The chimpanzee has well-developed aryepiglottic folds which allows him to vocalize not only upon expiration but also upon inspiration, which for man is strenuous and unpleasant.

• 黑猩猩有发展良好的杓状会厌声带，那可以让牠不仅在吸气时能发音、在吐气时也能（这对人类来说是费力且另人讨厌的）。