New study shows initial consonants of words are systematically lengthened in various languages

Speech is a continuous stream of acoustic signals, yet humans can segment words from one another with astonishing accuracy and speed. To understand how this is possible, a team of linguists analyzed the duration of consonants at different positions in words and utterances across a diverse sample of languages.

They found that word-initial consonants last on average 13 milliseconds longer than their non-initial counterparts. The diversity of languages ​​in which this effect has been observed suggests that it may be a species-wide pattern and one of several key factors that allow speech perception to distinguish word onsets in the speech stream.

The work appears in Nature Human Behavior.

Distinguishing between words is one of the most difficult tasks in decoding spoken language. Yet humans do it effortlessly, even when languages ​​don’t seem to clearly indicate where one word ends and the next begins. The acoustic cues that facilitate this process are poorly understood and understudied in the vast majority of the world’s languages. Now, for the first time, comparative linguists have observed a pattern of acoustic effects that may serve as a distinct marker across languages: the systematic lengthening of consonants at the beginning of words.

Researchers from the Max Planck Institute for Evolutionary Anthropology, the CNRS Laboratory for Structure and Dynamics of Languages ​​(SeDyL), Humboldt University of Berlin, and the Leibniz Center for General Linguistics (ZAS) used data from the new DoReCo corpus because it combines two features: first, it covers an unprecedented linguistic and cultural diversity of human language, with samples from 51 populations from all inhabited continents. Second, it provides precise temporal information for each of the more than one million language sounds in the corpus.

“DoReCo’s global coverage is crucial for discovering species-wide patterns in human language, given the immense cross-linguistic diversity of languages,” says lead author Frank Seifart, a researcher at CNRS in Paris and HU Berlin and co-editor of DoReCo.

Lengthening of initial consonants in words: a potentially universal linguistic trait?

“We initially expected to find evidence contradicting the hypothesis that word-initial lengthening is a universal linguistic trait. We were very surprised when we saw the results of our analysis,” says first author Frédéric Blum, a doctoral student at the Max Planck Institute for Evolutionary Anthropology, who initiated and led the study. “The results suggest that this phenomenon is indeed common to most languages ​​in the world.”

Strong evidence of lengthening was found in 43 of the 51 languages ​​in the sample. The results were inconclusive for the remaining eight languages.

The authors conclude that lengthening may be one of several factors that help listeners identify word boundaries and thus segment speech into distinct words, along with other factors, such as articulatory reinforcement, which have not been studied in detail so far.

In the current study, some languages ​​also showed a shortening effect after pauses at the beginning of an utterance. This is consistent with the authors’ conclusion, as there is no need for additional cues for word boundaries in the presence of pauses.

This study advances our understanding of acoustic processes common to all spoken languages. By focusing on non-WEIRD (Western, European, Industrialized, Rich, and Democratic) languages, the researchers hope to expand our knowledge of cognitive processes related to speech that transcend individual populations.