No Rehearsal, No Score, Two Continents. Go.

Nearly 8,000 miles (12,800 km) separated these four singers. Two in Los Angeles, one in Canberra, one in Melbourne. No rehearsal. No score. No agreed-upon arrangement.

Somebody just said "let's sing Happy Birthday to Rosie," and they did.

One voice leads. Nobody chases anybody.

In our first video from this session, the singers followed a reference track and heard each other only from a previous take. This one works differently. Alex conducted live. The other three heard her and, just as important, watched her hands and lips. She was the reference, and she was creating it in the moment.

The catch, and it is a real one: Alex heard only herself. That is the price of being the leader. Sound cannot arrive before it departs, so if she waited to hear the group, they would wait to hear her, and the whole thing would spiral. Break the loop and it works.

Very, very helpful, one said. The playback sync adjusted the timing correctly. Another pointed at what it means for real repertoire: for choral music with all its push and pull, being able to follow a conductor live is the thing.

Then there is the part we did not plan. With no rehearsal, four singers on two continents improvised harmony on the fly. Afterward somebody had to ask whether anyone had actually sung the melody.

Somebody had.

You will hear their comments after the song.

The singers

• Alex Siegers, Venice, California (director and alto) — alexsiegers.com
• Cody Christopher, Dickson, ACT, Australia (tenor)
• Gabbi Coenen, Sherman Oaks, California (soprano)
• William Darbyshire, Clifton Hill, VIC, Australia (bass)