An uneven rehearsal

Original non-fiction-style practice text.

Inside the rehearsal room, the drummers finished every passage together. Their leader, Niko, stopped the session only to adjust the distance between two players. He was pleased enough to shorten the final practice. The following morning, the group assembled in the courtyard where the performance would take place.

From the back row, the opening rhythm seemed strangely hesitant. Players who had been exact the day before now entered late. Niko was about to ask them to practise more when he walked to their position. The front drums reached him clearly, but a second, softer beat followed each strike from the stone wall behind the stage. A player listening for the cue had to distinguish the intended rhythm from its echo.

Niko moved the back row forward and turned the ensemble slightly away from the wall. He then asked everyone to watch his raised hand at the difficult entry. The next attempt held together. He restored the practice time he had removed and spent it working in the courtyard rather than returning indoors. Their earlier success had been genuine, but it had answered a narrower question than he realised: could they play together in one particular room? It had not shown what they would hear in the place where the audience would sit.

Explain why Niko’s view of the players’ late entries changes when he stands at the back of the courtyard.