SPHSC 461
Temporal Integration and Loudness
I. Purpose
The purpose of this lab is to show how the duration of a sound affects its audibility and to demonstrate how loudness changes as the intensity of sound changes.
II. Equipment
CD player and Auditory Demonstrations CD:
Demonstration 7: Loudness Scaling (tracks 19 and 20)Demonstration 8: Temporal Integration (track 21)
III. Orientation Points
A. Review audibility curve; introduce idea that duration is an important variable.
B. Review the concept of loudness scaling — accomplished via magnitude estimation or magnitude production.
C. A two-fold change in loudness is produced by a 10 dB step in level.
IV. Lab assignment: Temporal Integration
A. Demonstration 8: Temporal Integration (track 21)
1. For each burst of broadband noise played (durations of 1000, 300, 100, 30, 10, 3, and 1 ms), count and record the number of bursts you hear. Note that each staircase is presented twice.
2. Plot each group member’s temporal integration function. Describe the function. Is its slope what you would have expected? Is there a "breakpoint" in the function?
3. Plot the group’s average temporal integration function. Indicate the range of thresholds you obtained. Is the average curve more or less similar to the expected shape?
IV. Lab Assignment: Loudness
A. Demonstration 7: Loudness Scaling (tracks 19 and 20)
1. A reference sound of broadband noise will alternate with a similar sound having a level of 0, -5, -10, -15, or -20 dB with respect to the reference sound.
2. Twenty trials will be presented. For each trial, estimate the loudness of the sound with respect to the reference sound. Make sure to give your estimates on a ratio scale: If one sound seems twice as loud as the reference, then give it a loudness estimate twice as big as you would give the reference.
3. Questions:
a. Plot each group member's loudness function, log loudness as a function of level in dB re: reference. What approximately is the slope of the line you would fit to these data?
b. What does the slope indicate about the growth of loudness? How different are the group members slopes? What would expect the slope to be?