Instructions
Open the "Users" menu from the cross-media bar. Select "Create Name" to enter a new name for the user. Select "OK."
Log in to the new user from the "Users" menu. Select "Yes, I want to create a new account" and enter the requested information. Enter the email address and password of the console's master account to authorize the new account's creation.
Sign in to the email account associated with the PS3's master account. Open the "PLAYSTATION(R)Network Account Registration for a Child" email. Follow the included instructions to confirm and authorize the new account.
Log in to the master account on the PS3. Select "Playstation Network," then "Account Management" from the cross media bar. Select "Manage Sub Accounts" to bring up the sub account management screen.
Select the new account you just created. Turn on the "Restrict chat with other users" option.
Log in to the new account whenever you want to play a game without voice chat.