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 Speech Acoustics of the World’s Languages
Benjamin V. Tucker and Richard Wright
   Depending on how one counts, there are more than 7,000 languages in the world (Eberhard et al., 2019). Many languages contain unique and interesting sounds and combinations of sounds that speakers produce to convey meaning to listeners. A language may share similarities with other languages on some dimensions while also having dif- ferences along other dimensions. Because of this linguistic diversity, it is important to the understanding of speech communication, and, more specifically, sound production in the world’s spoken languages, to sample the sounds of lan- guage as broadly as possible. In the present article, we briefly discuss the diversity of the world’s languages and speech sound production mechanisms. We also discuss the impor- tance of documenting the acoustic characteristics of these sounds and the role of linguistic extinction on our ability to adequately sample the sounds of the world’s languages.1
Over the last century and a half, speech researchers have developed a reasonably good understanding of how speech sounds are produced in the vocal tract. Given this, we might assume that sampling any single language, or even a hand- ful of languages, might be sufficient for understanding speech sounds. However, even a language like !Xóõ (Traill, 1985) that is spoken in Botswana by about 2,000 speak- ers (Eberhard, et al., 2019), with 58 consonants, 31 vowels, and 4 tones, covers only a fraction of the attested speech sounds in the world’s languages. Similarly, as pointed out by Ian Catford (1977) and Björn Lindblom (1990), from an anthropophonic (human sound) perspective, the vocal tract is capable of producing a much wider variety of sounds than are used in human language (e.g., beatboxing; Proctor et al., 2013) because linguistic sounds are constrained to be efficient vehicles for communication. Therefore, as scientists, it is important that we sample languages broadly rather than
This article derives from a special issue of The Journal of the Acoustical Society of America on the Phonetics of Under-Documented Languages that was edited by Benjamin V. Tucker and Richard Wright. You can see all articles in the issue at
relying on a handful of well-documented or closely related languages from restricted geographic distributions. For his- torical and demographic reasons, linguistic diversity and the research sampling of languages is not evenly distributed across the globe.
The maps in Figure 1 illustrate the linguistic diversity of the world and both maps illustrate the uneven global distribution of languages. Figure 1A is a heat map of each country in the world showing the number of lan- guages spoken in that country, including both indigenous and immigrant languages (Hammarström et al., 2019).
 Figure 1. A: world heat map of individual countries. Colors, total number of languages reportedly spoken in each country as per Glottolog (Hammarström et al., 2019). B: world map of language location. Circles, latitude and longitude associated with an individual language as reported by Glottolog; color is associated with one of six regions (North America, South America, Eurasia, Africa, Australia, and Oceania). Where circles become difficult to distinguish represents a dense linguistic region.
   56 Acoustics Today • Summer 2020 | Volume 16, issue 2
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