Information Cascades in a Karate Class

In any typical karate class, when some move is repeated, you can hear the exclamation throughout the students on the tenth repetition. When students first learn, they are taught to say something like 'kiah' with an emphasis on the ah! However, as you observe the more experienced students, only a few of them use this form of exclamation. The large majority tends to yell out a 'huh' or 'hah' with a deep, guttural sound.

Who taught them this? Why did they change from the original kiah? In part, the students are developing their own styles and techniques for going about the karate moves. But why this sound, 'huh'? The sensei leading the class still yells kiah! in the examples. My guess is that one or twu students in the class brought this exclamation from experience with another class. As other students observed their unique sounds, they followed in the same pattern, as expected in any information cascade. The rest of the students abandoned their own prior technique in order to adopt the new, seemingly more successful form of exclamation.