Just an observation, but to my believe lightweight aluminium bikes make more noise on hot days than cooler days. For that matter, a lot more noise than any other steel bike, on any given day. I ride amongst bikes a black GIANT TCR ZERO, which on a really hot day "pings" when I stand out of the saddle. I've had it serviced and tuned, the whole works (wheels included) yet the little "ping" remains.
On the other hand, my trusty steel horse an OLMO, is quiet as can be.
Does steel frames absorb more "background" noise than a thin walled lightweight aluminium frames?