Question

How is it possible to recognize a person by his voice without seeing him?

Answer 1

While talking on a phone, one does recognize the voice of a person and can identify that person without seeing the person in reality. This is because the human brain is familiar with the frequency and amplitude of the sound and can immediately make a guess of the voice of that person.

Complete step by step answer:
In having a conversation with anyone, the brain is more attentive towards the eyes and the voice of that person. The brain actually stores the memory of the voice with the help of frequency, pitch, amplitude of the voice. One can also identify the person by the accent of his language, as accents may differ for different languages and also with the softness and harshness of the voice.
Sound or voice travels in the forms of waves just as light and the electromagnetic waves. Sound waves have the properties of frequency, pitch and amplitude.
Frequency is the number of vibrations in the waves that are travelling in a particular interval of time, mostly one second. Pitch of sound differentiates between relatively high and low frequencies of the sound wave vibrations. High pitch is the case when the frequency increases suddenly for some time. Amplitude is associated with the number of molecules corresponding to the sound wave.

Note:
If a person speaks on a mike, then the frequency, pitch and amplitude can change in some aspects. The sound delivered by the mike may not be the same as one’s original speech. The change in the sound depends on mike settings. Change of voice may also occur if one produces an echo. The echo sound is heard two to three times and with different frequency everytime.