"Whereas Schaeffer and Henry were working like samplers, their idea was to capture those sounds which couldn't be serially calibrated because they were too complex in character"

This quote by Luc Ferrari is referring to the work of two authors, Schaeffer and Henry, who were try out sound. They were working like samplers, which indicates they were gathering and recording sounds from the environment. Their idea was to record those sounds which could not be serially calibrated, meaning they might not be precisely determined or reproduced. These noises were too intricate in character, indicating they had a lot of different elements and subtleties that could not be quickly captured or replicated. Schaeffer and Henry were trying to capture these sounds in order to develop a more sensible and immersive musical experience. By doing this, they were pushing the borders of what was possible in music composition.