VOLUME, PITCH AND TIMBRE OF SOUNDS

Sounds are characterised by their own volume, pitch and timbre. More generally, sounds are also characterised by their length, corresponding to their duration.
The 'volume' of a sound is its 'intensity', called acoustic intensity or loudness.
From a physical point of view, the volume of a sound can be defined as the ratio between the power of a sound wave and the area of the surface it passes through. In other words, one can consider the volume of a sound as the energy that perpendicularly crosses a surface in a certain time.
Therefore, the volume of a sound, in the International System of Units, can be expressed as watts per square metre.
Humans are able to perceive sounds with a volume within a range of approximately 12 orders of magnitude, from sounds on the threshold of audibility (approximately 10^-12 W/m^2) to those on the threshold of pain (approximately 1 W/m^2). Below the threshold of hearing no sound is perceived, while above the threshold of pain sounds are painful to the ear.
Because of this wide range, loudness is usually expressed on a logarithmic scale and is measured in decibels.
Pitch' refers to the pitch of a sound and depends on the frequency of the vibrations that give rise to the sound. Such vibrations can be generated, for example, by the strings of a guitar or even vocal chords.
Usually, human beings are able to perceive sounds characterised by a number of vibrations between 20 and 20000 per second, i.e. between 20 and 20000 hertz.
The lower the number of vibrations in the unit of time, the lower the sound will be. Conversely, the higher the number of vibrations in the unit of time, the higher the sound will be.
The lowest sounds generated by the human voice are characterised by approximately 90 vibrations per second, while the highest sounds are characterised by approximately 1500 vibrations per second.
The musical note that gives the pitch its name is called the 'tonic'. The other 6 musical notes are called, in order, 'sopratonic', 'modal', 'subdominant', 'dominant', 'supra-dominant' and 'sensitive'.
A distinction is also made between a 'major' and a 'minor' mode. Parallel tones" are those that have the same tonic. Relative tonalities' are those that have the same armature, i.e. the same alterations.
While the volume, pitch and length of a sound are physical quantities that can be measured using phonometers, frequency meters and stopwatches respectively, the same cannot be said of the 'timbre' of a sound, which characterises the sound in and of itself and is different from individual to individual, from musical instrument to musical instrument.
In other words, the timbre of a sound can be considered as that quality of sound that makes it possible to distinguish between two sounds with equal frequency. Suffice it to think, in fact, of the timbre of the voice, which identifies each person like a sort of fingerprint.