A non-metric unit of sound absorption used in acoustical engineering. One sabin is the sound absorption of one square foot of a perfectly absorbing surface--such as an open window! The sound absorption of a wall or some other surface is the area of the surface, in square feet, multiplied by a coefficient which depends on the material of the surface and also on the frequency of the sound. These coefficients are carefully measured and tabulated. The unit honors Wallace Sabine (1868-1919), a Harvard University professor who founded the systematic study of acoustics about 1895. Sabine used this unit, which he called the open window unit (owu), as early as 1911