The loudness of sound is based on intensity level measured in decibels using a logarithmic scale and is relative to (a ratio of) the weakest sound the ear can hear.
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At normal atmospheric pressure, the temperature dependence of the speed of a sound wave through air is approximated by the following equation:\n\nv = 331 m/s + (0.6 m/s/C)*T\nwhere T is the temperature of the air in degrees Celsius. Using this equation is used to determine the speed of a sound wave in air at a temperature of 20 degrees Celsius yields the following solution.\n\nv = 331 m/s + (0.6 m/s/C)*T \nv = 331 m/s + (0.6 m/s/C)*20 C\n\nv = 331 m/s + 12 m/s\n\nv = 343 m
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Using spectrogram analysis, the units of measure are typically hertz (on the frequency axis) and decibels (dB, on the amplitude axis). Either may be expressed linearly or logarithmically.
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Sound is a pressure fluctuation. Sound pressure is the pressure deviation from the local ambient pressure caused by a sound wave. Sound pressure can be measured using a microphone in air and a hydrophone in water. \n\nA sound pressure level is almost always expressed in decibels compared to a reference sound pressure of 20 µPa (micropascals), which is usually considered the threshold of human hearing (roughly the sound of a mosquito flying 3 metres away). 194 is about the Theoretical upper limit of human ears called the threshold of hearing will cause physical damage, while 120-130 is called the threshold of pain and is just painful to listen to. \n\nA dogs ears operate below the threshold of human hearing. So their ears respond to sounds that ours do not. This is because of their ears sensitivity to pressure, the same way you might be able to feel a sound that is above the threshold of hearing.\n\nLoudness is the quality of a sound that is the primary psychological correlate of physical intensity. Loudness is also affected by parameters other than intensity, including: frequency (see Equal-loudness contour), bandwidth, and duration (see temporal integration).\n\nThe volume knob on a radio should be renamed Loudness not volume, for volume is the mesurment of space not intensity of pressure.\n\nLoudness is often approximated by a power function with an exponent of 0.6 when plotted vs. sound pressure or 0.3 when plotted vs. sound intensity (Stevens' power law). More precise measures have been subsequently made that show that loudness grows more rapidly (with a higher exponent) at low and high levels and less rapidly (with a lower exponent) at moderate levels.\n\nWhen sensorineural hearing loss (damage to the cochlea) is present, the perception of loudness is altered. Sounds at low levels (often perceived by those without hearing loss as relatively quiet) are no longer audible to the hearing impaired, but interestingly, sounds at high levels often are perceived as having the same loudness as they would for an unimpaired listener. This can be described by a phenomenon called Recruitment. The most common cause of sensorineural hearing loss is exposure to elevated sound levels.
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The decibel scale is used to describe the intensity or power of a sound relative to some other intensity/power level.  As you've probably learned, the difference in intensity, expressed in decibels, between a sound with intensity "I1", and a sound with intensity "I2" is:\n\ndB = 10*log(I1/I2), \n\nwhere the "log" is the base-10 logarithm.\n\nThe same relationship holds if you replace intensity with power.\n\nIf I1 is two times I2, then:\n\ndB = 10*log(2/1)\n\nThe log of 2 is 0.301029996..., so db = 10* 0.301029996 =  3.0103 ~= 3.\n\nIf I1 is ten times I2, then:\n\ndb = 10*log(10/1) = 10 * 1 = 10.
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Sound, as in sound waves?\n\nAmplitude, wavelength, pitch, frequency, longitudinal, vibration, echo, decibel, resonance.
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It's the ratio of the volume taken up by air spaces (the voids) to the total volume of a material.
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First, we must remember that sound is transmitted in the form of compression waves, or "longitudinal waves". In other words, the mechanism is through atoms or molecules (I will use the generic term "particles") bump into each other to transfer the energy. So, basically we have a series of elastic collisions where each particle bumps into the next, thereby transferring all of its energy.\n\nNow, the amount of energy being transferred is not dependent upon the frequency, but rather the amplitude of the sound wave. \n\nOn the other hand, the amount of POWER (energy per second) is related to frequency. The higher the frequency, the more often the particles bump into each other, so the more power is delivered.\n\nThe answer to your second question is that our skin cannot "feel" frequencies much above 100 cycles per second, probably less than that, due to its elasticity, it cannot resonate at higher frequencies. On the other hand, our eardrum is designed to vibrate at much higher frequencies, and in effect our ability to hear is a manifestation of our eardrum "feeling" the sound. Of course the eardrum itself is only a very small part of the process by which we hear sounds.\n\nHope this helps.
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The frequency of sound is the number of waves emitted by the source of sound.\n\nBut we judge the frequency of sound by the number waves falling in our ear drum.\n\nIf we were standing still, we will judge the actual frequency of the sound emitted by the speaker.\n\nIf we move toward the speaker, the number of waves that are falling in our ear drum is increased; the number is increased by a factor c+v/ c where c is the speed of sound and v is the speed of us toward the speaker.\n\nThe same thing happens if we are at rest and the speaker moves toward us. \n\nSuppose we move away from the speaker with the speed of sound, then we cannot hear the sound at all. If we move with a speed less than that of sound, it implies the speed of sound is more and as we are also moving we will hear only less number of waves. Thus the frequency is decreased.  This time the factor is c-v/v. \n\nThe same thing happens if we are at rest and the speaker moves away from us.\n\nThis effect is called Doppler effect.
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Goel has given you the correct answer.\n\nIf there is no damping of sound waves, sound once produced will last for ever. \n\nThe intensity of a sound wave having a frequency of 100 cycles per second, decreases by a factor of 1.015.\n\nThe intensity of a sound wave having frequency of 20, 000 cycles per second, decreases by a factor of 10^274.\n\nUltra sonic vibrations are damped so rapidly that their transmission over a distance of more than several hundred meters is completely impractical.\n\nWhen a source of sound in an auditorium is cut off the sound energy in the room does not vanish immediately. It takes certain time. This time depends upon the absorption of sound energy by the materials present in the room.\n\nThe persistence of sound in a room even after the source has been cut off is called reverberation.\n\nThe reverberation time is the time for the original intensity to fall to the audible limit.\n\nIf the reverberation time is below 0.5 second the speech is not heard in a room.\nIf the reverberation time is between 0.5 second and 3 second the speech is heard clearly.  \n \nIf the reverberation time is more than 3 second and if the time interval between consecutive reflections is less than 1/15 of a second, the sound is unclear.\n\nIf the time interval between consecutive reflections is more than 1/15 of a second, clear sound (echo) is heard.
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Two sound waves of equal frequency have a constant phase relationship so there is a constant amount of reinforcement or cancellation.  If the frequencies differ, the relative phase repeatedly varies between cancellation and reinforcement (total cancellation and reinforcement if the amplitudes are equal) at a rate equal to the difference in frequency.  The resulting sound has an apparent pitch between the two frequencies if they are close enough, or is heard as two frequencies if not, and is "amplitude modulated".  If the amplitudes are high enough, distortion in the ear results in perception of a third frequency ("difference frequency") at the modulation rate.
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Here is a somewhat accurate quick way to determine this.\n\nTake your resting hear rate x height (inches) and divide by your weight (pounds) and finally multiply by 1.75%.
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Don't give up too easily on the sound wave thing.  Graphic equalization.  Sound is measured in hertz (Hz) & Kilo Hertz (KHz), Kilo being the metric measure for 100.  Start with the low tones - long wavelengths, low number of hertz.  Move up the tone scale. As the tones get higher pitched the smaller the wave lengths - increased number of hertz. Super highs, like cymbals are in the kilohertz range and so on.  It's an everyday thing that everyone can relate to .  When you hear a siren go by the tone is lower as it approches and higher, faster, as it passes you and back to lower tones as the object receeds.  Good luck.
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You'll need something which measures the amplitude and frequency of the sound waves to 'see' a difference in the noises.  You can probably calculate a trigonometric function based on one particular wave within the measurement, but it won't hold true as the sounds fluctuate at random.  Possibly, you could even program a computer to calculate a random value between set parameters to account for this fluctuation.\nI'm not a math person.  Can't help you much more than that.
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The amp is found by subtracting the maximum of the wave by the minimum of the wave, and dividing that number by 2.
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A subwoofer is a type of loudspeaker dedicated to the reproduction of bass frequencies, typically from about 20 Hz to about 200 Hz. It is difficult for small loudspeakers to reproduce frequencies below 40 Hz, especially above 100 dB, and so it is often advantageous to use a loudspeaker intended specifically for this task.
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First, variables:\nsay "x" is the intensity of sound measured in watts per square meter and "h" is the smallest sound a human can hear at 10^-12 watts per square meter. So the decibel measurement of the sound heard in x is 10*Log(x/h)\n\nsince it is based on a comparison its easier to use 2 different sounds.\n\nLoud Music is 100dB, Intense thunder is 120dB. Initially it would seem that this isnt that much of a difference. 20dBs is a whisper, but on calculation:\n\n1)100=10*log(x1/10^-12)    120=10log(x2/10^-12)\n\n2)100/10=log(x1/10^-12)    120/10=log(x2/10^-12) \n\n3)(10^10)= x1/10^-12                 (10^12)=x2/10^-12\n\n4) x1 = (10^10)(10^-12)              x2=(10^12)(10^-12)\n\n5) x2/x1 = 1/.01 = thunder is 100 times louder than loud music\n\nand now back to work
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Measure the speed of sound by help of an echo, a stopwatch and a tape-measure. (depending on temperature it is about 430 m/s.\nRepeat your measurements at least 10x and have the average.\nGood luck\n\nTh