So, for example, you find nasality in posed laughter, that kind of "ha ha ha ha ha" sound that you never get, you could not do, if you were laughing involuntarily.
Tekonaurussa esimerkiksi on nasaalisuutta, sellaista "ha ha ha ha ha" -ääntelyä, jota ei koskaan synny, tai jota ei  voi tehdä, kun nauraa tahattomasti.