You hear sounds all day long. Some sounds you probably enjoy (you and your friends laughing - yay!), while others you may not (garbage trucks on trash day - ugh). Have you ever stopped to think about what sound actually is though?
Sound is a type of energy made by vibrations. When objects vibrate, they cause movements in the air particles. These particles vibrate as well and bump into other particles close to them. The reaction of all this movement caused by particles bumping into each other is called sound waves and sound waves just keep going until the particles run out of energy. If your ear is within range of the vibrations, you hear the sound. Picture throwing a penny into a bathtub. The rings of waves expand until they reach the end of the bathtub. The same is true with sound.
Two of the most frequent sounds we hear as humans are speech and music. In speech and music, sound is broken up into a combination of frequencies andfrequencies can be measured by something called the Fourier transform, which is named after French mathematician Joseph Fourier. He came up with a measurement to breakdown frequencies into something we call pitch. Pitch is the part of frequency that us humans can hear and is probably something you’ve heard of before in reference to speech or music.
Music generally carries less complicated pitches than speech. In wind instruments, like the flute and trumpet, vibrating air makes the sound. The particles move back and forth creating sound waves. Different pitches are played by pressing keys that open or close holes in the tube making the air column inside the tube longer or shorter. Longer air columns produce lower pitches. Stringed instruments are played by pressing the fingers down on the strings. The pressure of pressing changes the strings' length, causing them to vibrate at different frequencies and making different sounds. Pitch is determined by length and thickness of strings.
Speech is more complicated when it comes to pitch, because there’s more vibration variance in a single pitch.Speech pitch varies a lot depending on the height of the speaker. Women and children tend to have higher pitches voices because they are generally shorter and men tend to have higher pitched voices because they are generally taller. In US culture, we often convey seriousness and sometimes mischief with lower pitches voices and friendliness and innocence with higher pitched voices. Can you think of examples of notable high and low pitched voices?
Speech pitch is also complex when it comes to language. Language meaning can vary a lot depending on the pitch of a voice. One example of this is how pitch creates different meanings in English sentences and phrases. A rising pitch at the end of the phrase means something different than a falling pitch. “The dog?” indicates a question but a falling pitch, as in, “The dog.” indicates more of an answer. In Mandarin Chinese, where the changing pitch of a speaker actually helps determine the meaning of a singular word, there are 4 defined pitches that completely change word meaning depending on the pitch they are said in. If you say the word ma the way an English speaker would say it, just reading it from a page, then it means “scold.” If you were to say ma as if you were looking for your mother—ma?— it means “rough.”
Despite that we have a certain range of pitches we stay in when talking, there are ways to change the pitch of your voice outside of its normal range. This is done a lot on TV, radio and in movies, specifically with cartoon characters. The most common way to alter your voice is called pitch shifting. Pitch shifting is a sound recording technique using math in which the original pitch of a voice is raised or lowered. It’s done using measured electronic devices and can alter the pitch of voices so much, that they aren’t even recognizable by their owners! One of the best examples of pitch shifting is in the voice of Mickey Mouse. Walt Disney himself actually played his voice at one point, and, now the Mickey Mouse voice legacy carries on as a result of pitch shifting.
Are you curious what your cartoon voice would sound like, high or low?Audacity is an open-sourceaudio editor that can help you with the basics of pitch shifting your voice.
Have fun and remember, sound, vibrations and pitch can all be explained by math!
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