Clubhouse co-founder Paul Davison is a bundle of energy when he joins the Microsoft Teams call from his home in California.

His high spirits contrast with the popularity of his audio-only chat app. Launched in March 2020, the app went semi-viral earlier this year before it tumbled dramatically in Apple’s App Store rankings.

“It’s been quite an 18 months,” Davison told CNBC.

Clubhouse, which was initially only available on iPhone, enables users to find and listen to conversations between people. Users join “rooms,” where friends and strangers discuss everything from cryptocurrency and politics to diets and video games. Hosts can “pass the mic” to others in the room and listeners can raise their hand when they want to speak.