We define the space of sound cues just as we defined the speech space. Things are a little more complicated in this case, because it is not so clear what all the dimensions are, or even whether the number of dimensions is finite. If by non-speech audio we mean any audible sound different from intelligible speech, the space is indeed very large. In order to use non-speech audio effectively, we need to restrict the space. Thus, in the following, the sound space is a suitably restricted subspace of the entire space of non-speech audio.
The following enumerates a few of the dimensions we could use in constructing the non-speech component. Depending on the type of hardware available, we will have fewer or more dimensions.
We thus think of a point in this restricted subspace of non-speech audio as a distinct sound. Each channel of audio output is a point in an instance of such a subspace. Multiple channels of sound are thus modeled as a direct sum of these subspaces.
In the following, the sound space and the associated primitives for working in this space are defined assuming no restrictions on the underlying hardware. However, AsTeR restricts itself to the simpler setting provided by SPARC audio.