Question

Which characteristics of the sound help you to identify your friend by his voice while sitting with others in a dark room?

Answer 1

Hint: The question talks about sound waves and its characteristics such as amplitude, wavelength, frequency, timbre and pitch. They are basic features that must be looked forward to if sound must be produced.

Complete step by step answer:
Sound waves are longitudinal waves. They have amplitude, wavelength, frequency, timbre, pitch etc.
The identification of a friend’s voice can be attached to the pitch and timbre of the sound waves produced around the person. Timbre is also called quality. It is what makes a particular sound have a different effect on our ear from the other sounds. Sounds can have the same pitch but timbre is different for every sound produced.
Air molecules always surround a person and immediately energy in the form of force contacts these air molecules.
Waves or disturbances are triggered by the molecules, the molecules of air are then said to be in motion at that point where there is push from the mouth to the air molecules (sound waves).
Also sound waves travel fast in the dark at night because the molecules of the wave medium are at rest and they have no considerable amount of kinetic energy for actions along the path of the medium or media with some or the entire portion of the medium particles.
Kinetic theory of gases also explain the behavior of gas (air) molecules that are moving within a certain and confined area, immediately when a force is applied gas molecules tend to compress or expand.

Note: Such can be observed also in two different musical instruments where we can tell if one is a guitar and the other a piano without going close to the scene of play and also between a talking drum and a cymbal their level of outputs differ.