| ISLE | Chapter 13
| Experiment: The Octave and Tone Similarity
Pitches get higher as frequencies go up, but there is another important dimension of pitch that is highly relevant to music: the octave. The octave is the interval between one note and a note with either double the frequency or half the frequency of that note. This is a physical definition: A frequency of 200 Hz has octaves of 100 Hz below it and 400 Hz above it. Psychologically, we hear similarities between these doubled or halved frequencies. In musical terms, we refer to them by the same note name, but at different octaves. Thus, even though notes at 200 and 220 Hz are more similar in pitch, we hear notes at 200 and 400 Hz as being alike in a way that notes at 200 and 220 Hz are not.
In this experiment you will be presented two tones and asked to judge how similar they are. This is a variation on a magnitude estimation experiment. If two tones are very similar give a rating of 100, the more different they sound, give a lower number.
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:
Gain: the the intensity of the tones.
Tone Duration: how long the tones in the experiment will play, in seconds.
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 Repetitions: How many times each stimulus will be presented.
Reset At the top of the settings page is a Reset button. Pressing this button restores the stimulus settings to their default values.
On the Experiment tab, press a space button or the button on the screen to start the experiment.
A tone will play with text indicating that stimulus is a '100' and then a second stimulus will be played.
After the second tone stimulus has been played, a box will appear for you to type your judgement.
Rate how similar the two sounds are. A rating of 100 means they are the same and lower numbers mean they
are less similar. You may use your keyboard or the buttons on the screen.
When you have finished all of your trials, you will instructed that you can view your results.
You data will presented on this tab. On the x-axis will be the different frequencies of the second tone. On the y-axis will be the similarity rating. To display the data for each trial click the Show Data button.
Change the settings below to alter the stimulus parameters in this experiment.