Hey mate, I think something like this should work:
PHP Code:
// We create the variable for the user name here with a max length of 32 characters
new playerName[32];
// Now we assign the name of the user to that variable
get_user_name(id, playerName, charsmax(playerName));
// Now we send the message to everyone
client_print(0, print_chat, "%s activated the following sound", playerName);
Just add it to the function that executes the sound and it should work. Replace "id" in the get_user_name function arguments with the variable holding the player executing the command.