Hearing: Sound Localization

 

Objective:

To explain in short essays or diagrams how the ear and the brainstem determine the location of sounds, at the level of 85% proficiency for each student.

 

In order to achieve this objective, you will need to be able to:

  1. Explain how the ear and the brainstem assist in determining the location of sounds.
  2. Examine the anatomical organization of the cochlear pathways responsible for sound localization.

 

Materials:

Group Supplies

1 blindfold

8 pairs of chopsticks

8 post-it notes

1 meter stick

Descriptions of cochlear pathways are available as a supplement: Cochlear Pathways

 

Methods:

This experiment examines the ability to identify the location of a sound.

  1. Organize a group of 12 students with the following members:
    1. 8 noisemakers
    2. 1 listener
    3. 1 pointer
    4. 1 data recorder
    5. 1 group discussion coordinator.
  2. Clear a 2.5 x 2.5 m area of the classroom floor.
  3. The eight noisemakers should be positioned around the listener in a circle. Each noisemaker should be at least 2 m away from the listener. All noisemakers should be equidistant from the listener.
  4. The pointer should give each noisemaker a set of chopsticks and demonstrate how to strike the chopsticks together to make a consistent sound.
  5. The noisemakers should practice making sounds with the chopsticks so that the same intensity of sound is made by each. If possible, the listener should be out of the room as the noisemakers practice. If this is not possible, the listener should be positioned in the room in such a way that he/she hears as little as possible of this practice session.
  6. The listener should be blindfolded and seated in the center of the 2.5 x 2.5 m cleared area within the circle of noisemakers as shown in Figure 1. At no time during the activity should the listener move his/her head.
  7. The pointer should randomly point at one of the noisemakers to make a sound with the chopsticks.
  8. Without moving his/her head, the listener should point in the direction believed to be where the sound originated.
  9. The data recorders should record on the data chart in Figure 2 which position the subject pointed.
  10. Repeat Steps 8-10 until each noisemaker .
  11. The data recorders will tally the correct and incorrect responses for each position and read these data out loud for the members of the group. Group members will record this information in their journals.

 

 

Results:

 

 

 

Experimental Location

Subject (Name)

Trial

1

2

3

4

5

6

7

8

 

1

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

Discussion:

  1. Did the listener point correctly to the sound at each of these locations: 3? 7? 1? 5? 2? 8? 4? 6?
  2. Did your group have a lot of correct responses for locations 3 and 7? 1 and 5? 2, 4, 6, and 8? Did you see a similarity to these locations?
  3. How might you explain the patterns of responses in each of the following locations:
    1. 3 and 7 compared with 1 and 5?
    2. 3 and 7 compared with 2, 4, 6, and 8?
    3. 1 and 5 compared with 2, 4, 6, and 8?
  4. Did you notice if the listener hesitated longer in responding to sounds coming from some locations than from others? How might you explain these differences?