The speech rate may be adjusted to provide a fast talking voice or a slower voice for more complex spoken content.
The property may have a numeric value assigned to indicate how many words should be read per minute. This would be an average value on the grounds that some words may take longer to pronounce than others. The speech rate can be specified as a floating point value for very fine control over the speech rate.
There are also a set of keywords so you can specify a generic absolute value. These are the keywords that are supported:
Speech rates can be adjusted relative to a parent or containing element object. Assuming a speech rate is defined for a parent object, then you can use the relative speech rate keywords slower and faster.