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Changing Pitch and Intonation
Options
Seven speaker-definition options control aspects of the fundamental frequency (f0)
voice contour.
bf
hr
sr
as
qu
ap
pr
Baseline fall, in Hz
Nominal hat rise, in Hz
Nominal stress rise, in Hz
Assertiveness, in %
Quickness, in %
Average pitch, in Hz
Pitch range, in %
Baseline Fall (bf):
The bf option determines one aspect of the dynamic fundamental frequency contour for
a sentence. If the bf option is 0, the reference baseline fundamental frequency of a
sentence begins and ends at 115 Hz. All rule-governed dynamic swings in fundamental
frequency are computed with respect to the reference baseline.
Some speakers begin a sentence at a higher fundamental frequency, which gradually
falls as the sentence progresses. This falling baseline behavior can be simulated by
setting the bf option to the desired fall in Hz. For example, setting the bf option to 20
Hz causes a sentence's fundamental frequency pattern to begin at 125 Hz (115 Hz plus
half of bf). It fails at a rate of 16 Hz per second until it reaches 105 Hz (115 Hz minus
half of bf). The baseline remains at the lower value until it is reset automatically before
the beginning of the next full sentence (after a period, question mark, or exclamation
point). The rate of fall (16 Hz per second) is fixed, regardless of the extent of the fall.
Whenever a [ + ] syntactic symbol is included in the text (indicates the beginning of a
paragraph), the baseline is automatically set to begin slightly higher for the first
sentence of the paragraph. The baseline fall differs among speakers, and is not a good
cue for differentiating among them. As long as the fall is not excessive, its presence or
absence is hardly noticeable. See Stress and Syntactic Symbols for a complete list of
symbols.
Hat Rise (hr):
The hr and sr options determine aspects of a sentence's dynamic fundamental
frequency contour. To modify these values selectively, it is necessary to understand that
the fundamental frequency contour is computed as a function of the lexical stress
pattern and syntactic structure of a sentence.
A sentence is broken into clauses (punctuation and clause-introducing words determine
clause boundaries). Within each clause, the fundamental frequency contour rises on the
first stressed syllable. It stays at a high level until it reaches the last stressed syllable of
the clause, where it falls dramatically. This rise and fall is called the hat pattern by
linguists (jumping from the brim of a hat to the top of the hat and back again).
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