text: Like pressure, this quantity is plotted on the y-axis of Fletcher-Munson contours after scaling via A- weighting.
full_question: Like pressure, this quantity is plotted on the y-axis of Fletcher-Munson contours after scaling via A- weighting. The net value for this quantity is zero in a diffuse field but is maximized in the active field. This quantity is proportional to both frequency squared and maximum displacement squared, or alternatively, it equals one-half the pressure squared over a non-electrical quantity called impedance. This quantity equals the product of particle velocity and pressure. It drops off with one over radius squared since it equals power over the (*) surface area of an imaginary sphere. The level of this quantity equals ten times the logarithm of it divided by one picowatt per square meterÂ—a reference value also known as the threshold of hearing. For 10 points, name this quantity often measured in decibels.
first_sentence: Like pressure, this quantity is plotted on the y-axis of Fletcher-Munson contours after scaling via A- weighting.
raw_answer: sound intensity [or acoustic intensity; or I; prompt on loudness or volume]