The sentences in Figure 1 are ordinary news-like utterances read by native speakers of each language. Each panel of the figure shows the duration of successive vowels in the corresponding sentence (in milliseconds). Thus in the top panel, the first data point represents the duration of the first vowel in the word "Finding," which is about 120 milliseconds (ms) long, the second point is the duration of the second vowel in "finding," which is about 40 ms long, and so on. The key thing to notice is that adjacent vowels in the English sentence tend to differ more in duration than do adjacent vowels in the French sentence. That is, in the English sentence it is quite common for a relatively long vowel to be followed by a relatively short one (or vice versa), while in the French sentence the duration of neighboring vowels tends to be more similar. Speech researchers recently developed a way to quantify the average degree of durational contrast between neighboring vowels in a sentence, called the "normalized Pairwise Variability Index" or nPVI^2,3. It turns out that this value is significantly higher, on average, in British than in French sentences⁴. This likely reflects the greater durational disparities in English than in French between vowels in stressed and unstressed syllables⁵.

Since the nPVI can be applied to any sequence of durations, it can also be applied to a sequence of musical notes, such as a theme from a symphony by Elgar or from a piece by Debussy. In a previous study, we applied the nPVI to the instrumental music of 16 British and French composers⁶, analyzing several hundred themes from a well-known musicological sourcebook⁷. We focused on composers who lived and worked around the turn of the 20th century, as this is considered a period of musical nationalism. We found that the nPVI of English music was significantly higher, on average, than that of French music. In less formal terms, English music rhythmically "swings" more than French music, just as English speech rhythmically swings more than French speech.

Having found a parallel between rhythm in speech and music, we recently turned our attention to melodic issues. Using the same databases of speech and music, we asked if there was a difference between English and French intonation which was reflected in the music of the two nations. When studying rhythm, we had the benefit of an existing quantitative measure (the nPVI) which differentiated between English and French speech and which could be applied to music in a straightforward way. In the case of intonation, no such measure was available. Thus we devised a novel way of quantifying melodic patterns in speech, using a method which could be adapted to music.

Although the physical manifestation of melody in speech - the fundamental frequency of the voice - moves by continuous glides rather than by discrete frequency steps, some speech scientists have suggested that speech melody is perceived as a sequence of distinct syllable pitches⁸. We used a simplified method to compute each syllable's perceived pitch, based on the mean fundamental frequency of each vowel, since vowels form the core of syllables. Thus for each sentence in our database, we converted the continuous fundamental frequency contour of the sentence into a sequence of discrete frequencies which we call "vowel pitches." (Note that these pitches do not conform to any musical scale.) The top panel of Figure 2 shows the original fundamental frequency contour of the English sentence of Figure 1 and Sound Example 1. The middle panels shows the sequence of vowel pitches for this sentence: i.e. the pitch of the voice goes up from the first to the second vowel of "Finding," and then goes down for the next three vowels in "a job is," and so on.

Figure 2. The speech melody of an English sentence. The top panel shows the original fundamental frequency contour of the voice, the middle panel shows successive vowel pitch values, and the bottom panel shows vowel pitch intervals (in semitones). The sentence can be heard in Sound Example 1.

Just as one can compute pitch intervals between notes in a musical melody, one can also compute pitch intervals between successive vowel pitches in a sentence. The bottom panel of Figure 2 shows the intervals between the successive vowel pitches of the example sentence, in units of semitones. (A semitone is the pitch distance between an adjacent black and white key on a piano.) Note how the interval between the first and the second vowel of "Finding" is an upward leap of about 4 semitones, while the interval between the second vowel of "Finding" and the following vowel ("a") is a downward step of about 2.5 semitones, and so on. Unlike on a piano, vowel pitch intervals are not constrained to whole-numbers of semitones: these intervals can fall between the cracks of standard Western musical intervals.

We quantified the pattern of vowel pitch intervals for each sentence in our database, and found that the average vowel-to-vowel pitch movement was about the same size in English and French sentences (about 2 semitones). However, the intervals in French sentences were significantly less variable in size than in English sentences. Put another way, as the voice moves from one vowel to the next in a sentence, the size of each pitch change is more uniform in French than in English speech.

To see if this difference between the two languages was reflected in music, we turned to our database of turn-of-the-century composers, and examined the same set of musical themes which we had previously analyzed for rhythm. For each theme we measured the pitch intervals between successive notes (in semitones), and then computed the variability of these intervals, just as we had done for speech. Our findings paralleled what we found in speech: interval sizes in French themes were significantly less variable than in English themes. As the melody moves from one note to the next in musical themes, the size of each pitch change is more uniform in French than in English music.

Our results are shown in Figure 3, which combines our findings on rhythm and melody in speech and music. The x-axis shows rhythm (the degree of durational contrast between vowels in sentences or notes in musical themes), while the y-axis shows melody (pitch interval variability between vowels or notes). By plotting rhythm and melody together, a striking pattern emerges, suggesting that a nation's language exerts a "gravitational pull" on the structure of its music.

Supported by Neurosciences Research Foundation as part of its program on music and the brain at The Neurosciences Institute, where ADP is the Esther J. Burnham Fellow and JRI is the Karp Foundation Fellow. We thank J. Burton, B. Repp, J. Saffran & B. Stein for comments.

Figure 3. Rhythm and melody in British English and French speech and music. The x-axis shows the degree of durational contrast between successive vowels/notes in sentences/musical themes (measured using the nPVI), while the y-axis shows the variability in the size of pitch movements between successive vowels/notes in sentences/themes (measured using the coefficient of variation of absolute interval size). English data are shown in red and French data in blue. Circles represent mean values for speech or music, and lines are standard errors. English composers studied were: Bax, Delius, Elgar, Holst, Ireland, and Vaughan Williams. French composers studied were: Debussy, D'Indy, Fauré, Honegger, Ibert, Milhaud, Poulenc, Ravel, Roussel, and Saint-Saëns.

References

1. Nazzi, T., Bertoncini, J., & Mehler, J. (1998). Language discrimination in newborns: Toward an understanding of the role of rhythm. Journal of Experimental Psychology: Human Perception and Performance, 24 (3), 756-777.

2. Low E.L., Grabe, E., & Nolan, F. (2000). Quantitative characterizations of speech rhythm: Syllable-timing in Singapore English. Language & Speech, 43 (4), 377-401.

3. Grabe, E. and Low, E.L. (2002) Durational variability in speech and the rhythm class hypothesis. In C. Gussenhoven & N. Warner (Eds.), Laboratory Phonology 7 (pp. 515-546). Berlin: Mouton de Gruyter.

4. Ramus, F. (2002). Acoustic correlates of linguistic rhythm: Perspectives. In: Proceedings of Speech Prosody, Aix-en-Provence, 115-120.

5. Dauer, R.M. (1983). Stress-timing and syllable-timing reanalyzed. Journal of Phonetics, 11, 51-62.

6. Patel, A.D. & Daniele, J. (2003). An empirical comparison of rhythm in language and music. Cognition, 87, B35-B45.

7. Barlow, H. & Morgenstern, S. (1983). A Dictionary of Musical Themes, Revised Edition. London: Faber & Faber.

8. d'Alessandro, C. & Mertens, P. (1995). Automatic pitch contour stylization using a model of tonal perception. Computer Speech and Language, 9 (3), 257-288.

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