ime with a time in the past
                  test.gain.exponentialRampToValueAtTime(
                      0.1, 0.5 * context.currentTime);
                  test.gain.exponentialRampToValueAtTime(0.9, 1.0);

                  reference.gain.exponentialRampToValueAtTime(
                      0.1, context.currentTime);
                  reference.gain.exponentialRampToValueAtTime(0.9, 1.0);
                })
                .then(() => context.resume());

            source.start();

            context.s