Power and Loudness in The Real World
Perceived "loudness" varies logarithmically with output power (other inversely proportionate factors are; frequency, number and material of objects through which the sound waves must travel, as well as distance between source and receiver) a given change in output power produces a much smaller change in perceived loudness. Consequently it is useful and accurate to express perceived loudness in the logarithmic decibel (dB) scale.
An increase/decrease of 3 dB corresponds to a doubling/halving of power. The sensitivity of loudspeakers,rather than merely the often-quoted power-handling capacity, is important when maximum volume levels are desired. Many high quality domestic speakers have a sensitivity of 84 dB for 1 W at 1 meter, but professional speakers can have a figure of 90 dB for 1 W or even 100 dB (especially for some large-coned woofers). I.E., An '84 dB' source "speaker" would require a 400-watt amplifier to produce the same audio energy as a '90 dB' source being driven by a 100-watt amplifier, or a '100 dB' source being driven by a 9.92 watt amplifier. This does not mean a bigger speaker can produce more sound with less overall power. Just that a larger speaker can typically handle more initial power and so requires less amplification to achieve the same high level of output. This means using a speaker with a higher dB rating can be more advantageous as very high power amplifiers become impractical.
A better measure of the 'power' of a system is therefore a plot of maximum loudness before clipping of the amplifier and loudspeaker combined, in dB SPL, at the listening position intended, over the audible frequency spectrum. A good system should be capable of generating higher sound levels below 100 Hz before clipping, as the human ear is less sensitive to low frequencies, as indicated by Equal-loudness contours.
Read more about this topic: Audio Power
Famous quotes containing the words power and, power, real and/or world:
“I talk democracy to these men and women. I tell them that they have the vote, and that theirs is the kingdom and the power and the glory. I say to them “You are supreme: exercise your power.” They say, “That’s right: tell us what to do;” and I tell them. I say “Exercise your vote intelligently by voting for me.” And they do. That’s democracy; and a splendid thing it is too for putting the right men in the right place.”
—George Bernard Shaw (1856–1950)
“The preservation of life seems to be rather a slogan than a genuine goal of the anti-abortion forces; what they want is control. Control over behavior: power over women. Women in the anti-choice movement want to share in male power over women, and do so by denying their own womanhood, their own rights and responsibilities.”
—Ursula K. Le Guin (b. 1929)
“No other human being, no woman, no poem or music, book or painting can replace alcohol in its power to give man the illusion of real creation.”
—Marguerite Duras (b. 1914)
“However low and poor the taking Snuff argues a Man to be in his own Stock of Thought, or Means to employ his Brains and his Fingers, yet there is a poorer Creature in the World than He, and this is a Borrower of Snuff; a Fellow that keeps no Box of his own, but is always asking others for a Pinch.”
—Richard Steele (1672–1729)