Many of us have had the experience of sucking helium from a balloon or witnessing someone else perform this act. We know that when this happens it changes the sound of our voice to produce a high, squeaky, chipmunk type sound. This effect is only temporary and lasts for a few seconds and then more helium must be breathed in to produce the effect again. Why does helium change our voice to produce high pitched sounds? Read this article to find out.
How Do We Make Different Sounds?
To understand why helium changes our voices, we first must understand how we produce sound to begin with. Each of us has a set of vocal chords inside our throats. Sound is made by pushing air from our lungs through our vocal chords in the throat. These cords open and close hundreds of times a second producing a series of little puffs of air which end up in your mouth. The momentum of the air carries it out of your mouth. This causes the air pressure in your mouth to be lower than that outside of the mouth. This means that the air will then be sucked back in. When you are making sound your vocal chords make a number of different frequencies. The one that is heard the most is the one that is the same as the resonant frequency made by the air entering and leaving your mouth. The resonant frequency depends on the shape of your mouth.
How Does Helium Change The Sound Of Your Voice?
So how does breathing helium change our voice? Well, when you breathe helium it changes the momentum of the air in and out of your mouth. Helium is much lighter than air making it move much faster. The inhalation of helium increases the resonant frequency of your mouth meaning that the higher frequency sounds will be amplified more than they would in normal air. This means that people listening to your will more clearly hear the higher frequencies produced by your vocal cords making you sound squeaky. The lower frequencies are still there, but are quieter and more difficult to discern over the amplified higher frequencies.
The following video provides an easy to understand explanation of this process: