Exercise 1
AUD 613
Explore Loudness Change with Frequency for Low, Medium, and High Intensity Sounds
Place a clear ruler horizontally across the attached figure, connecting the ordinate axis markers corresponding to a variable intensity of 30 dB SPL. Now move your finger along the ruler’s straight edge across the abscissa (the variable frequency) from the left-hand end of the axis (20
Hz) through the right-hand end of the axis (16,000 Hz). Pay attention to the loudness contours you cross as you sweep your finger through the variable frequencies.
This exercise gives you an idea of your loudness perceptions of the sounds as you keep the intensity constant while steadily increasing the frequency.
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Look at the frequency region between 20 Hz and 250 Hz. How would you describe the 30 dB SPL tone relative to absolute threshold? What does this suggest about many low frequency tones?
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Now look at the 30 dB SPL ordinate axis at 350 Hz and 950 Hz. What phon contours are crossed at about those two frequencies? What does this suggest about the perception of loudness in this frequency range?
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How would you describe loudness perception between 950 Hz and 3500 Hz?
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What phon contours does the 30 dB SPL ordinate axis cross at about 8000 Hz and 10,000
Hz? What does this suggest about the loudness of the tone?

How would you describe the audibility of the 30 dB SPL tone as the frequency increases above 10,000 Hz.
Repeat the exercise, but now place the ruler horizontally across the figure connecting the ordinate axis markers corresponding to variable intensity of 60 dB SPL, which reflects a moderate intense stimulus. Again, slowly move your finger across the ruler’s straight edge, mimicking the process of keeping the intensity of the pure tone constant while increasing frequency. Notice the contour lines you cross and at which frequencies.

How would you describe the audibility of the 60 dB SPL tone at 60 Hz?

Look at the frequency region between 60 Hz and 400 Hz. What five contours are crossed? What does this suggest about loudness growth in this region?
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How would describe loudness perception between 400 Hz and 4000 Hz?

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What can we say about the magnitude of loudness perception as the frequency increases from 4000 Hz.

Is the tone at 60 dB SPL audible at 16,000 Hz?
‘Repeat the exercise one more time. This time place the ruler horizontally across the ordinate at
110 dB SPL. Slowly move your finger along the straight edge across the abscissa from left to right.

Pay attention to the loudness contours that you cross as the frequency of the variable tone is increased from 20 Hz through 8000 Hz. What contours are crossed? What does this suggest?

What happens at frequencies above 8000 Hz?
Contrast the effect of frequency on the loudness of the three pure tone levels used in this exercise. What does this tell you overall about the effect of frequency on loudness?