Both musicians and non-musicians can perceive bitonality

Take a listen to this brief audio clip of "Unforgettable."

Aside from the fact that it's a computer-generated MIDI performance, do you hear anything unusual?

If you're a non-musician like me, you might not have noticed anything. It sounds basically like the familiar song, even though the synthesized sax isn't nearly as pleasing as the familiar Nat King Cole version of the song. But most trained musicians can't listen to a song like this without cringing. Why? Because the music has been made "bitonal" by moving the accompanying piano part up two semitones (a semitone is the difference between a "natural" note and a sharp or flat). Here's the original, unaltered piece:

Can you tell the difference? A 2000 study led by R.S. Wolpert found that non-musicians couldn't distinguish between monotonal and bitonal music played side-by-side. Meanwhile musicians found artificially-created bitonal music to be almost unlistenable. For most non-musicians, if they heard anything wrong with the clips, they typically said they were being played too fast, or mentioned some other unrelated concept.

But Mayumi Hamamoto, Mauro Bothelo, and Margaret Munger (AKA Greta) wondered if years of musical training were really necessary for non-musicians to hear bitonal music. Bitonality is actually a bit controversial in the world of music, and it can be a little hard to define. In principle, there's a difference between bitonality and just playing or singing off-key, but in practice, the difference may not even exist. Advocates of bitonality like to point to the works of composers like Milhaud, Bartók, Prokofiev, and Strauss. These composers deliberately wrote in two different musical keys. But how is that different from occasionally or regularly writing dissonant chords? After all, all the same notes can be written using any musical key. To be truly bitonal, advocates say the two separate parts must unfold independently in different keys. This results in a distinctive "crunch" when the music is played. The separate question is, is this noticeable? Wolpert's work shows that it is, at least for trained musicians.

Hamamoto's team replicated Wolpert's study by playing altered and original clips of familiar songs like the above example to three groups of undergraduates: "Musicians" with more than 5 years of training, "Amateur Musicians" with 1 to 5 years of training, and "Non-Musicians" with less than a year of training. There were 14 students in each group. Musicians were significantly better at noticing that the modified clips were bitonal or "out of tune."

Next, everyone was given brief training session, where instead of modifying monotonal music to be bitonal, some of Milhaud's music originally intended to be bitonal was modified to be monotonal. Here's an example bitonal piece (Milhaud's "Botafogo"):

After hearing the clip and seeing it identified as bitonal, the students were told

Notice sometimes there is a "crunch" in the sound. This should sound somewhat unpleasant and feel like it shouldn't be that way.

Then they listened to a manipulated version of the same clip:

Again, they were told this clip was monotonal and directed to notice how the sound seems smoother and more pleasant (to my mind, it's not nearly as interesting as the original -- but that wasn't part of the study). Next they were trained with feedback, listening and identifying clips until they could accurately label four in a row. This took just a few minutes.

Finally, the respondents were tested on four new clips, all songs by Milhaud. This graph shows the results:


As you can see, for all the songs except "Ipanema," the students were quite accurate at identifying both bitonal and monotonal songs (error bars are 95 percent confidence intervals). More important, however, was that there was no significant difference in the results for Musicians, Amateur Musicians, and Non-Musicians. All three groups fared equally well.

The authors conclude the identifying bitonal music isn't a matter of years of musical instruction; it can be achieved with just a brief training session. In fact, the Non-Musicians took no longer than Musicians to complete the training session, so years of experience don't even help with learning about bitonality.

It also may suggest that the controversy about whether bitonality actually exists may not be warranted. If nearly everyone can hear the difference, then it's probably a genuine musical phenomenon.

Note: More of the clips from the study can be found on Greta's website here.

Hamamoto, M., Bothelho, M., & Munger, M.P. (In press). Non-musicians' and musicians' perception of bitonality. Psychology of Music. DOI: 10.1177/0305735609351917

More like this

Listen to these two musical excerpts and note any differences you discern: Ave Maria, version 1Ave Maria, version 2 (Source: courtesy of Mayumi Hamamoto and Kyota Ko) If you're a typical nonmusician, you will probably notice some sort of difference between the two excerpts. Maybe one seems to be…
[originally posted April 6, 2005] Listen to these two musical excerpts and note any differences you discern: Ave Maria, version 1Ave Maria, version 2 (Source: courtesy of Mayumi Hamamoto and Kyota Ko) If you're a typical nonmusician, you will probably notice some sort of difference between the two…
If you've had a lot of musical training, you can probably tell the difference between a major and minor key. If you haven't had much training, even after having the difference explained to you, you're still not likely to be able to make that determination. Listen the following clip. It plays the…
Listen to these two short music clips. Music Clip 1Music Clip 2 Now, can you identify the musical style of each clip? If you said "Classical," you're technically only correct for the first clip. The second clip is actually in the Romantic style (bonus points for identifying the works and composers…

It's hard to believe that someone would -not- find the first example horrible to listen to.

Really, nasty stuff...

By Janice in Toronto (not verified) on 20 Jan 2010 #permalink

...and as if to illustrate the point (relative to Janice), I listened to the first several seconds of the first two clips repeatedly and could clearly hear a very slight difference in the pitch of the piano between them. But despite noting the difference, I didn't find either of the pieces to be particularly good or bad relative to each other.

Instead, I found the synthetic saxophone to be grating...

It occurs to me that perhaps since musicians and non-musicians alike can detect the differences with some practice, the distaste for the bitonal is a bit of a cultural one? Non-musicians hear slight differences, but perceive it as stylistic whereas musicians hear the differences as 'breaking the rules'?

I actually preferred the bitonal version of Unforgettable, myself...but that's partly because i'm sick of the song and i've been listening to too much modern music to start with. While "smooth jazz" radio listeners cringe, I think *real* jazz musicians and listeners wouldn't mind more experimentation along those lines. :)

I suppose how off the bitonality feels to the average listener (as opposed to one with a musical education, even if they don't play/sing) depends on the differences between the keys. When bitonality was making its big "debut" on the stage, it was often in works by Sibelius (Symphony 4) and Stravinsky (Petroushka), where the keys competing weren't just different, they were off by a tritone.

Contrast that with a simple offset like a piano piece that Bernstein plays in his 6th of the Harvard Lecture series, where one hand is in D and the other in G, and it "mostly" fits - the odd note on the melody hand doesn't stick out as strongly as a result. I believe some of Satie's pieces are like that as well, but I can't recall.

There's also the fact that while not explicitly described as bitonal, in a sense anything in a blues scale with its blue-notes being different when going up vs coming down, is going to have inherent bitonal moments. Since much of rock music is based on those scales, and also on modes beyond the typical major-minor, the average listeners' ears are likely more attuned to some forms of bitonal music than they might have thought given a clinical definition of it.

Not to say there aren't pockets of tonality-only ("Country?") music listeners, but on the whole, I think we're just no longer as easily shocked by music as we were 120 years ago, when Debussy's Faun sparked a critical riot about "crazy modern music".

By Joe Shelby (not verified) on 20 Jan 2010 #permalink

I'm with NJ, the synthetic sax is so much worse than the bitonality of a normally monotonal song.

By marciepooh (not verified) on 20 Jan 2010 #permalink

I'm not a musician at all, but the bitonal versions both sounded slightly "off" on first listen--I wouldn't have said tempo, couldn't put my finger on it at all. After reading and repeated listenings, neither version of "Unforgettable" sounds particularly good, though the bitonal one is the worse one and it sounds like the sax is what's off, not the piano. Whereas with "Botafogo", repeated listenings just make the original version sound more and more wrong.

Yes, well, for Unforgettable, raising the accompaniment a whole step is a horribly bad choice. All those natural 11ths against tonic and dominant chords! There are many other bitonal options that would work much better. As a composer/jazz musician, I have to wonder if the choice of raising the accompaniment a whole step was deliberately chosen to sound as bad as possible? If you lower the accompaniment a whole step, then you transpose the melody to the upper extensions of the original chord progression, exploiting lydian-chromatic relationships a la George Russell. I would wager that the result would be imperceptible to non-musicians, and would doubtless please a significant portion of the musician audience.

You can't just slam any two old keys together. You really need to be aware of tonal relationships -- how the vertical intervals between the melody in one key will play against the implied upper chord extensions of the functional harmony in the second key.

(In fact, one neat little trick I use in my own improvisations is to play off of a D major scale over a tonic C major chord. It's a very pleasant way to end a song.)

Also note that in the lovely little Milhaud sample, the two voices are not only in two keys, but they exploit different tonal movement within those keys -- it's not two parallel chord progressions as in Unforgettable. That allows you to play around with exactly where the crunches will occur, using the same kind of tension/release patterns found in monotonal music.

But I'm not surprised that you could quickly train non-musicians to recognize bitonality. Every musician I know was once quickly trained to recognize bitonality.

I'm not a musician, though I do have some musical gifts similar to those of my siblings, a couple of whom are musicians. Both parents were somewhat musically inclined as well. The bitonal version sounded 'off' to me, or as I'd call it 'disonant' in some way, and not really likeable but then again I'm used to listening to modern music and I hear disonance being used as an effect, or a device, on purpose in order to say something with music, so I guess it would be tolerable for a while provided it was effective in achieving the desired result by the composer, but if all the music sounded like that, I'd probably grow fatigued or annoyed with it pretty quickly.

Not a musician; had several years of piano lessons when I was a kid, have done a good deal of choral singing, family very appreciative of music, have listened to classical music all my life, have a good ear (but not perfect pitch).

Bitonal "Unforgettable" sounded to me like a modern jazz version; didn't think there was anything "wrong" with it but didn't like it much. Preferred monotonal version. Listening to the first bar of each one after the other, instantly evident the key of the piano part was different.

Milhaud, bitonality of first version was obviously intentional; monotonal version was just meaningless.

Would have had to listen several times more intently to identify/define the differences precisely.

By Swift Loris (not verified) on 20 Jan 2010 #permalink

I'm not an experienced musician but I found the first clip completely unlistenable. It hurt. (The second one's bad but it at least sounded "right".)

Both versions of unforgettable sound bad to me. If you want to know why run this through google translate (it's swedish):stråksektionen är ändrad i andra versionen.

Actually, the first clip sounded much more interesting to me. I disagree with people who say that it's "unlistenable." To like or dislike bitonality is a personal matter, the matter of whether one has decided or not to free his/her ears from the regular constraints of what is "pleasant" and what is not. There a few moments in the first clip which I think expose some very eerie and effective dissonances, a kind of interesting otherworldly disjointed feeling.

I'm actually quite shocked to hear the revelation that non-musicians can't hear the difference between bitonality and monotonality. I wonder how accurate these same test subjects would be if they were merely to identify a singer who is singing out of tune (with the accompaniment).

Bitonality definitely exists. It's very naive to think of it as merely writing in dissonant notes once in a while, especially when the two keys are in a dissonant interval apart. This is because both keys are consistent in their dissonances. But again, for the casual non-musician listener who normally doesn't bother much to truly listen rather than just hear music, it's just dissonance.

Detecting the difference is one thing. Making a value judgment is wholly different, and I argue is invalid on its face.

I'm not surprised that both musicians and non-musicians can pick bitonal music. Tonal music is inherent to every society. It's fundamental. It is in nature. We're used to hearing it, and anything else will sound strange, unpleasant or experimental to us. so bitonality, unless manipulated to explote unusual modal characteristics, like one of the posts above pointed out, sounds un-natural and just about anyone can pick it. It's like getting two pictures of a tree. one green and one blue. it's going to be easy to pick. Non-musicians may not be able to pick the difference between the keys, but they will pick that something is different, and will most likely say that something is out of tune.

I'm not a professional musician, but grew up in a keen-amateur family (and was choral singing before I started school). With that predominantly classical group-music background in mind, the first clip actually registered as physically painful in my right ear - I could only endure 10-15 seconds in a go. My boyfriend, who has more formal training in musical theory than me, but starting at a rather later age, merely registered it as unusual and not to his taste.

By stripey_cat (not verified) on 21 Jan 2010 #permalink

Maybe I have too much musical training. The first clip just sounded like "new music" to me.

By Epistaxis (not verified) on 21 Jan 2010 #permalink

I'm was a pro musician for a long time, and I got so tired of hearing requests for Misty that I learned to play it in E in the left hand and E-flat in the right. Pretty much everyone, musician or not, realized that it was not quite right :-).

I'm a music teacher and I find the assertion that "bitonal music doesn't exist" to be blatantly wrong and unstudied. It doesn't surprise me at all that non-musicians are able to discern bitonality.

Keith, I know a former concert pianist who visited a friend's apartment with a piano against the wall. Next door was another pianist with another piano against the same wall. When the neighbor would practice Chopin, the professor would mimic him a semitone higher, following exactly his frustrated starts and stops.