Humans mostly tend to ‘breathe out’ whilst speaking (or making other vocalisations). Mostly but not exclusively. So-called Ingressive Speech is quite prevalent worldwide – and not just amongst ventriloquists. Take for example, a Scottish male saying “Aye aye I ken” (“Yes, yes I know”).
[.wav audio file here]
Robert Eklund, who is Associate Professor (Docent) in Computational Linguistics at Linköping University, Sweden, provides an online resource page devoted to Ingressive Phonation & Speech – including human vocalisations like the one above, and also cheetah-purring etc etc.
For an example paper, see: Pulmonic ingressive speech: a neglected universal? in Proceedings of Fonetik 2007, 30 May – 1 June 2007, Stockholm, Sweden. TMH-QPSR, vol. 50, pp. 21–24.