The phrase referring hearing loud noise(s), meaning more than one noise. Used when hearing something rambunctiously annoying and irradiating. Only used when the sound is obviously heard; everyone hears.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.