Why Does Helium Gas Affect Sound?

Helium is the most abundant element in the universe after hydrogen. It is also the second element, which is the lowest in terms of molecular mass. To understand why the sound of someone absorbing helium gas changes, it is necessary to understand the sound waves. Helium gas changes the timbre of the sound. The sound being thin and thick is related to the timbre of the sound.

First of all, let’s talk about how sound is formed. In terms of physiological vision, the sound is the sense of hearing, consisting of rhythmic and regular vibrations of the vocal cords. The human voice is a complex mechanism resulting from the coordinated work of many organs. Some of the structures involved in sound formation are:

• Lungs
• Larynx
• Farynx 
• Nose
• Mouth
• Trachea 

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Sound travels in different environments, such as creating pressure waves in the air. As sound waves propagate in the air, they cause minor changes in the pressure of the air. While pressure is high in regions where air molecules are concentrated, the pressure is low in areas where it is rare. However, sound waves move at different speeds in different environments.

For example, at 20° C, the speed in the air is 344 meters per second (about 1240 kilometers/hour), while the speed in helium gas at the same temperature is 927 meters per second (about 3340 kilometers/hour). So when we breathe helium gas, our voice spreads faster than in the air. However, this does not mean that the frequency of the waves has changed.

Frequency can be defined as the number of sound waves emitted in a given time period and is usually expressed in the number of vibrations per second, or Hertz. As the air coming from our lungs passes through the larynx, the vibrating vocal cords provide our voice. The number of times that the vocal cords vibrate per second determines the frequency of the sound, and the frequency determines whether the sound is high or thick. The reason for the change in our voice when we breathe helium gas is the different perception of the sound waves moving faster.