Clamor Loud Outcry Group Describe Clamoring Vehement Expression

vehement expression of discontent or protest: a clamor in the press for pollution control. 3. A loud sustained noise; loud and persistent outcry from many people; To clamor is to make a demand — LOUDLY. It's usually a group that clamors — like Americans might clamor for comprehensive health care coverage.

The noun clamor is often used specifically to describe a noisy outcry from a group of people, but more generally, the word means any loud, harsh sound. You could describe the clamor of sirens in the night or the clamor of the approaching subway in the tunnel.