The larynx is a complex system of muscle and cartilage that supports and moves the vocal cords, or, as they’re more accurately known, the vocal folds. Strung between the thyroid and arytenoid cartilages, these two muscles form an elastic curtain that opens and shuts across the trachea, the tube that carries air through the throat. The folds are apart when we’re breathing, but when we speak, they slam shut. Our lungs push air against the closed folds, blowing them open and vibrating the tissue to produce sound. Unlike the deliberate focus required for playing an external instrument, we effortlessly change notes as we speak. By pushing air faster or slower, we change the frequency and amplitude of these vibrations, which respectively translate to the pitch and volume of our voices. Rapid and small vibrations create high-pitched, quiet tones, while slow, large vibrations produce deep, bellowing rumbles. Finally, by moving the laryngeal muscles between the cartilages, we can stretch and contract those folds - to intuitively play our internal instruments.