degradation
A reduction in quality or performance of a communications channel.
deterioration
The gradual loss of data stored by a speech-recognition results object. The information in a results object can occupy a significant amount of memory, so an engine developer may permit the object to discard data automatically as time passes.
dictation grammar
Defines a context for the speaker by identifying the subject of the dictation, the expected style of language, and what dictation has already been done.
digital-audio format
Audio format controlled by binary or numeric data.
digital-audio stream
Continuous audio data received from or sent to an audio device.
Digital Signal Processor (DSP)
A general-purpose multiprocessor tailored to a particular type of operation. Applications involving communications, compression, and audio are more efficiently performed on a DSP than on the host computer.
diphone
A sound consisting of two phonemes: one that leads into the sound and one that finishes the sound. For example, the word "hello" consists of these diphones: silence-h h-eh eh-l l-oe oe-silence.
diphone concatenation
The text-to-speech engine concatenates short digital-audio segments and performs intersegment smoothing to produce a continuous sound.
discrete speech
Every word must be isolated by a pause before and after the word—usually about a quarter of a second—in order for the engine to recognize it.
DTMF (Dual Tone Multi-Frequency)
Touch-tone or push-button dialing. Pushing a button on a telephone keypad generates a sound that is a combination of two tones, one high frequency and the other low frequency.