Chapter 2 Basic Speech Acoustics
Fundamental frequency
When the vocal folds are set into periodic vibration they create a sound, which is also
periodic
oBy periodic it means it repeats at regular intervals. There is one cycle or
period for each complete opening and closing of the vocal folds
oThis is the only case in speech where there is one-to-one direct relationship
between a physiological event of speech and the acoustic signal
Why is the rate of vocal fold vibration different from men than it is in women?
oMen have longer vocal folds with greater mass. The larger and heavier the
vocal folds the slower the typical rate of vibration
oChildren have shorter vocal folds with less mass so they have faster typical
rates of vocal fold vibration
What are some fundamental frequency values given in the book for men?
oAbout 100 Hz to 120 Hz
oIn women, about 160 Hz to 200 Hz
oIn young children, may have fundamental frequencies of 300 Hz or higher
Remember that we use the term fundamental frequency for the actual rate of vibration
of the vocal folds. So pitch refers to the perception of the fundamental frequency.
The speaker produces the fundamental frequency and pitch is perceived by the
listener.
Why is a different term used for the actual physical vibration of the vocal folds and
the perception?
oThere is not an exact correlation between the two. It takes a greater and
greater difference in fundamental frequency to effect as large a difference in
the perception—especially at higher frequencies.
If we looked at the acoustic signal of the vibrating vocal folds in fact it would be a
simple periodic wave. A sinusoid in fact.
oIt looks like a simple S shaped wave. From the baseline up to a maximum,
down to the baseline then down to a minimum and back to baseline
oFigure 2-1 is not a sinusoid. Figure 2-1 is a complex wave not a simple wave
oThe shape of this waveform is more complex than a simple up and down
sinusoid
What has happened to the sound of the vibrating vocal folds in this figure?
oIt has been ‘filtered’ or shaped by the supralryngeal vocal tract
Figure 2.1 is a vowel sound
We can’t tell which particular vowel sound just by looking at the waveform, but we
do know it is a vowel because it is a complex wave
In other words, because people have heads, we never act
