More on "tone-deafness"

There was some doubt as to whether the "tone-deafness" test I linked to Monday really tests for amusia. The defining trait of amusia is the inability to discern the difference between different musical pitches. So here's a test that might generate a more clear-cut result. The following track plays five sequences of five notes. In every case, four of the notes are the same. The only note that ever varies is the second-to-last note. Ideally, these sequences would be played in a random order, but for a quick-and-dirty test, I'm going to gradually increase the pitch of the fourth note in the sequence. Your task: listen to the recording and indicate when you notice that the fourth note is different from the rest of the notes in a sequence.

Let's make this a poll:

This test was inspired by an experiment by Krista Hyde and Isabelle Peretz, who in 2004 compared a group of people with tone-deafness (amusics) to a group of people with normal music perception. Listeners were presented with sets of tones like the one you just played, and in every case were simply asked if the fourth tone was different from the last one. Here are the results:

The pitch of the fourth tone was systematically varied. A 100-percent variance is equal to a full musical step -- the difference between a natural note and a sharp, or between a B and a C on the scale. As you can see, when the pitch difference was 50 percent or less than a full musical step, then amusics were significantly worse at noticing the difference.

In the sample I created above, the fourth note in the first sequence was the same as the rest. In the second sequence, it was higher by 25 percent of a full step. In the third, it was 50 percent higher; in the fourth, it was a full step higher; in the fifth, it was two full steps higher. So, if you didn't notice the difference in the second or third sequence, you may have some symptoms of amusia (or you might have bad speakers, or just a problem hearing certain pitches).

Hyde and Peretz's test was better than mine, of course, because it was random, and because it tested a range of pitches. They also conducted a similar test for rhythm, to see if amusics also had a rhythm deficit. There was no significant difference in the rhythm scores between amusics and people with normal music perception.

But is amusia a real condition, or can people learn to perceive pitch differences over time? Hyde and Peretz were able to give a definitive answer over the short term: no. Take a look at this:

Over the course of the experiment, people with normal music perception gradually improved their accuracy, but performance of amusics remained stubbornly low.

This data can also explain why amusics typically don't have difficulty understanding language: the pitch differentiation required is much coarser than in music. In English and French, for example, to indicate that a statement is a question, speakers increase the pitch at the end of the statement (think of the difference between saying "we're going to the store" and asking "we're going to the store?"). But this pitch change is usually larger than 7 musical steps, easily perceivable by everyone in the study.

Curiously, even though amusics showed no difference in rhythm perception, most amusics have difficulty keeping musical time and dancing. Hyde and Peretz suggest that this may be due to the fact that not all pitch changes are perceived by amusics, so parsing out a rhythm becomes a more difficult problem.

If you had difficulty perceiving all the differences in the sample above, do you also have difficulty keeping time with music or dancing? Let us know in the comments.

Hyde, K.L., & Peretz, I. (2004). Brains that are out of tune but in time. Psychological Science, 15(5), 356-360.