Topic: Building an Impedance Tube (Read 3897 times)

stickman · « **on:** October 16, 2006, 02:29:35 AM »

It seems to me as though it should be possible to build an Impedance Tube for testing materials and the like. Does anybody have plans? materials, diameters, all the rest...

Ethan Winer · « **Reply #1 on:** October 16, 2006, 05:32:22 PM »

Sticks,

I know only a little about this, but hopefully it can help.

The lower in frequency you want to measure to, the longer the impedance tube must be. The impedance tube at IBM's acoustics lab I use is 14 feet long (I think) and it can get down to 70 Hz accurately. The construction itself needs to be massive and rigid, though that's probably not as difficult as coming up with the hardware and software to create the signals and analyze the results. I have no idea how that part is done, but Dr. Matt Nobile, head guy at IBM, says it's fairly straightforward. Yeah, sure, for him maybe. Shocked

I'll be quite interested to see if Fran or anyone else can explain more.

--Ethan

franman · « **Reply #2 on:** October 16, 2006, 07:41:31 PM »

Lars you have any material on this? I don't have any experience or any serious background in this subject... Cool

stickman · « **Reply #3 on:** October 16, 2006, 08:37:10 PM »

i figured that just a brass tube (PVC probably not rigid enough right?) with a couple of flush mounted mics up one end and a flush mounted speaker up the other end would be easy enough to make. i am curious on the specifics though and what it actually takes to make an accurate one.

L_Tofastrud · « **Reply #4 on:** December 01, 2006, 05:34:36 PM »

I don't really know anything about this.

I know the "master Handbook of Acoustics" mentions this but I think it's a short chapter...

What do you wish to measure? Impedance tubes are only useful with porous absorbers and another issue I know about is that the absorbtion measured will only be valid for sound coming in 90 degrees on the absorber.

Maybe it would be worth searching trough some AES documents?

Regards
Lars Tofastrud

stickman · « **Reply #5 on:** December 05, 2006, 07:32:51 PM »

thanks for bringing this back up Lars.

I read up a bit on them and figured it would be relatively easy to make one (pipe, plunger and couple measurement mics). Was curious if anybody had tried to make one and if they had any useful results but it seems it is not the case.

i guess there is enough published data around that nobody needs to test materials themselves? i dunno

R/E/P Community

Author Topic: Building an Impedance Tube (Read 3897 times)

stickman

Building an Impedance Tube

Ethan Winer

Re: Building an Impedance Tube

franman

Re: Building an Impedance Tube

stickman

Re: Building an Impedance Tube

L_Tofastrud

Re: Building an Impedance Tube

stickman

Re: Building an Impedance Tube