Humming is a harmonious sound created by the vibration of the vocal cords as air is expelled from the lungs. Interestingly, trying to hum with your nose held shut proves to be a compelling demonstration of how the human body manages airflow during vocalization. When you hum, air moves from the lungs through the vocal cords and out of your body primarily through your nose because your mouth is closed. This flow of air is essential for the creation of the humming sound.
Holding your nose while trying to hum blocks this necessary exit route for the air, leading to a quick halt in the humming sound. Essentially, the closed nasal passages prevent air from escaping, and without a flow of air, the vocal cords cannot continue to vibrate in a way that produces sound. You might manage to produce a brief humming noise due to any initial air pressure built up in the oral and nasal cavities, but this will be short-lived, and the sound will cease once all the air is expended or if you have to breathe again.
This little experiment is a delightful insight into the mechanisms of singing and speech and highlights the important role of the nose in vocalization. Not only is the nose a pathway for airflow, but it is also crucial in creating resonance, which enriches the quality of the voice. Thus, the inability to hum with both mouth shut and nose held highlights an intriguing intersection of physiology and the physics of sound, providing more than just a party trick but also a useful lesson in human biology and the science of sound.
