Acoustic+Vocabulary

The pressure variations caused by sound waves in air are called sound pressure. The lowest sound pressure level which can be heard is 0 dB, known as the hearing threshold. The highest level which can be tolerated is called the pain threshold and is around 120 dB.  Materials and structures with the ability to take up the sound energy and convert it into other forms of energy. They improve room acoustics by removing sound reflections, thus reducing the noise and the reverberation time.  The physicist Wallace Clement Sabine (1869-1919) created in Riverbank, west of Chicago, the well known Sabine formula (T=0,16V/A), showing the relationship between reverberation time (T s), room volume (V m³) and the amount of absorption (A m²).  For example, speech, scraping chairs, humming ventilation, traffic, machinery and equipment, sound from corridors, adjoining rooms, playgrounds.  RASTI is an objective way of measuring speech intelligibility. It is measured at two frequencies, 500 and 2000 Hz, by placing a loudspeaker, which transmits sound from the location of the person speaking, and a microphone where the listeners are situated. (See also STI).
 * Sound pressure level (dB) **
 * Sound absorbers **
 * Sabine **
 * Background noise (dB) **
 * Rapid Speech Transmission Index (RASTI) **