Assessing respiratory contributions to f0 declination in German across varying speech tasks and respiratory demands

International audienceMany past studies have sought to determine the factors that affect f0 declination, and the physiological underpinnings of the phenomenon. This study assessed the relation between respiration and f0 declination by means of simultaneous acoustic and respiratory recordings from read and spontaneous speech from speakers of German. Within the respective Intonational Phrase unit, we analysed the effect of the number of syllables and voiceless obstruents. Both factors could influence the slope of either f0 declination or rib cage movement. If respiration and f0 declination are related physiologically, their relationship might also be modulated by either one or both factors. Our results show consistently for both speech tasks that the slope of the rib cage movement is not related with f0 declination when length and consonant content vary. Furthermore f0 slopes are generally shallower in spontaneous than in read speech. Finally, although a higher number of voiceless obstruents yielded a greater rib cage compression, it did not affect f0 declination. These results suggest that although f0 declination occurs in many languages, it might not have a purely physiological origin in breathing, but rather reflects cognitive processing which allows speakers to look ahead when planning their utterances

Energy flows in gesture-speech physics: The respiratory-vocal system and its coupling with hand gestures

Expressive moments in communicative hand gestures often align with emphatic stress in speech. It has recently been found that acoustic markers of emphatic stress arise naturally during steady-state phonation when upper-limb movements impart physical impulses on the body, most likely affecting acoustics via respiratory activity. In this confirmatory study, participants (N = 29) repeatedly uttered consonant-vowel (/pa/) mono-syllables while moving in particular phase relations with speech, or not moving the upper limbs. This study shows that respiration-related activity is affected by (especially high-impulse) gesturing when vocalizations occur near peaks in physical impulse. This study further shows that gesture-induced moments of bodily impulses increase the amplitude envelope of speech, while not similarly affecting the Fundamental Frequency (F0). Finally, tight relations between respiration-related activity and vocalization were observed, even in the absence of movement, but even more so when upper-limb movement is present. The current findings expand a developing line of research showing that speech is modulated by functional biomechanical linkages between hand gestures and the respiratory system. This identification of gesture-speech biomechanics promises to provide an alternative phylogenetic, ontogenetic, and mechanistic explanatory route of why communicative upper limb movements co-occur with speech in humans. ACKNOWLEDGMENT

Stabilizing Forces in Acoustic Cultural Evolution: Comparing Humans and Birds

Learned acoustic communication systems, like birdsong and spoken human language, can be described from two seemingly contradictory perspectives. On one hand, learned acoustic communication systems can be remarkably consistent. Substantive and descriptive generalizations can be made which hold for a majority of populations within a species. On the other hand, learned acoustic communication systems are often highly variable. The degree of variation is often so great that few, if any, substantive generalizations hold for all populations in a species. Within my dissertation, I explore the interplay of variation and uniformity in three vocal learning species: budgerigars (Melopsittacus undulatus), house finches (Haemorhous mexicanus), and humans (Homo sapiens). Budgerigars are well-known for their versatile mimicry skills, house finch song organization is uniform across populations, and human language has been described as the prime example of variability by some while others see only subtle variations of largely uniform system. For each of these species, I address several questions related to variability and uniformity: What is the typical range of variation? What are the limits of variation? How are those two issues related? And what mechanisms underlie variability and uniformity? In chapter 3, I investigate a potential domain of uniformity in budgerigar warble: the segment. Segments, units divided by acoustic transitions rather than silence, have been largely ignored in non-human animal communication. I find that budgerigars can achieve a high degree of complexity and variability by combining and arranging these small, more stereotyped units. Furthermore, I find that budgerigar segment organization is not only consistent across independent budgerigar populations but is consistent with patterns found in human language. In chapter 4, I investigate variability in house finch song. I present data showing that house finches learn sound patterns which are absent in wild house finch populations. These data suggest that cross-population variation in house finch song is narrower than what is permitted by the house finch song learning program. Finally, in chapter 5, I focus on human language, the most well-described communication system. Here, I research a sound pattern that is absent in the majority of known languages. I find that the rare pattern has independently developed at least six times. In every case, the historical pathway which led to the rare pattern was the same. The historical development in these six linguistic lineages suggests that the overall rarity of the sound pattern is the result of acoustic similarity. These data illuminate the evolutionary forces that give rise to, and limit, variation. The results of this dissertation have wide-ranging implications, from necessary revisions of linguistic theories, to understanding epigenetic interactions, to the application of evolutionary theory to complex behavior. While these projects within the dissertation are all different, evidence from all three projects support the following claims: (i) cross-population commonality is not evidence for what a species is able to learn; (ii) peripheral mechanisms have a strong influence in limiting cross-population variability; and (iii) high degrees of variation can emerge from uniform traits