Headbasket design

[kooma]

theoretically everything above 68KHz goes straight thru, but all audible frequencies will have some sort of effect?

Everything under  68 kHz goes more or less straight thru.

If we are talking about hole with size of 5mm then everything and above(shorter) waveform of 5mm(68KHz) goes pass it,
and everything under it(longer waveform)  has some sort of "bending/reflection" or have I missed/misunderstood something?

Thanks for the links!

 

[tubestation]

Hello,
Everything shorter than the Barrier get s reflected.  It s not a Matter of the Holesize but the solid Space between the Holes where the shorter Wave get s reflected. But this is only a  more or less theoretical , imperical Analysis, in Reality Things are different. All Modells of Acustic Theory have there  Problems to explain everything, so all are wrong  from a Science View. Larger Wavelenght pass the Hole but may get damped or phaseshifted due to the different Acustic Impedance inside the Hole,  compared  to the surrounding Air. Same Effekt You have in a Transmissionline ,Bassreflexchasis  ( Helmholzresonator ) where the Phase sees a 180 Degree Phaseshift at the  Transition from the "Hole " to the surrounding Air. The Dampingeffect You find also in a modern  Fiberfree Velocity Arbsorber  build with microperforated Polycarbonatfoil,  instead of the traditional Fibermaterial , where the Soundwave is damped ( transformed  into Heat ) via Friction of the Air in the supersmall Holes that has a much higher " acustical Resistance " than the surrounding Air. I don t know if at all or how strong this Effect is present in a 5mm Hole.
But I am really not sure If all this Information are important for the Analysis of the acustical Effects of a Headbasket. Hope I didn t confuse You.
Greatings
Lothar

 

[kooma]

Hello,
Everything shorter than the Barrier get s reflected.  It s not a Matter of the Holesize but the solid Space between the Holes where the shorter Wave get s reflected. But this is only a  more or less theoretical , imperical Analysis, in Reality Things are different. All Modells of Acustic Theory have there  Problems to explain everything, so all are wrong  from a Science View. Larger Wavelenght pass the Hole but may get damped or phaseshifted due to the different Acustic Impedance inside the Hole,  compared  to the surrounding Air. Same Effekt You have in a Transmissionline ,Bassreflexchasis  ( Helmholzresonator ) where the Phase sees a 90 Degree Phaseshift at the  Transition from the "Hole " to the surrounding Air. The Dampingeffect You find also in a modern  Fiberfree Velocity Arbsorber  build with microperforated Polycarbonatfoil,  instead of the traditional Fibermaterial , where the Soundwave is damped ( transformed  into Heat ) via Friction of the Air in the supersmall Holes that has a much higher " acustical Resistance " than the surrounding Air. I don t know if at all or how strong this Effect is present in a 5mm Hole.
But I am really not sure If all this Information are important for the Analysis of the acustical Effects of a Headbasket. Hope I didn t confuse You.
Greatings
Lothar

You are absolutely right, i might be more confused;
should change the topic name to headbasket design for idiots
For indirect sound i get it, but for direct sound coming straight towards the hole i just Dont get.. I Do some more reading tomorrow

 

[tubestation]

Hello  Kooma,
Acustic Theory is a very complex and difficult Subject. So don t panic If You don t  understand everything Right now. Just to see how some People see the World , have a Look here
http://www.win.tue.nl/~sjoerdr/papers/boek.pdf
I don t want to shock  but  I want to show You that it is not easy to get a complex Understanding. Don t put Yourself under Pressure  and take Your Time  to learn If You are interested. It s good to start from the Beginning, with the easy to understand Things.
For building a good working Microphoneheadbasket You don t need to dive too deep into Theory, I think.
Just build several different prooven Designs and compare with Your Ears. People tried to meassure inside Headbaskets with fancy Meassuringequipment  but didn t get  clear,  calculateable Results as far as I now.
Dig some different Holepatterns into Your Mictube, If You have Hum Issues, install a Second  Screen inside.
Try different Wiremesh  Holepatterns  and give it a listen.
Much more Fun than studying Mathematics and Physics., i  think.....
Greatings
Lothar

 

[kooma]

Hello  Kooma,
Acustic Theory is a very complex and difficult Subject. So don t panic If You don t  understand everything Right now. Just to see how some People see the World , have a Look here
http://www.win.tue.nl/~sjoerdr/papers/boek.pdf
I don t want to shock  but  I want to show You that it is not easy to get a complex Understanding. Don t put Yourself under Pressure  and take Your Time  to learn If You are interested. It s good to start from the Beginning, with the easy to understand Things.
For building a good working Microphoneheadbasket You don t need to dive too deep into Theory, I think.
Just build several different prooven Designs and compare with Your Ears. People tried to meassure inside Headbaskets with fancy Meassuringequipment  but didn t get  clear,  calculateable Results as far as I now.
Dig some different Holepatterns into Your Mictube, If You have Hum Issues, install a Second  Screen inside.
Try different Wiremesh  Holepatterns  and give it a listen.
Much more Fun than studying Mathematics and Physics., i  think.....
Greatings
Lothar

Thanks!
Have to take a closer look of that paper,  some of it seems remotely familiar but towards the end it's like reading klingon

But your pragmatic solution seems best for now, I'll post my findings here when I get something done.