Wednesday, September 1, 2010

336. Did Music Originate as a Behavioral Adaptation? -- 7: Speech

In her recent Scientific American article, Speaking in Tones, psychologist Diana Deutsch describes some remarkable research, by herself and others, revealing some unexpected and very exciting links between speech and music. For example, despite many years in which it was assumed they were controlled by two completely different regions of the brain, "Psychologists, linguists and neuroscientists have recently changed their tune . . . as sophisticated nueroimaging techniques have helped amass evidence that the brain areas governing music and language overlap." The two regions are so interconnected that "an awareness of music is critical to a baby's language development and even helps to cement the bond between infant and mother" (p. 37).
This overlap makes sense, because language and music have a lot in common. They are both governed by a grammar, in which basic elements are organized hierarchically into sequences according to established rules. In language, words combine to form phrases, which join to form larger phrases, which in turn combine to make sentences. Similarly, in music, notes combine to form phrases, which connect to form larger phrases, and so on. (pp. 38-39)

I'm a bit skeptical regarding the many examples of baby-mother interaction she provides, because, like so many others in her field, and in cognitive science generally, she assumes that all babies and mothers interact similarly, based on research typically limited to American and European subjects. Before attempting to universalize such evidence, it's important to compare it with evidence from non-Western societies, as well as various indigenous groups from a wide range of different world areas.

The above reservations do not apply to her most remarkable and exciting results, regarding a completely unexpected and indeed very surprising correlation between absolute (or "perfect") pitch and tone language. She made the astonishing discovery that among students who had received musical training by the age of five, fluent speakers of Mandarin, a tone language, were far more likely to have absolute pitch than a comparable group of students who grew up with English or some other nontone language. We're talking a huge difference, of 92% of "very fluent tone language speakers," as opposed to only 8% of English speakers. To determine whether the correlation were primarily genetic rather than linguistic, she tested East Asian students who grew up speaking a non-tone language and discovered that they too scored only about 8%. The correlation seems definitely associated with tone language rather than genetic inheritance.

Another important discovery concerns the pitch sensitivity of tone language speakers generally. It's always been assumed that the pitches of tone language are relative and not absolute, yet Deutsch learned that
not only were Vietnamese and Mandarin speakers very sensitive to the pitches that they hear, but they can produce words at a consistent absolute pitch. . . We found that their pitches were remarkably consistent: when compared across days, half of the participants showed pitch differences of less than half a semitone (p. 42).

In the next post, I'll explain why I attach such importance to these results.

2 comments:

Diana said...

I agree wholeheartedly with the surmise that human language most likely began as tone language – and that it included absolute pitch as a feature. More specifically, I’m suggesting that with increasing communication across linguistic subcultures, speakers and listeners have been forced to transpose their uttterances in order to understand each other. As a result, in several linguistic subcultures the absolute pitch component of tone language has become degraded, so as to approach pitch accent language – which in its turn in some subcultures has become degraded so as to approach nontone language. For example, over the last couple of decades, it appears, Shanghainese, which had been highly tonal, has lost much of its original pitch characteristics and is now considered closer to pitch accent language. It seems to be no coincidence that Shanghai is a major port, where people speaking many different languages and dialects interact strongly. I also understand that in Japan the pitch accent component of language is gradually being eroded – at least in major cities.

I see this as a real pity, since absolute pitch is in principle very useful as a vehicle for communication. The pitch characteristics of speech survive transmission over long distances much better than, say, vowel quality. Absolute pitch levels can convey a great deal of information, and should in principle be easy to process. However, it seems that absolute pitch is bundled in with other features of speech, so that - at least where the ability to associate pitches with verbal labels is concerned - it is subject to a similar, basically inflexible, critical period as occurs for these other features.

So far I’ve confined my research to East Asian tone languages, since this is logistically the easiest way for me to proceed, particularly as there is a large East Asian community in San Diego – however African languages should indeed provide important information.

Diana Deutsch
Department of Psychology, UCSD

DocG said...

Thanks so much for your comments, Diana. I'm really pleased to learn that we're in agreement on the historical status of tone language and the significance of absolute pitch.

As you have so elegantly demonstrated, tonogenesis would, in at least some instances, have to involve much more than the emergence of vague contrasts between relatively high, mid and low vowels to substitute for non-tonal contrasts in an earlier version of a language. If absolute pitch is involved, as it apparently is in Mandarin, then it would be very difficult to explain how this remarkable ability could have emerged out of thin air during a transition from a non-tonal language.

Whether absolute pitch can be associated with linguistic tone as a general rule, is therefore an extremely important question, which can only be answered by additional research along the same lines.

"As a result, in several linguistic subcultures the absolute pitch component of tone language has become degraded, so as to approach pitch accent language – which in its turn in some subcultures has become degraded so as to approach nontone language."

Interesting. For me, it's much easier to imagine how pitch sensitivity could be lost over time than the opposite, which would require the development of a heightened sense of pitch along with all the other, purely linguistic, changes that would need to be accounted for.

It's possible, however, that there are two different types of tone language: one, essentially a survival from the original form; the other, a development from a language that had long ago lost its tonality and later regained it, possibly due to the influence of a neighboring language. If this is the case, then one would expect that languages of the first type would have retained their association with absolute pitch while those of the second type might have lost it. Does this make sense?