Olle Engstrand & Lennart Nordstrand, ‘A new phonetic interpretation of /h/ in Swedish’. Journal of Phonetics 12, 195-206, 1984.

Abstract

While utterance-initial Swedish h-sounds display an interval containing characteristically smoothed-out voice pulse ("breathy voice" or "murmur"), this effect does not appear in initial vowels. We have carried out and evaluated a set of experiments to see if conditions on voice onset manner (‘smooth vs. abrupt voice onset’) are necessary and sufficient to enable listeners to hear an h-sound or a vowel at the beginning of utterances such as Hanna and Anna. That hypothesis was essentially corroborated by the data, while the presence vs. absence of initial aspirative noise turned out to be perceptually negligible at noise levels observed in natural speech. The result has implications for questions concerning the perceptual constraints on /h/ and its distribution in the world’s languages, particularly the infrequent occurrence of syllable-final /h/.