Basic Physics of Music
What is Sound?
Sound is made up of waves, which are created from vibrations. These vibrations interact with the air around them and travel, eventually interacting with our ears to create sound as we know it. Sound can be measured using the wavelength, amplitude, and frequency of the sound waves. Wavelength is the measurement between the same two points between two adjacent waves. The wavelength of a sound wave as well as the speed can be used to determine the frequency which describes the number of wavelengths measured over one second, and is measured in Hertz (Hz). Frequency is used to describe how high or low the note produced sounds, and is also called pitch. For instance the frequency of the the common tuning standard note A is 440 Hz. The note A has many frequencies depending on the octave of the note. Octaves are used to describe a music note and another that corresponds to a note with half the frequency (1). These notes will be referred to as the same letter. Amplitude is the height of the wave, and describes how loud the sound wave is. If the amplitude is higher the sound is louder, and if the amplitude is lower the sound is quieter (2).
Another measurement of sound waves are compression and rarefaction, which describe the pressure of the waves. Compression describes higher pressure areas and rarefaction describes lower pressure areas (2).
The pictures below show sound waves. The picture to the left shows wavelength, amplitude, rarefaction and compression. The picture to the right shows waves of different frequencies (from top to bottom: lower frequency to higher frequency).
Another measurement of sound waves are compression and rarefaction, which describe the pressure of the waves. Compression describes higher pressure areas and rarefaction describes lower pressure areas (2).
The pictures below show sound waves. The picture to the left shows wavelength, amplitude, rarefaction and compression. The picture to the right shows waves of different frequencies (from top to bottom: lower frequency to higher frequency).
How Does this Relate to Music?
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Music is a type of sound that people often use to express and share emotions. Musical instruments are key in producing a variety of sounds in order to accomplish this, and can create sounds that people can't on their own. Musical instruments are made in order to create vibrations that cause the specific sounds that we hear. Instruments are also tuned in order to make sure that the frequency of the sound is what is expected, and many instruments use various mechanisms so the person playing it can change frequency (and play different music notes) in order to play a tune. When playing instruments, people can change the volume that the instrument is playing, changing the amplitude of the sound waves.