Sabin (unit)

{{short description|Unit of sound absorption}}

{{Other uses|Sabin (disambiguation){{!}}Sabin}}

File:The sabin explained.svg

In acoustics, the sabin (or more precisely the square foot sabin) is a unit of sound absorption, used for expressing the total effective absorption for the interior of a room. Sound absorption can be expressed in terms of the percentage of energy absorbed compared with the percentage reflected. It can also be expressed as a coefficient, with a value of 1.00 representing a material which absorbs 100% of the energy, and a value of 0.00 meaning all the sound is reflected.{{sfn|Moore|1979|p=35}}

The concept of a unit for absorption was first suggested by American physicist Wallace Clement Sabine, the founder of the field of architectural acoustics. He defined the "open-window unit" as the absorption of {{convert|1|sqfoot|m2}} of open window.{{sfn|Moore|1979|p=35}} The unit was renamed the sabin after Sabine, and it is now defined as "the absorption due to unit area of a totally absorbent surface".{{sfn|Moore|1979|p=35}}

Sabins may be calculated with either imperial or metric units. One square foot of 100% absorbing material has a value of one imperial sabin, and 1 square metre of 100% absorbing material has a value of one metric sabin.

The total absorption {{mvar|A}} in metric sabins for a room containing many types of surface is given by

$$A\; =\; S\_1\; \backslash alpha\_1\; +\; S\_2\; \backslash alpha\_2\; +\; \backslash ldots\; +\; S\_n\; \backslash alpha\_n\; =\; \backslash sum\; S\_i\; \backslash alpha\_i\; ,$$

where {{math|S₁, S₂, ..., S_n}} are the areas of the surfaces in the room (in m²), and {{math|α₁, α₂, ..., α_n}} are the absorption coefficients of the surfaces.

Sabins are used in calculating the reverberation time of concert halls, lecture theatres, and recording studios.{{sfn|Davis|Davis|1975|p=168}}