To determine if critical bands, as determined by masking, are the same
for all frequencies.
To learn to test for limits.
To design your own experiment
Critical Bands - Review from material in class
How effectively a noise masks a tone depends not so much on the loudness
of the noise but the match between the frequencies of the noise and the
There is a region around the frequency that is trying to be detected
where noise can act as a masker.
Noise outside this band is ineffective as a masking stimulus.
Question: Are these critical bands always the same size for every
Below is our graph from the class critical bands experiment
Note how for the 1200 Hz tone, the masking stays about the same until the
frequency of the noise is less than 100 Hz.
This suggests that we can place that critical band at between 30 and 100
This is a send of finding the limit or size of the critical band and an
example of what is needed to answer the question posed for th experiment.
In this experiment you will ask some question about critical bands.
You will be asked to design your own experiments to conduct this test.
Independent Variable(s): the variable(s) the experimenter manipulates
Dependent Variable: the variable the experimenter measures
Control: Change only one thing at a time.
In this experiment, the IV and DV will be decided upon by you.
IVs: These will depend upon the question that you want to ask.
DV: this depends upon what you need to observer and the method that you
Your task is to develop this experiment so that you can learn something
about critical bands.
Your design can be adjusted as you go to make sure you get a good answer,
though you need a well structured experiment to begin with.
This freedom is often part of research in many areas of science.
However, in many psychology experiments, all of the conditions have to be
set up before the data collection begins because of the nature of testing
groups of subjects.
Since psychophysics tests individuals, and the few of you are easily
recollected, you can make some adjustments on the fly.
The inability to answer the question of this lab report will lead to a
significant negative impact on the grade for this lab. Remember you
may need to add new conditions to test. Give yourself and your
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