The sound intensity

We know that air particles vibrate by a sound source to be charged. From experience we know that close to the source (eg a loudspeaker) the sound louder than further away from the source. This is because the vibration circles get bigger as the sound source moves away. Thus becoming more and more air particles in the collision process. The energy must always be dealt with more air molecules, as shown in the figure.

 

 

Sound Intensity is a measure of the energy consumed by the sound per second on a surface of 1 m² can be received. Sound intensity refers to the amplitude of the sound and is expressed in decibels (dB SPL - Sound Pressure Level).

When the noise increases with a call, it means 10 times the intensity is made. The human ear is capable of much smaller differences can be observed (between 0.2 and 0.3 Bel). Therefore, the decibel introduced. The decibel scale is the horn divided into 120 steps.

The figure below shows some noise of some everyday sounds appear.

 

 

Our ear is most sensitive to sounds in the frequency range between 500 and 8000 Hz. Tones below and above are required to have a greater amplitude observed to be equally loud.

 

The red and blue tone have the same frequency.
The red tone is louder than the blue.

 

The maximum deflection known as the amplitude is larger than the red tone in the blue tone. The frequency is the same. The surrounding air particles get through the red show more energy than the blue tone. The red tone will be perceived as louder than the blue tone. Hard, soft, loud, weak are all subjective descriptions of the physical understanding, volume.