Reducing language to rhythm: Amazonian Bora drummed language exploits speech rhythm for long-distance communication

Abstract

Many drum communication systems around the world transmit information by emulating tonal and rhythmic patterns of spoken languages in sequences of drumbeats. Their rhythmic characteristics, in particular, have not been systematically studied so far, although understanding them represents a rare occasion for providing an original insight into the basic units of speech rhythm as selected by natural speech practices directly based on beats. Here, we analyse a corpus of Bora drum communication from the northwest Amazon, which is nowadays endangered with extinction. We show that four rhythmic units are encoded in the length of pauses between beats. We argue that these units correspond to vowel-to-vowel intervals with different numbers of consonants and vowel lengths. By contrast, aligning beats with syllables, mora or only vowel length yields inconsistent results. Moreover, we also show that Bora drummed messages conventionally select rhythmically distinct markers to further distinguish words. The two phonological tones represented in drummed speech encode only few lexical contrasts. Rhythm thus appears to crucially contribute to the intelligibility of drummed Bora. Our study provides novel evidence for the role of rhythmic structures composed of vowel-to-vowel intervals in the complex puzzle concerning the redundancy and distinctiveness of acoustic features embedded in speech.

Categoricity, Variation, and Gradience in Sambla Balafon Segmental Encoding

“…I propose that these phonetic effects exert influence over surrogate speech as musicians think about the words as they play, which controls the timing of their strokes. This suggests that the timing of surrogate speech should largely mirror the timing of spoken language, a finding reported for the Bora manguaréslit log drumming tradition (Seifart et al, 2018). In the case of Bora, the authors determined that beat timing tracked vowel-to-vowel intervals rather than syllables.…”

“…Nevertheless, while the notes of the instrument are fixed, and the number of strikes (single vs. flam) is likewise a categorical feature, duration is gradient. Specifically, the timing between strikes of the balafon (interbeat durations, Seifart et al, 2018) is not isochronous and varies depending upon the word that is encoded. These gradient distinctions appear to be subconscious, since at the level of conscious encoding musicians report neutralizations where duration measurements suggest a distinction.…”

Franconian tones fare better as tones than as feet: a reply to Köhnlein (2016)

“…the mora or the rhyme, includes the syllable onset (Howie 1974, Duanmu 2000. 10 Our conjecture is 10 Further evidence for the tonally inactive status of the onset has recently been presented by Seifart et al (2018), who show that the timing of drum beats in Bora is better explained by the duration of rhyme-to-rhyme stretches than by the duration of syllable-to-syllable stretches. This implies that the beats must be timed relative to therefore that H* in Accent-2 contours cannot be downstepped, which suggests a condition on downstep: H* should have an association, ruling out downstepped Accent 2 (see (9b.ii)).…”

“…Further evidence for the tonally inactive status of the onset has recently been presented by Seifart et al (2018), who show that the timing of drum beats in Bora is better explained by the duration of rhyme-to-rhyme stretches than by the duration of syllable-to-syllable stretches. This implies that the beats must be timed relative to rhyme beginnings (or equivalently onset endings), not to syllable beginnings (or equivalently rhyme endings).…”

The “Law of Brevity” in animal communication: Sex-specific signaling optimization is determined by call amplitude rather than duration

“…The probable pressure for the informational complexity of human vocal communication might have limited the use of high-amplitude vocalizations. In parallel, the invention of artificial means of longrange communication (e.g., drumming [Seifart et al 2018], smoke signals [Turpin 1984]) could have replaced the need for long-range vocal transmission. As a pure speculation at this stage, the elimination of the amplitude constraint might have allowed human languages to reach a signal duration/signal occurrence optimization (brevity).…”