The loudness of sound is a measure of the sound energy reaching the ear per second.
The loudness of sound is measured in ‘decibel’. It is written as dB.
Pitch is that characteristics of sound by which we can distinguish between different sound of the same loudness.
The pitch of a sound depends on the frequency of vibration.
The pitch of a sound is directly proportional to its frequency.
Higher the frequency of sound, higher is the pitch.
QUALITY (OR TIMBRE)
Quality (or timbre) is that characteristic of musical sound which enables us to distinguish between the sounds of same pitch and loudness produced by different musical instruments (and different singers).
The quality (or timbre) of a musical sound depends on the shape of sound wave (or waveform) produced by it.
INTENSITY OF SOUND
The amount of sound energy passing each second through a unit area is called the intensity of the wave.