Sounds Of Music C

mjcox2000
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Re: Sounds Of Music C

Post by mjcox2000 » April 1st, 2019, 4:13 am

wec01 wrote:
mjcox2000 wrote:
wec01 wrote:
The key could be touching a support and vibrating against it or the chord going through the keys could be too lose (although I think that would affect other keys as well so it's more likely the first issue).
Having the bar touch a support could certainly be the reason it’s buzzing. (Usually this would be because a rubber spacer on the support fell off). On the other hand, the cord being too small won’t cause it to buzz, since the cord is soft and has plenty of give to it.
Anna checks her marimba for the things you mentioned and discovers that they’re not the problem. What should she check next?
an issue with the resonators, so she could check to see if the buzzing is still heard when the resonator is blocked.
If it’s a screw rattling on the resonators, it will likely rattle for multiple notes, not just the one. But if it’s a loose resonator cap or an object inside the resonator, it should rattle for just the one note.
There’s one more main thing the issue could be — what is it?
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UTF-8 U+6211 U+662F
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Re: Sounds Of Music C

Post by UTF-8 U+6211 U+662F » April 15th, 2019, 5:23 pm

mjcox2000 wrote:
wec01 wrote:
mjcox2000 wrote:
Having the bar touch a support could certainly be the reason it’s buzzing. (Usually this would be because a rubber spacer on the support fell off). On the other hand, the cord being too small won’t cause it to buzz, since the cord is soft and has plenty of give to it.
Anna checks her marimba for the things you mentioned and discovers that they’re not the problem. What should she check next?
an issue with the resonators, so she could check to see if the buzzing is still heard when the resonator is blocked.
If it’s a screw rattling on the resonators, it will likely rattle for multiple notes, not just the one. But if it’s a loose resonator cap or an object inside the resonator, it should rattle for just the one note.
There’s one more main thing the issue could be — what is it?
an issue with the mallets?

mjcox2000
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Re: Sounds Of Music C

Post by mjcox2000 » April 16th, 2019, 3:05 am

UTF-8 U+6211 U+662F wrote:
mjcox2000 wrote:
wec01 wrote:
an issue with the resonators, so she could check to see if the buzzing is still heard when the resonator is blocked.
If it’s a screw rattling on the resonators, it will likely rattle for multiple notes, not just the one. But if it’s a loose resonator cap or an object inside the resonator, it should rattle for just the one note.
There’s one more main thing the issue could be — what is it?
an issue with the mallets?
An issue with the mallets would cause buzzing on every note, not just the one note.
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ThomasL
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Re: Sounds Of Music C

Post by ThomasL » May 9th, 2019, 3:45 pm

There is a minor horizontal crack in the bar since the bar primarily vibrates by flexing lengthwise.

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Re: Sounds Of Music C

Post by mjcox2000 » May 9th, 2019, 4:48 pm

ThomasL wrote:
There is a minor horizontal crack in the bar since the bar primarily vibrates by flexing lengthwise.
That’s right! Your turn.
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Re: Sounds Of Music C

Post by smayya337 » May 23rd, 2019, 2:43 pm

A new concert hall has opened near my house. It's a closed rectangular box 50 meters long, 50 meters wide, and 20 meters high. What are the three fundamental frequencies of this hall?
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Re: Sounds Of Music C

Post by SciolyMaster » May 23rd, 2019, 3:19 pm

smayya337 wrote:A new concert hall has opened near my house. It's a closed rectangular box 50 meters long, 50 meters wide, and 20 meters high. What are the three fundamental frequencies of this hall?
1.7 Hz, 1.7 Hz, 4.3 Hz
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smayya337
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Re: Sounds Of Music C

Post by smayya337 » May 23rd, 2019, 3:33 pm

SciolyMaster wrote:
smayya337 wrote:A new concert hall has opened near my house. It's a closed rectangular box 50 meters long, 50 meters wide, and 20 meters high. What are the three fundamental frequencies of this hall?
1.7 Hz, 1.7 Hz, 4.3 Hz
Close, but not quite! Your numbers were all off by the same factor - you might want to check your math again.
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Re: Sounds Of Music C

Post by SciolyMaster » May 23rd, 2019, 3:53 pm

smayya337 wrote:
SciolyMaster wrote:
smayya337 wrote:A new concert hall has opened near my house. It's a closed rectangular box 50 meters long, 50 meters wide, and 20 meters high. What are the three fundamental frequencies of this hall?
1.7 Hz, 1.7 Hz, 4.3 Hz
Close, but not quite! Your numbers were all off by the same factor - you might want to check your math again.
Isn't it a closed air column though? The wavelength should be 4x the length of the room,
[math]343/(4*50)=1.7[/math]for the two 50 m sides and [math]343/(4*20)=4.3[/math]for the 20 m side.
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smayya337
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Re: Sounds Of Music C

Post by smayya337 » June 1st, 2019, 6:28 am

SciolyMaster wrote:
smayya337 wrote:
SciolyMaster wrote:
1.7 Hz, 1.7 Hz, 4.3 Hz
Close, but not quite! Your numbers were all off by the same factor - you might want to check your math again.
Isn't it a closed air column though? The wavelength should be 4x the length of the room,
[math]343/(4*50)=1.7[/math]for the two 50 m sides and [math]343/(4*20)=4.3[/math]for the 20 m side.
From what I understand, the formula for a closed rectangular box's resonant frequencies should be [math]\frac{v}{2} = \sqrt{(\frac{l}{L_x})^2+(\frac{m}{L_y})^2+(\frac{n}{L_z})^2}[/math], and with [math]L_x = 50, L_y = 50[/math], and [math]L_z = 20[/math], you can substitute 0, 0, and 1 in any order as [math]l, m,[/math] and [math]n[/math] to get [b]3.4 Hz and 8.6 Hz[/b].

The simpler way, of course, would also be to just find [math]343/(2*50)[/math] and [math]343/(2*20)[/math]

I think you got a fully closed air column confused with a stopped air column, which is closed on one side but not the other. To the best of my knowledge, a fully closed air column should have a fundamental wavelength 2x the length of the room, similar to a string.
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