Routes by terrain
Four kinds of ground: city lanes, park circuits, forest paths and waterside promenades. Each one changes what there is to notice.
City
4 routesHard ground, kerbs, doorways, crossings. City walking is the noisiest of the four and the one that rewards attention most, because almost everything in it is man-made and can be counted.
Park
4 routesMown grass, gravel and a perimeter you can usually see the whole of. Parks are the easiest place to learn the script, because the route repeats itself and you cannot get lost.
Forest
2 routesRoots, leaf litter, dappled light. Forest routes ask you to slow down for footing and then give you the most to hear, since the canopy takes the wind and hands it back in pieces.
Waterside
3 routesAn edge, a railing, a long level stretch. Water routes are the flattest here, and the only ones where the sound of the ground is replaced by the sound of something moving past it.