10.1: Elements of Sound

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Christopher Clemens
Laney College, City College of San Francisco, San Francisco State University, Los Angeles City College via ASCCC Open Educational Resources Initiative (OERI)

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Sound Waves

Amplitude

Sound travels through the air in waves. The components of those waves dictate the volume and pitch of that sound. For instance, the Amplitude of the wave (how tall the wave is as demonstrated in figure 10.1.1) dictates the volume of the sound. We measure the amplitude of sound in decibels (dB). The threshold of hearing starts at 0dB, the threshold of pain starts around 120dB, and the instant perforation of the human eardrum is around 160dB.

Frequency

Another important element of sound is Frequency which dictates the pitch of the sound. Frequency refers to how many full-wave cycles happen per second (See figure 10.1.1), which is measured in hertz (Hz). The typical male voice frequency is between 85 to 100 Hz. The typical female voice frequency is between 165 to 255 Hz. When listening to music, you may be able to adjust the bass (20-200 Hz), midrange (200-2000 Hz), or treble (2-18 kHz) on your music player.

Sound vs. Audio

Sound and audio are commonly used interchangeably, but they actually refer to two different things. Sound is vibration waves moving through materials, like air, walls, and water. When we speak, our vocal cords vibrate from air flowing between them, which creates a sound that comes out of our mouths. In other terms, it is the mechanical creation of sound waves.

Audio is an electrical representation of sound. When a microphone picks up sound, it turns sound waves into electric sound signals that get recorded. The electric sound signal is audio. It can be converted, manipulated, edited, and played back. When you play the audio back, a speaker then translates the audio signal into sound waves that we can hear (See figure 10.1.2).

This flow chart is described in the figure caption. — Figure \(\PageIndex{2}\): Diagram of sound being converted from sound waves into audio signals with a microphone, converted into digital information in a computer, converted into audio signals, and back into sound waves through a speaker. (CC BY-SA 3.0; Teeks99 via Wikimedia Commons)