In this paper, the authors argue against the findings presented in Hay & Bauer (2007) which suggest a positive correlation between population size and phoneme inventory size in languages. In order to do so, they highlight some methodological issues in the previous study, as well as other studies addressing similar questions. To address these issues, the authors conducted their own study using a larger and more representative sample of phoneme inventories drawn from the PHOIBLE knowledge base, and applied a more rigorous statistical analysis using a hierarchical mixed model. The results indicate that correlations between population size and phoneme inventory size are quite small when compared to differences among language family groups, and that the phoneme-population relationship fluctuates around zero between families, suggesting that any relationship between population and phoneme inventory size does not generalize to language as a whole. The author concludes that the correlations seen between population and phoneme inventories are likely to be artifacts, and do not find compelling reason to consider population size as a potential causal factor in the development of phonological systems.

In the field of bioacoustics, the Acoustic Adaptation theory suggests that variation in vocalization across different species can be accounted for by the acoustic properties of different habitats. Here, the researchers test consonant- and vowel-heaviness in human languages against various environmental variables in order to examine the theory's potential application to our own species. The authors identify a significant negative correlation between consonant heaviness and temperature, precipitation, and tree cover, and some positive correlation with rugosity and elevation as their most important findings, while acknowledging the potentially influential roles of migration and demographic factors in producing this relationship.

This article examines the universal tendency for languages, regardless of their historical relationships, to develop similar words for mother and father on the basis of nursery forms. Findings suggest that Ma, Na, Pa, and Ta are significantly more common sound classes denoting the mother or father.

This article adds nuanced findings to the previous generalization that high sonority of the vowel explains its more frequent use in warmer climates. The authors find that “speakers in warm-climate languages make more use of the so-called “sonorant” consonants, that is, consonants with some of the qualities of vowels” (123).

This study examines whether language construction, specifically the number of consonant-vowel syllables, will be related to the environment and literacy of a society. Empirical analysis suggests that consonant-vowel syllables are more common in warmer climates and less common in written languages.

This article presents a reanalysis of a previous study on language rhythm and consonant-vowel syllables by Ember and Ember (2000). Communicative efficiency, climate, baby-holding, literacy, and mean number of syllables per word were all considered as factors in consonant-vowel syllable use.

Munroe and Fought attempt to add new perspective to Ember and Ember's (2007) assertion that certain environmental features help to predict mean sonority levels in speech. This article discusses the other possible elements such as word length that might raise the level of communicative efficiency.

The author investigates whether geographic factors--namely high elevation or 1500 m+ above sea level (reduced atmospheric pressure)-- impact the production, use, and ubiquity of ejective phonemes in eight non-contiguous language clusters. It is suggested that increased use of ejective phonemes has a physiological benefit: the reduction of water vapor loss via exhaled air. Evidence is presented in support of the hypothesized geographic-phonetic linkage.

This article focuses on environmental and social explainations for variations in sonority. As expected, results suggest that climate, vegetation density, and sexuality are associated with sonority.

This article explores the possible relationship between the cultural evolution of language, music, and genetic variation beyond the level of language families. Due to their linguistic diversity, the authors use a sample of 14 Northeast Asian societies with matching information on their music, genetics, and linguistic patterns. The variables measuring language are lexicon, phonology, and grammar. Then, the authors compare each variable's relationship to music and genetic variation. The results only show a significant correlation between grammar and genetic variation.