Frequency

A speech signal consists of many frequencies, each of which varies in time, and is associated with a different task in communication.

For example, the fundamental frequency of the signal conveys the speech melody, which is used in English to structure the utterance (a kind of acoustic punctuation) and to convey various kinds of speaker attitude. The presence of a fundamental frequency presupposes that the speech signal is voiced.

Tasks:

• Use Praat to examine the fundamental frequency of the examples which you have been analysing so far.
• Which speech segments have a fundamental frequency, and which do not?
• Try to identify shapes in the fundamental frequency contour, and discuss what their function in communication might be.

The overtones of this signal follow the general contour of the fundamental frequency, but have different strengths. These strength - or energy - patterns are shown in the spectrum of an interval in the speech signal. A series of spectra, representing the frequency properties of a sequence of intervals in the speech signal, is called a spectrogramme

Tasks:

• Use Praat to examine the spectrum of selected positions in the speech signals which you have been analysing.
• Look at the spectrogram of the speech signal. Which patterns are associated with which kinds of speech sound?

Intonation

Intonation is the use of the fundamental frequency (corresponding to the speech melody) in order to

• indicate completion or continuation points in the utterance,
• indicate accentuation or focus in the utterance,
• indicate boundaries between parts of the utterance,
• indicate speaker attitudes and emotions.

Accent

Accent is an ambiguous term, sometimes meaning a variety of pronunciation associated with a dialect region or social class.

Here it means the use of fundamental frequency, syllable length and intensity to indicate the degree of importance (in some sense) of a constituent of an utterance.