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.
比如说，你会发现假笑中的鼻音， 那种“哈哈哈哈哈”的声音。 那是你从未发出过的声音， 你在不由自主的笑声里做不到这样。