Infrasonic Speaker - Need advice for undergrad thesis project - diyAudio
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Old 16th November 2012, 09:55 AM   #1
Rive is offline Rive  United States
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Default Infrasonic Speaker - Need advice for undergrad thesis project

I am a music major in my final year studying experimental and electronic music. For my thesis I am focusing on infrasonic sound and the potential for infrasonic music. Obviously, the first question that comes to mind is, "is it music if you can't hear it?" Well, I'm going to sidestep that question altogether and move onto "what does infrasonic music sound like?"

In order to play with this idea musically, I first need to be able to produce infrasonic tones. I have been studying various basic speaker building DIY sites like this for relavent information, but no one else seems to be interested in solely infrasonic frequencies, only extending their sub ranges as far as possible.

As far as a target frequency goes, I'd like to get as far down as possible with "audible" or "useful" SPL. I'm not so much interested in reproducing anything above say 30 Hz with accuracy. I would at least like to get to 10 Hz any lower than that is bonus in my mind.

Being a college student, my funds are limited, but I can get some money from the school, but not a whole lot, so I will peg my budget at around $800.

I know this task is difficult and impractical, so any help or advice is much appreciated. Thanks!
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Old 16th November 2012, 12:56 PM   #2
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Yeah, I think the problem you have is that ur studying music and not anything engineering or physics.

Also, you need to go out and read the existing literature on this subject.

I kinda hate to say this, and you are not the first to pop up here doing this, but in essence ur asking others to do the thinking for you, and the design work?

I think ur first step is to track down the professors at ur school that do either engineering or physics and talk to them. And, if ur school happens to have a decent library, see what you can get there. Obviously, you ought to be able to find citations online to professional journals and publications, the school library can get you copies.

The only other thing that comes to mind is space - ur likely to need some significant space to implement most standard methods for making sound at those frequencies... and a means to measure it, so you know if ur making anything.

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Last edited by bear; 16th November 2012 at 12:59 PM.
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Old 16th November 2012, 01:09 PM   #3
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Rotary subwoofer if you're not concerned with the musical aspect of it.
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Old 16th November 2012, 01:22 PM   #4
Rive is offline Rive  United States
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I totally hear you, Bear, and I understand your concern, though, I've spent the better part of the last 3 months on this work. I've found plenty of information on infrasound and its alleged psycho-physiological effects on humans, its natural and unnatural sources, even some experimentation with augmenting musical performances with low frequency pure tones on frequencies just shy of the range of human hearing attempting to invoke the strange "chills down the spine" feeling that infrasound has gotten a name for. Trust me, when it comes to documentation, I've got a meaty pile of resources, that's not the issue.

I've been scouring the internet for comprehensive resources dealing with constructing speakers that handle the frequency range that I need, but for obvious reasons, they all seem to fall short when it comes to those frequencies below 20 Hz. Those lowest frequencies are rolled off, but those are the ones I need.

I could easily build a subwoofer, I've done it before, but instead of trying my luck with what little I can find in the way of infra-woofer design, I'm hoping that someone on this forum has some first hand experience attempting to build something similar, who can give me advice and/or share their experience. I don't want to just slap something together, or throw money at the problem. I am seeking advice from experienced builders before charging ahead on my own.

I'm not asking to have the work done for me, I am only asking for help on a project of a rare, and I would hope, interesting nature for enthusiasts.
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Old 16th November 2012, 01:25 PM   #5
Rive is offline Rive  United States
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Quote:
Originally Posted by m R g S r View Post
Rotary subwoofer if you're not concerned with the musical aspect of it.
Unless someone else makes them, the design I've seen by Eminent is far outside of my budget and requires a specialized instillation.
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Old 16th November 2012, 01:47 PM   #6
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You have to make one urself... I think that is the suggestion.

You can find patents...

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Old 16th November 2012, 02:05 PM   #7
gtphill is offline gtphill  United States
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Quote:
Originally Posted by Rive View Post
In order to play with this idea musically, I first need to be able to produce infrasonic tones. I have been studying various basic speaker building DIY sites like this for relavent information, but no one else seems to be interested in solely infrasonic frequencies, only extending their sub ranges as far as possible.

As far as a target frequency goes, I'd like to get as far down as possible with "audible" or "useful" SPL. I'm not so much interested in reproducing anything above say 30 Hz with accuracy. I would at least like to get to 10 Hz any lower than that is bonus in my mind.
For context: I did PhD research in halide-mediated gas-solid reaction thermochemistry in graduate school, have lectured at the undergraduate level, and TA'ed at both undergraduate and graduate level.

I'm with bear above that you've done inadequate review of the existing literature. One of the essences of academic research is learning how to find, navigate, and digest the research literature. For the limited time frame and scope of an undergraduate research thesis, learning to "feed" yourself through a literature review may be the most important thing you will learn.

That said, I know that it can be intimidating to know where to start researching a topic, so here's some useful search terms to get you started:

This is enough to get you started
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Old 16th November 2012, 02:06 PM   #8
Moonfly is offline Moonfly  Spain
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There is a thread on another site (no idea if Im allowed to link it or not) where they discuss the construction of a DIY rotary woofer. Might be worth a look if anyones serious about giving that a go.
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Old 16th November 2012, 04:39 PM   #9
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Here's what I'd do..

Get a couple of those cheap MCM 8" long-throw drivers.

Build a box big enough to stand/sit in.

Mount the 8" drivers in the box, make sure the door is well-sealed, and eq the design flat to as low as you like, with you inside.

Getting SPL at <20Hz in a room is difficult.
Getting it in a relatively small box will be easy, and give you a fair idea of what it'll sound like - put a couple of smallish bookshelf speakers in there too, to cover the rest of the range.

Chris
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Old 16th November 2012, 05:16 PM   #10
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I don't know of any restrictions as far as posting links...
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