PURPOSE: To illustrate audio spectrograms and three-dimensional spectral surfaces.

DESCRIPTION: This demonstration uses the PC-486 with a sound card and software creating a three channel per octave spectral analysis system. With this device the standard spectrum can be viewed, but with less resolution than the FFT devices des cribed in neighboring demonstrations. This may be useful in observing vocal formant regions. However, this software allow display of audio spectrums, either in black and white gray scales or in full color, where the luminoscity or the color represents t he intensity. A nice three-dimensional spectral surface can be easily displayed, with frequency plotted from left to right, time passing from back to front, and the intensity of the sound at particular frequency ranges plotted vertically. The photograp h above is a spectral surface of a male voice singing oo-ah-ee-oo (rear to front on the plot) at a frequency of about 150 Hz. The formants are clearly visible on the computer screen.

SUGGESTIONS: You should practice before using this one in class.

REFERENCES: See equipment file for manual describing this apparatus and its operation.

EQUIPMENT: PC-486 with sound card and spectrum software.


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