The Stereo Workstation
includes a Test Tone and Noise generation mode to exercise your system. The level and
frequency of the left and right channel Test Tones can be
independently adjusted. The tones can be sine wave, AM or FM, modulated to produce more
useful signals when dealing with the human perception of sound. The Workstation can
generate cosine tone bursts or continuous tones. The FM modulation plus the AM burst
modulation produce tones that have superb imaging characteristics and excellent bandwidth
characteristics for use in psychoacoustic experiments and testing. It is this kind of
tone
that is used in Computer Aided Adjustment sessions. The phase balance between the left
channel and right channel tones can also be adjusted. It is instructive to listen to the
effects of phase balance on Test Tones. Just by changing the phase balance the tone can be
located anywhere in the sound image space from left to right, however this only works for
frequencies less than about 1kHz and greater than 200 Hz. The Workstation can generate Uniform Masking Noise
(UMN) which
has the property that it can equally mask Test Tones of any frequency. The left
and right channel UMN can be
correlated or uncorrelated and the noise level and balance can be adjusted. The Workstation can also generate Flat Noise which is mathematically flat across the frequency spectrum. The
Oscilloscope or the Spectrum Analyzer can be activated to view the Test Tones graphically
on the Monitor screen.
The following image shows the Tones Mode display screen with Oscilloscope active:
This picture shows a 100 Hz tone in green for the left channel trace
and a 500 Hz tone in blue for the right channel trace. These are pure
tones since AM modulation, FM modulation, additive noise, and burst mode
are all disabled, which is indicated on screen by dark gray colored
readout labels at the bottom. |