Masking--Effects of Frequency

Imagine you are listening to the radio and the phone rings.  How loud should the ringer be for you to hear it? 

• Does the volume of the phone's ring matter? 

• Does the pitch, or frequency, of the ring matter? 

Masking occurs when one sound prevents you from hearing a second sound. Volume, measured in decibels (dB), would clearly affect how easily you could hear either sound.  Do the relative pitches of the two sounds matter?  To ask this question, you would need to vary both the pitch and the volume of the second tone.  The graph to the right shows hypothetical data from such an experiment.  The first tone, or mask, was presented with a second tone that was either higher or lower in frequency, at a range of different volumes, all softer than the mask.  The softest tone was 36 dB's quieter.  If only volume matters, you would expect to perceive two tones at a particular dB for all frequencies, as shown.  Is this truly the case? To examine this, participate in the following task.  Will your perception depend only on volume, or will pitch matter?

Adjusting your volume...

Adjust the volume of your RealPlayer console or computer speakers until you can just detect this >low, soft tone.

Taking the test...

Listen to the trials as many times as you like, and then check whether you hear one or two tones.  When you are comfortable with the task, feel free to listen only once to each trial.  After you complete the set, press the "Register" button beside the table to view your results.  Don't worry about saying "one" or "two" an equal number of times, just mark whether or you not you hear one or two tones.  Once you have completed the task, graph your results.

One tone or two?