Volume of sound: the difference between dream, background and decibel

Sound waves, affectingtympanic membrane of the person, cause fluctuations of hairs. The amplitude of these sound oscillations is directly related to the perceived loudness of these waves - the higher it is, the more loud the sound will be felt. This, of course, is a simplified interpretation. But the essence is clear!

Perception of the same sound strength in eachman will be his own. Therefore, it will be justly asserted that loudness is a subjective magnitude. In addition, this parameter depends on the frequency and amplitude of the sound oscillations, as well as the wave pressure. The volume of the sound is influenced by factors such as the duration of the oscillations, their localization in space, timbre and spectral composition.

The sound volume unit is called a sleep (sone).1 sleep roughly corresponds to the volume of the muffled conversation, and the volume of the aircraft's engines is 264 sleeps. By definition, 1 sleep is equal to the volume of the tone at 1000 and the level of 40 dB. The power of sound, expressed in sones, has the formula:

J = k * I^1/3, here

k is a frequency-dependent coefficient, i is the intensity of the oscillations.

Due to the fact that oscillations with different soundpressure (differing in their intensity) at different frequencies can have the same loudness of sound, to evaluate its strength is also used such a unit as the background (phon). 1 F is equal to the difference in the volume levels of 2 sounds with the same frequency, for which the same loudness sounds with a frequency of 1000 Hz will differ in the level of pressure (intensity) by 1 decibel.

In practice, in order to indicate or compareloudness, most often use decibel - the derived unit from white. This is due to the fact that the increase in the strength of sound does not occur in a linear dependence on the intensity of the waves, but in the logarithmic. 1 wh is equal to a tenfold change in the force of the amplitude of the oscillations. This is a fairly large unit. Therefore, for calculations use its tenth part - decibel.

During the day, the human ear can hear soundwaves with loudness from 10 decibels and above. It is considered that the maximum range of all frequencies available to a person is 20-20 000 Hz. It is noticed that it changes with age. In youth, it is best to hear mid-frequency waves (about 3 KHz), in adulthood - frequencies from 2 to 3 kHz, and in old age - sound at 1 KHz. Sound waves with an amplitude of up to 1-3 KHz (the first kilohertz) enter the zone of verbal communication. They are used in broadcasting on DV-and SV-bands, as well as in telephones.

If the frequency is less than 16-20 Hz, then such a noiseis considered infrasound, and if it is more than 20 KHz - ultrasound. Infrasound with oscillations of 5-10 Hz can cause resonance with the vibration of internal organs, affect the work of the brain and intensify aching pains in the joints and bones. But ultrasound has found wide application in medicine. Also with its help frighten off insects (mosquito, mosquitoes), animals (for example, dogs), birds from aerodromes.

To find out the volume of sound or noise,a special instrument is used - the noise level meter. It helps to find out whether the sound oscillations exceed the maximum permissible value, which does not pose a danger to man. If a person is exposed to waves with a level exceeding 80-90 dB for a long time, this can cause total or partial hearing loss. At the same time, pathological disturbances can occur in the nervous and cardiovascular systems. The safe volume is limited to 35 dB. Therefore, to save your hearing, you should not listen to music at full volume in your headphones. Being in a too noisy place, you can use earplugs.