Flange squeal (AKA 'squange fleal' by ridgewayjr) is a screeching train/track friction sound, commonly occurring on sharp curves, presumably caused by the lateral sticking and slipping of the wheels across the top of the track (wikipedia). This is important because it will help you pin down the GZ of this geocache!
We have a similar cache just down the street to the west (GC83XN7). Buses 189, 89, 41, and 40 go right past here, or it's a 10-15min walk north from Keele Station.