| ISLE | Chapter 11
| Sound Localization Experiment
In order to localize an object in space, we must know if it is to the left or right of us, whether it is in front of or behind us, and whether it is above or below us. That is, we must be able to localize sound in three-dimensional space. The azimuth refers to the left-right or side-to-side aspect of sound localization. Elevation refers to the up-down dimension of sound localization, and distance refers to how far a sound is from us, and whether it is in front of or behind us.
On land, we are rather good at determining if a sound is to the left or the right.
In this experiment, you can determine your ability to determine if a sound is to the left or the right. Your threshold in this case, is how much a sound is to the left for you to hear that the sound is to the left. In this experment, a 0 sound will sound direction ahead of you. A positive number moves the sound to the left and a negative number moves the sound to the right. These numbers represent the relative intensity of the sounds (gain). So a number of 1 means the sound is full intensity in the left ear and off in the right ear. A number of -0.5 means the sound is full intensity in the right ear and half intensity in the left ear. You will need headphones for this experiment.
To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.
On this tab you can adjust the type of stimulus and the various parameters of the motion of the stimulus to see how this might effect the aftereffect. The settings include the following:
Frequency: the frequency of the tone, in Hertz (Hz) or cycles per second.
Tone Duration: how long the tones in the experiment will play, in seconds.
Gain: the relative intensity of the sound (1.0 is full intensity and 0 is that the sound is off).
Play: allows you to play the current version of the standard tone.
Reset At the top of the settings page is a Reset button. Pressing this button restores the method settings to their default values.
On this tab you can adjust how the method will work. The settings include the following:
Number of Levels of Direction of Sound: How many steps there are in the staircase (series).
Number of Staircases: How many staircases (series) will be presented (always an even number).
Minimum Value of Direction of Sound (gain): the most right the relative gain for the sound. A value of -1 is full right where
the sound is full on in the right ear and full off in the left ear. A value of 0 the gain is the same in both ears.
Maximum Value of Direction of Sound (gain): the most right the relative gain for the sound. A value of 1 is full left where
the sound is full on in the left ear and full off in the right ear. A value of 0 the gain is the same in both ears.
Reset At the top of the settings page is a Reset button. Pressing this button restores the stimulus settings to their default values.
First, put on headphones and make sure you have the ears properly aligned. On the Experiment tab, press a space button or the button on the screen to start the experiment. A tone will be played. Click or press yes (or press the 'z' key) if you hear to the left of where you are looking (or press the '/' key) if you do not hear the tone to the left. When the experiment has been completed, you will instructed that you can view your results.
You data will presented on this tab where the trials will be on the x axis and the direction value of the stimulus will be displayed on the y axis. To see your threshold, which is the average of the cross-overs, click the button that says Show Threshold. To display the trial by trial data, click the Show Data button.
Change the settings below to alter the stimulus parameters in this experiment.