Welcome to the forum. I'm not sure what you mean. If someone or something gets "a big round of applause" then of course people can hear it. When lots of people clap, it's quite loud therefore it must be audible. How would you use "a big round of applause" metaphorically?
I agree with emsr that an actual big round of applause would be audible. It is possible to say that someone deserves a big round of applause without there actually being any applause.