The Physics of Sound Waves in Musical Instruments

In summary, the sound produced by a musical instrument is a combination of a single wave, known as the ground frequency, and its harmonics (n*f_n). The ground frequency determines the pitch of the sound, while the harmonics add complexity and can make the sound seem "noisy". Harmonics are related to wave coherence, as they are part of the harmonic wave packet, and are also connected to concepts such as resonance and coherence in physics.
  • #1
sci-guy
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Is the sound of one note generated by a musical instrument an example of a single sound wave or a group of in-phase (coherent) sound waves?
 
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  • #2
In practice, just about all sounds are actually wave packets (a group) with harmonics etc.
But the ideal of a single note is a single wave.
 
  • #3
In short, the sound you hear from a musical instrument is composed of it's ground frequency (f_n), this being the frequency with the largest amplitude, which defines the pitch that you hear, and all of it's harmonics (n*f_n) where n is a whole positive number.

For example, if you pick the E string of a guitar, you will hear an E tone in the second octave (82.41 Hz) Because this is the ground frequency and thus the frequency with the largest amplitude. The harmonics are also present, but they are all of a smaller amplitude and do not alter the pitch of the tone since their amplitudes are smaller (decreasing as n increases i think). The harmonics do however make the note seem more "unclean" or "noisy" than if it was only the E tone present, without the harmonics. I do think however that some instruments play their notes with more or less "harmonics pollution".
 
  • #4
Do harmonics relate to wave coherence? In other words, are the sound waves in this "harmonic wave packet" said to be coherent in physics?
 
  • #5
Harmonics, resonance, coherence -- are these related?
 

1. How do sound waves produce music in different instruments?

Sound waves are produced when a source, such as a musical instrument, creates vibrations that travel through a medium, such as air. In musical instruments, these vibrations are created by plucking, striking, or blowing into the instrument, which causes the air molecules to vibrate and produce sound waves. The unique shape and materials of each instrument determine the specific properties of the sound waves produced, resulting in different musical notes and timbres.

2. What is the role of frequency and wavelength in musical sound waves?

Frequency and wavelength are two important properties of sound waves that determine the pitch and tone of musical notes. Frequency refers to the number of vibrations per second and is measured in Hertz (Hz). The higher the frequency, the higher the pitch of the sound. Wavelength, on the other hand, is the distance between two consecutive peaks or troughs of a sound wave and is inversely proportional to frequency. This means that shorter wavelengths correspond to higher frequencies and vice versa.

3. How do musical instruments amplify sound waves?

Instruments such as guitars and pianos have hollow bodies or sound boxes that act as resonators, amplifying the sound waves produced by the instrument. This is achieved through the principle of resonance, where the air inside the instrument vibrates at the same frequency as the sound waves produced, resulting in a louder sound. Other instruments, such as brass and woodwind instruments, use vibrating columns of air to amplify the sound waves and produce different notes.

4. What is the difference between acoustic and electric musical instruments in terms of sound waves?

The main difference between acoustic and electric instruments is the way in which sound waves are produced and amplified. Acoustic instruments rely on the natural vibrations of air molecules to produce sound, while electric instruments use electronic amplification to produce and amplify sound waves. This allows for greater control and manipulation of the sound, resulting in a wider range of musical effects and styles.

5. How do sound waves travel and interact in an ensemble or orchestra?

In an ensemble or orchestra, sound waves from different instruments interact and combine to create a cohesive musical performance. This is achieved through a process called interference, where sound waves with similar frequencies and wavelengths either reinforce or cancel each other out. The placement and arrangement of instruments also play a role in how sound waves interact, with some instruments acting as sources while others act as resonators or amplifiers.

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