A square perch, often referred to as a "square pole" or simply "perch," is an obsolete unit of land area measurement. It was historically used in some English-speaking countries, including the United States and the United Kingdom, for land surveying and property descriptions.
One square perch is equivalent to one square rod or one square pole. In terms of modern measurements, one square perch is approximately equal to 25.29285264 square meters (m²) or 0.00625 acres.
Like other obsolete units of land area measurement, the square perch has largely been replaced by more standardized systems of measurement, such as square meters and square feet, in modern times. It is rarely encountered in contemporary land transactions or legal documents.
A "sabin" is a unit used to measure the sound absorption of a material or surface. It quantifies the effectiveness of a material in reducing sound reflections within a room or space. The sabin is named after Wallace Clement Sabine, an American physicist who made significant contributions to the study of architectural acoustics.
One sabin is equivalent to one square foot (approximately 0.0929 square meters) of perfectly sound-absorbing material. In other words, if a material has a sound absorption of 1 sabin per square foot, it means that it absorbs all sound energy that strikes it, and none is reflected.
Architects, acoustical engineers, and designers use the sabin as a measurement to assess and improve the acoustic properties of rooms, such as concert halls, theaters, recording studios, and offices. By selecting materials with known sound absorption coefficients and calculating the total sabin value for a space, they can optimize the acoustic environment to reduce unwanted echoes and noise.