Watts per meter squared, there's a huge range of human hearing. ![]() Hear such a soft sound, 10 to the negative 12 "Why in God's name did the physicist have "to put logarithm in here? "This scare me." This used to scare me too. Spread one watt over the entire land area of Germany,Ībout three times over, and still it's intense enoughįor the human ear to hear. This one watt be spread over and still be intense enoughįor the human ear to hear it? What do you think? Football field? I don't know, a city? No, it turns out. How diluted could one watt be spread over? How large of an area could If you have one watt, howīig could you make this area? How, spread out. If you have one watt, how big of an area? A watt isn't really that much. Through the square meter, your ear would still be able What this says is thatĮven if only one trillionth of a joule per second passes This is one trillion ofĪ watt per meter square. Than that, a human ear that's healthy shouldīe able to detect it. What that means is this is the softest possible sound you can hear. This 10 to the negativeġ2 watts per square meter represents the threshold of human hearing. This part of the equation is my favorite. This gives you an idea of how much energy per second pass throughĪ certain amount of area. How many joulels of sound energy per second pass through the one square meter? That would be the number of watts per meter squared which ![]() If you asked how many joules per second pass through that one square meter. The power that passes through that area will be, how many joules? If you figure you how many joules pass through this one square meter. This doesn't have to beĪn actual physical object. Power's in, what? Power measure going to watts. You got your ear and a sound wave, say, is coming toward your ear. What this means, think about it this way. In Physics, intensity is defined to be the power divided by the area. If you didn't multiply byġ0, you'd have the bel scale but this is multiplied by 10. The fact that this is the Deci-bel Scale and Somewhere reader just in volume because we're going to The number of decibels and we abbreviate decibel Logarithm, base 10 of I divided by 10 to the negativeġ2 watts per square meter. This is the scale that we use to figure out the loudness of a sound. It will live on with the deciBel.I'm going to tell you about the Decibel Scale. Throughout the 20th century, the Bell name was ubiquitous. ![]() Quite a lot was named after Alexander Graham Bell. INCREASE IN POWER LEVELS (WATTS) Formula is dB=10*log(P1/P2) DeciBels Output Signal StrengthĪTTENUATION OF AMPLITUDE (VOLTS or AMPS) Formula is dB=20*log(A1/A2) DeciBels Output Signal Strength A hundred miles away, the sound level reached more than 170 dB, deafening everyone who survived. In 1883, the volcano on the Indonesian island of Krakatoa erupted. Loud thunder is approximately 110 dB, and 120 dB borders on the threshold of pain. A normal conversation is typically from 60 to 70 dB, and a noisy factory from 90 to 100 dB. One Bel is when the output signal is 10x that of the input, and one deciBel is 1/10th of a Bel.Ī whisper is about 20 dB. A deciBel is the logarithm of the ratio of the two levels. Created in the early days of telephony as a way to measure cable and equipment performance and named after Alexander Graham Bell, deciBels (dBs) are a relative measurement derived from two signal levels: a reference input level and an observed output level. One deciBel is considered the smallest difference in sound level that the human ear can discern. Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005 deciBelA unit of measurement of the loudness or strength of a signal.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |