The Perceptual System

Our perceptual experience is motivated by the displacement of the gas molecules that appear in the air. If there is no air, there is no sound. When an object starts to vibrate, this movement causes the displacement, these gas molecules run into each other and produce soundwaves.

The physical properties of these soundwaves are:
- Frequency
- Amplitude
- Phase angle

Of the three, frequency is the characteristic which mostly influence in our perception of a sound. That is, our auditory system is especially sensitive to changes in frequencies.

However, other important factors are:
- duration
- amplitude
- previous sounds
- our attention at the moment the sound is produced

Let´s now speak about 3 important features related to sound perception:
1) Amplitude (Volume): The wider the amplitude of the soundwave, the louder the perception we receive. However, there is not a one-to-one correlation between amplitude (volume) and perception: background noise, the listener's characteristics and frequency can influence on a better or worse reception of sounds

2) Simultaneous sounds: When two sounds are combined, the resulting sound depends on the difference in the frequency of the two sounds.