The Stuart and Steinway pianos described in chapter 1 were recorded in a controlled sound field created by an array of eight microphones.

Describing a sound field by specifying sound pressure levels for a number of points in a room represents a view point oriented toward the listeners, or recording devices at those points.²¹⁷

The microphone positions in a 180° array defined the sound field, see fig 3.2 below. It was found that the direction in which the sound radiated from the pianos affected the qualities of its tone and it loudness. For example, the tonal quality and sound pressure level of a piano note recorded at microphone 6 (mic6) could be found to be different to the same recorded note at microphone 2 (mic2). The evaluation of the amplitude levels and the direction of its strongest (loudest) and weakest (softest) radiated qualities was also made possible in the 180° microphone array. The direction and projection of the radiated sounds of each piano was found to be noticeably different and therefore was considered to be a consequence of piano design.

^{217     4}Meyer,3.