Speech Recognition for Smart Homes
481
Most command-and-control applications have a small vocabulary size (0 to 50 words),
reflecting the operations required to control the equipment. For example, commands for
controlling the lights might include 'on', 'off', the location, and perhaps a few more words,
depending on what additional operations are available. In addition the device being
controlled should be identified (for example 'please turn on the bathroom light' is made up
of a framing word 'please', an operation 'turn on', a location 'bathroom' and a device 'light').
Usually there is a direct mapping between the word or phrase and its semantics, i.e. the action
to be carried out or the meaning to be associated with the words. However, more complex
commands can be managed through a set of alternatives, where the vocabulary is restricted
and known, such as week days or times of the day. As the number of alternative wordings
increases, the task of listing all possible combinations and associating them with a given set of
actions become unmanageable and so a grammar syntax is required that specifies, in a more
abstract way, the words and phrases along with their permissible combinations.
