PSYCH 3A03 Lecture Notes - Psych, Root Mean Square, Sound Power

• School: McMaster University
• Department: Psychology
• Course: PSYCH 3A03
• Professor: Paul Faure

Document Summary

Sound pressure (p) is proportional to air particle velocity. Air particles vibrate due to input force. Power (p): rate of energy transfer through medium. Units of energy = joule (j); 1j = 1nm. Power is the rate at which work is accomplished. The watt was named after james watt who invented the stem engine. 1 watt = 1 j/s = 1 nm/s. Energy is the ability to do work. Power: rate of energy transfer through a medium. Power is the rate at which sound is accomplished. Power and energy are proportional to each other, but they are not equivalent measures. Acoustical energy is transmitted outward form a point source in an expanding spherical wave form. To measure its acoustic power (j/s), we would have to integrate over the entire spherical surface. Often we are only interested in the amount of power that acts upon or passes through a certain, smaller pre-defined area, such as one square meter.