Which characteristic of sound, makes it possible to recognize a person by his voice without seeing him ?

Explanation

To answer the question, "Which characteristic of sound makes it possible to recognize a person by his voice without seeing him?", we can break down the solution into the following steps:

### Step 1: Understand the Characteristics of Sound
Sound has several characteristics, including pitch, loudness, and timbre. Each of these plays a role in how we perceive sound.

### Step 2: Define Pitch
Pitch refers to how high or low a sound is. It is determined by the frequency of the sound waves. Different people have different pitches in their voices.

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