The larynx, also known as the voice, is a 2-inch (1 inch = 2.54 cm) long tube-like organ located in the neck that we use to breathe, make sounds and assist in swallowing. The larynx is at the top of the trachea and its circumferential wall is made up of cartilage, the largest of which is called the laryngeal node, which forms the anterior part of the larynx. Two bar-shaped muscles in the larynx form the vocal cords. Every moment, when we inhale air, it passes through the nasal or oral cavity, then through the laryngeal cavity and into the trachea to the lungs; when we exhale, it flows out in the opposite direction. When we breathe, the vocal cords on both sides are relaxed and air passes between them without the vocal cords making any sound. The role of the larynx during respiration is to change the size of the airway to fit the needs of the body. The larynx also has an auxiliary role in the ventilation of the alveoli and in maintaining the acid-base balance of body fluids. When we speak, the vocal cords are tensed and closed bilaterally, and the gas exhaled from both lungs passes through the vocal cords, causing them to vibrate and produce sound. The contraction of the intralaryngeal muscle moves the laryngeal cartilage and changes the position of the cartilages in relation to each other to close and open the vocal folds. The contraction of the intralaryngeal muscle also changes the mass, length and tension of the vocal folds. The extralaryngeal muscles are also involved in vocalization. Normal vocalization is a highly complex process in which the larynx is controlled by the random and reflex systems. It involves three processes: pre-vocal modulation of vocal tone, vocal reflex modulation, and voice monitoring, any one of which can cause vocal abnormalities if impaired. The tongue, lips and teeth convert sound into speech.