Interactivity
Interactivity is the hallmark of AI. The high degree of
interactivity can be illustrated using the lesson on tone
detection in noise as an example. This particular interactivity
was designed to teach about the concept of the auditory critical
band. It does so by allowing the students themselves to
replicate the psychoacoustic studies that were originally
performed to document the frequency-analysis capabilities of the
ear.
The main screen shown here
gives the student control of the signal-generation parameters
relevant to this experiment through the sliders associated with
each piece of equipment in the block diagram. A sine oscillator
generates a continuous sine wave; the two sliders under the
oscillator allow variation in the frequency and the amplitude of
the sine signal, current values of which are displayed to the
right of the sliders. The sine signal passes through a switch
that controls the on-time, the interstimulus interval (ISI) and
the rise/fall (R/F) of the pulsing signal. The masking noise is
created by the noise generator, whose amplitude parameter is
controlled. The noise is bandpass filtered through a filter
whose center frequency and bandwidth are controllable. The out
put of this filter is measured by the level meter and is then
mixed with the signal. The sum of signal and noise are monitored
for clipping and delivered to one-channel of the computer’s
audio output device. The graphic icon suggests that earphones
should be used for listening.
This setup will generate a tone signal pulsing on and off
continually against a bandpass noise background. For any set of
stimulus parameters a listener can adjust the signal’s level so
that the signal is at detection threshold. If this measurement
is made as the noise bandwidth is varied, the results should
describe the classic critical bandwidth finding.
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