Tutorial How to Handle Speech – Summer 2003
Acoustic Phonetics Picture Book (June11th)
Spectogram:
Term for a graphic presentation that combines time, amplitude (intensity) and
frequency.
Waveform/Oscillogram:
Common term for a graphic presentation of sound pressure (intensity) variations over
time. It is used to record the wave form. It transforms the change in energy into
electric current changes (Volt)
Tutorial How to Handle Speech – Summer 2003
Intensity:
The instrumentally measurable factor corresponding to the loudness of a
sound. It is derivable from the amplitude or amount of increase in air pressure and
can be defined as the average rate of sound energy falling on a unit area.
Intensity is a physical property of sounds and is dependent on the amount
of energy present. Perceptually, there is a fairly close relationship between
physical intensity and perceived loudness.
Frequency of vibration is the number of cycles per second (measured in Hertz). The
vibration of for instance a pendulum can be displayed as a sine wave in a graph that
plots vibration (displacement) against time. When the wave meets the axis for the
second time, it has completed one cycle respectively the pendulum has swung left
and right and is back in its neutral position. A sound consists of many different
frequencies being a result of complex vibration. Briefly said frequency refers to the
vibration involved in the production of a sound in a specific period of time.
Tutorial How to Handle Speech – Summer 2003
Formants are the peaks of energy visible in a spectrogram. These peaks of energy
are produced by tract resonance. The information-bearing formants are numbered
upwards from the lowest in frequency (F1, F2, etc.). They function in acoustic
analyses as indicators for the distribution of energy on the frequencies. Therefore
they are essential parameters in the acoustic description of sounds. Not all five
formants are visible in every sound.