Have you ever been in the gym or in an exercise class with a human noisemaker? You know...the grunter or the screamer...that person who uses bodily noises to inform everyone within earshot that they're working hard? Yeah...I hate it too.
Don't get me wrong. I grunt when I lift sometimes. In fact, I'm far from being a silent training enthusiast and often I instruct people, especially children and teens, that our bodies need to release some of that built up energy and noise is a great way to do it. Ever go into your bedroom, lock the door, and just scream away your frustrations? There's a reason we're drawn to screaming and yelling and being loud in general when we feel overwhelmed.
That "one last rep" grunt or shout...I love that. Heck, any sound that has a noble purpose is something right up my alley. What I don't like...what I hate even...is using that God-given gift of noise to falsely advertise effort. Grunting because it'll make it sound like you're working hard is garbage. Your instructor(s) know what your best is. Don't try to dress is up in some kind of false suffering, like throwing 100 kicks in a demanding stance is really that big of a deal for you anymore. Want to impress your instructor/coach? Suffer in silence. Become annoyed with your temporary discomfort and use that to push you to a new level.
In our kids Kyokushin classes, we've been working through the virtues of Bushido and have so far spent time learning about honesty and politeness/respect. Whatever the virtue is, the theme carries over into the Teen and Adult classes, just with a different flavor.
False shouts and grunts and grimaces don't make you look good. They make you look like a liar and a cheat. Be honest with yourself. Be honest with your instructor. Again, Sensei knows what your best is. For my students, I know when you're busting your butt and when your slacking off. Keep your composure. Suffer in silence.