I backed up twenty feet, trying to pick out the trace of a song emerging from the falls and the pools. This is no easy task, demanding equal parts concentration and imagination. Years ago, while on a backpack through the Sierra Nevada range, I made it my job to learn how to optimize listening, and often camped beside promising waters to study the aesthetics of stream song. Pleasing tones seem to emerge best just after dusk, when the air cools down and vapor collects in the canyon bottoms to enhance the bass tones concealed by the dry heat of the day. I noticed that water falling over a rock may produce distinct intervals of notes, essentially rhythms, that either harmonize or cancel intervals created in nearby falls.
Water dropping short distances into deep pools produces the most musical tones.
Like taking in a distant view through tall trees, a song may alter inexorably as a person moves a few feet in either direction. A man I once met on a trail on the upper Kings River insisted that certain streams hold every song ever sung. After testing his statement for years, I conclude that he overstated the case. Large roaring streams may contain every song, but they achieve this dubious distinction by producing white noise that buries all the pure tones. It's like saying radio static holds every song.