(Reuters) - U.S. social audio app Clubhouse launched a feature on Thursday to let users virtually wave at friends inside its audio-only chat app to show they are open to a private chat, in a move to expand beyond public rooms that can have thousands of listeners. Clubhouse, which pioneered the “social audio” feature that has since been copied by Facebook and Twitter, wants to enable users to have private chats, Co-Founder and Chief Executive Paul Davison told Reuters. “A lot of people know us for bigger conversations, but the reason people stay so long is they’re finding their friends and meeting new people,” he said in an interview. Users of Clubhouse, which is backed by venture capital firm Andreessen Horowitz, can “wave” at friends online in the app and a private audio chat room will open when a person accepts the wave. The user can then invite more contacts into the private room, or choose to open the chat to the public, Clubhouse said.