1977
John Grey's 1977 study and Max Neuhaus's work represent two sides of the same coin: the former provides scientific data on how we perceive sound quality (timbre), while the latter offers the artistic application of those perceptions in physical space.
John Grey: Multidimensional Perceptual Scaling (1977) Grey's paper is a milestone in psychoacoustics. He used multidimensional scaling (MDS) to map how the human ear distinguishes between different musical instruments. Timbre space: Grey discovered that our brain categorizes "sound color" (timbre) based on three specific physical dimensions: spectral energy (brightness), synchrony of harmonics, and "attack" (the onset of the sound). "Grey space": He created a 3D map in which similarly sounding instruments (such as a trumpet and a trombone) are physically close to each other, providing a mathematical way to quantify subjective listening.