawford’s downstairs neighbors famously sued her for the noise in her condo (with marble floors) and while the floors passed the standardized test (with tapping machine), if you walked around with high heels (as she was wont to do) the noise was measurably louder.
