sound waves impacting on the human eardrum, causing fluctuations in the hair.The amplitude of the sound vibrations directly related to the perceived loudness of these waves - what it is, the volume will be felt more strongly.This, of course, simplistic interpretation.But the point is!
perception of the same sound intensity each person will have their own.Therefore, it is fair to argue that the volume - a subjective quantity.Moreover, this parameter depends on the frequency and amplitude of the sound waves and pressure waves.On the volume is influenced by factors such as the duration of the vibrations, their localization in space, timbre and spectral composition.
unit volume is called sleep (sone).1 dream corresponds approximately to the volume of muted conversation and the volume of the engine of the aircraft is 264 Sonam.By definition, a volume equal to one sleep pitch frequency 1000 and a level of 40 dB.The power of the sound, as expressed in sones has the formula:
J = k * I1 / 3, there
to - depending on the frequency coefficient, i - the intensity of the vibrations.
Due to the fact that the oscillations with different sound pressure (varying its intensity) at different frequencies may have the same volume, to evaluate its forces also used such a unit, as a background (phon).F 1 is equal to the difference in sound volume level 2 with the same frequency, for which the same loudness sound frequency of 1000 Hz will vary in pressure level (intensity) of 1 dB.
In practice, in order to specify or compare the volume, the most commonly used decibel - unit derived from the white.This is due to the fact that the increase in intensity of the sound is not in a linear relationship to the intensity of the waves, and logarithmic.1 bel is equal to a tenfold change in the power oscillation amplitude.This is a pretty big one.Therefore, for the calculation of one-tenth of its use - decibels.
Day the human ear can hear sound waves volume of 10 decibels and above.It is believed that the maximum range of frequencies available to man, equal to 20-20 000 Hz.It is noticed that it changes with age.In his youth, is best heard midrange wavelength (about 3 kHz), in adulthood - frequency of 2 to 3 kHz, and in old age - the sound of 1 kHz.Sound waves with amplitudes up to 1-3 kHz (kilohertz first) enter the area of verbal communication.They are used in broadcasting for LW and MW bands, and phones.
If the frequency is less than 16-20 Hz, such a noise is considered to infrasound, and if it is greater than 20 kHz - ultrasound.Infrasound with fluctuations in the 5-10 Hz can cause resonance with the vibration of internal organs, act on the brain and strengthen the aching pain in the joints and bones.But ultrasound is widely used in medicine.Also use it to repel insects (mosquitoes, gnats), animals (eg, dogs), birds from airfields.
To determine the volume of the sound or noise, use a special device - a sound level meter.It helps to find out what you do not exceed the maximum permissible sound vibrations magnitude that bears no danger to humans.If a person is exposed to long-wave with a level greater than 80-90 dB, it can cause complete or partial loss of hearing.This may also occur in pathological disorders of the nervous and cardiovascular systems.Safe volume is limited to 35 dB.Therefore, to preserve the hearing is not necessary to listen to music on headphones at full volume.Being too noisy place, you can use earplugs.