Acoustic strategy, phonetic comparison and perceptive cues of whistled languages

Whistled speech is a complementary natural style of speech to be found in more than 30 languages of the world. This phenomenon also called “whistled language” enables distant communications in the background noise of rural environments. Whistling is used as a sound source instead of the vibrations of the vocal chords. The resulting acoustic signal is characterized by a unique functional narrow band of frequencies encoding the words. Such a strong reduction of the frequency spectrum of the original spoken voice explains why whistled speech is language-specific, relying on selected salient key features of a given language. However, for a fluent whistler, a spoken sentence transposed into whistles remains highly intelligible. That's why whistled languages represent valuable sources of information to phoneticians. This study is based on new original data collected in 7 different cultural communities or gathered during specific perceptive experiments. Whistling is first found to prolong the strategy at play in shouted voice in order to increase the possible distance of communication. Then an analysis of the linguistic behaviours of various types of whistled speech is presented, with an emphasis on non-tonal languages. Finally, whistled vowels of non-tonal languages are shown to be the reflection of the perception of formant proximitie