Why does the pitch of my voice rise after inhaling helium

A.� Because the pitch that your larynx, or voice box, produces is dependent on either its size or the speed that sound passes over your vocal cords. So you can change the pitch of your voice either by increasing the size of your larynx or by allowing sound to travel faster from one side of it to the other.

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In the case of inhaling helium you're doing the latter. Sound travels much faster through helium than air, almost three times as fast, temporarily giving you a very squeaky voice due to its higher pitch. As soon as the helium is out of your lungs your voice returns to normal.

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Q.� So, why do men normally have deeper voices than women

A.� In this case the size of the larynx lowers the pitch of the voice. Men have larger larynxes than women, giving them a deeper pitched voice.

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Q.� How does the larynx aid speech

A.� The larynx, or voice box, plays a crucial role in producing sound for speech. Two vocal cords lie in the centre of our larynx. As we speak the two cords are brought close together by a set of muscles. Air being expelled from the lungs passes over the cords, causing them to vibrate, producing a sound.

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This sound is then modified by our throat tongue and lips, producing speech.

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Q.� Since we're the only animals that speak, is our larynx unique

A.� A newborn baby's larynx is similar to that of other mammals, but at around 3 months it descends, opening up a cavity behind the tongue. This change allows us to make a wider range of sounds essential for the evolution of speech.

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In adolescent boys the larynx drops a second time when the voice breaks, deepening the voice.

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Do you want to know how a part your body works Click here to ask.

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by Lisa Cardy