How do you go about to assign keys for symbols that are not letters? One way is to put them on keys that have labels slightly resembling the symbol, and some of the symbols in Sonova actually are placed like that. But, this can only be seen on a US-keyboard; all other countries have key labels in wildly different locations.
Another way is to have them arranged according to some logic of the symbols themselves. Typing Spectromorphology you can find pitched (circle) on the upper row of letters, dystonic (diamond) on the row below, and complex (squares) on the bottom row. Pressing shift gives an open variant or another related feature of the symbol. Option/alt pressed to type gait or granularity mimics the layout of the figures in the book and so on.
A lot of experimenting and use in practice has gone in to this organization. But, if needed you can make your own layout to fit your personal needs, free tools are available for download for Macintosh and Windows. As long as the Keyboard Layout’s name starts with “Sonova”, it will also turn up in the Aural Sonology plug-in settings in the Acousmographe.