Between these evening sessions looking for her, I went out to the bridge for the first time in years. The 'acoustic anomaly' is still there -- and nowhere else. I can't find any mention of it online, haven't heard anyone talk about it. Not that I would.
Standing there at a little after one, I couldn't see any pedestrians in either direction. Nor did I pass any, coming or going.
I heard around a dozen cars this time and saw most of them by their headlights, about two seconds before. I heard a few stereos, but couldn't make out any songs.