ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: NE2000 on June 27, 2009, 03:43:53 pm
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My book talks about there generally being multiple harmonics present in a string or wind instrument due to multiple standing waves being produced, each of which have the same speed (but obviously a different frequency as they are different harmonics). In other words, the fundamental frequency and the multiple resonance frequencies exist simultaneously in the instrument. I'm a bit confused as to how this is possible, mainly because I thought the idea was that the principal vibrator will produce the sound wave and that the standing wave produced will be the result of the reflection of that sound wave. But I don't see how that would produce multiple standing waves. Could someone please explain?
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Hmm I thought about it and is it because when someone plays into the instrument they create multiple sound waves and each of them will reflect. So you get different harmonics existing due to the different frequency of the sounds they create? In that case, each of the harmonics will resonate within the instrument for a certain amount of time until it loses its energy. Is that on the right track?
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My book talks about there generally being multiple harmonics present in a string or wind instrument due to multiple standing waves being produced, each of which have the same speed (but obviously a different frequency as they are different harmonics). In other words, the fundamental frequency and the multiple resonance frequencies exist simultaneously in the instrument. I'm a bit confused as to how this is possible, mainly because I thought the idea was that the principal vibrator will produce the sound wave and that the standing wave produced will be the result of the reflection of that sound wave. But I don't see how that would produce multiple standing waves. Could someone please explain?
The fundamental frequency and multiple resonance frequencies will exist because of different instruments resonators. For example, in a piano you hit the key which hits the string and it produces a range of standing waves depending on how hard you made the string vibrate. This vibration is then transferred from the string to the resonator, in the case of a piano it would be the "body" of the piano, hence the vibrations can be modified producing different harmonics. When another string is hit this will also be transferred to the resonator which produces another harmonic. Hence different harmonics can exist at the same time.
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My book talks about there generally being multiple harmonics present in a string or wind instrument due to multiple standing waves being produced, each of which have the same speed (but obviously a different frequency as they are different harmonics). In other words, the fundamental frequency and the multiple resonance frequencies exist simultaneously in the instrument. I'm a bit confused as to how this is possible, mainly because I thought the idea was that the principal vibrator will produce the sound wave and that the standing wave produced will be the result of the reflection of that sound wave. But I don't see how that would produce multiple standing waves. Could someone please explain?
The fundamental frequency and multiple resonance frequencies will exist because of different instruments resonators. For example, in a piano you hit the key which hits the string and it produces a range of standing waves depending on how hard you made the string vibrate. This viration is then transferred from the string to the resonator, in the case of a piano it would be the "body" of the piano, hence the vibrations can be modified producing different harmonics. When another string is hit this will also be transferred to the resonator which produces another harmonic. Hence different harmonics can exist at the same time.
So it's just the action of the principal vibrator? As in the principal vibrator can create different standing waves depending on a range of factors and they coexist?
The bit that confused me was the suggestion that typically all of the first five standing waves exist at once. Say you press one key on the piano and then left it. Would there be multiple standing waves?
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Yes the principle vibrator (in the case of the piano would be the string), it creates the standing wave (this standing wave does not necessarily have to be the fundamental frequency it could be any resonant frequencies). And ofcourse when you strike different keys different resonant frequencies will form [as a result different harmonics will form], the resonator (the body of the the piano) "contains" these different harmonics.
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My book talks about there generally being multiple harmonics present in a string or wind instrument due to multiple standing waves being produced, each of which have the same speed (but obviously a different frequency as they are different harmonics). In other words, the fundamental frequency and the multiple resonance frequencies exist simultaneously in the instrument. I'm a bit confused as to how this is possible, mainly because I thought the idea was that the principal vibrator will produce the sound wave and that the standing wave produced will be the result of the reflection of that sound wave. But I don't see how that would produce multiple standing waves. Could someone please explain?
The fundamental frequency and multiple resonance frequencies will exist because of different instruments resonators. For example, in a piano you hit the key which hits the string and it produces a range of standing waves depending on how hard you made the string vibrate. This viration is then transferred from the string to the resonator, in the case of a piano it would be the "body" of the piano, hence the vibrations can be modified producing different harmonics. When another string is hit this will also be transferred to the resonator which produces another harmonic. Hence different harmonics can exist at the same time.
So it's just the action of the principal vibrator? As in the principal vibrator can create different standing waves depending on a range of factors and they coexist?
The bit that confused me was the suggestion that typically all of the first five standing waves exist at once. Say you press one key on the piano and then left it. Would there be multiple standing waves?
No, if you pressed one key, you would only get one resonant frequency, if you pressed 2 keys, you'd get 2 resonant frequencies and so on.
Hence that's how harmonies are formed in piano, playing a 'triad' which consists 3 notes with the same difference in interval between them creates harmonics. [because each note has a frequency which is a multiple of the fundamental frequency]
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My book talks about there generally being multiple harmonics present in a string or wind instrument due to multiple standing waves being produced, each of which have the same speed (but obviously a different frequency as they are different harmonics). In other words, the fundamental frequency and the multiple resonance frequencies exist simultaneously in the instrument. I'm a bit confused as to how this is possible, mainly because I thought the idea was that the principal vibrator will produce the sound wave and that the standing wave produced will be the result of the reflection of that sound wave. But I don't see how that would produce multiple standing waves. Could someone please explain?
The fundamental frequency and multiple resonance frequencies will exist because of different instruments resonators. For example, in a piano you hit the key which hits the string and it produces a range of standing waves depending on how hard you made the string vibrate. This viration is then transferred from the string to the resonator, in the case of a piano it would be the "body" of the piano, hence the vibrations can be modified producing different harmonics. When another string is hit this will also be transferred to the resonator which produces another harmonic. Hence different harmonics can exist at the same time.
So it's just the action of the principal vibrator? As in the principal vibrator can create different standing waves depending on a range of factors and they coexist?
The bit that confused me was the suggestion that typically all of the first five standing waves exist at once. Say you press one key on the piano and then left it. Would there be multiple standing waves?
No, if you pressed one key, you would only get one resonant frequency, if you pressed 2 keys, you'd get 2 resonant frequencies and so on.
Hence that's how harmonies are formed in piano, playing a 'triad' which consists 3 notes with the same difference in interval between them creates harmonics. [because each note has a frequency which is a multiple of the fundamental frequency]
ok, that's what I originally had always thought but the book confused me, thanks for clearing that up :)
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Is this just the 'beat'-ing effect of superposition?
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Is this just the 'beat'-ing effect of superposition?
no.