Designing physics experiment (vibration)

[Gregathon]

Hello all,

I'll start by explaining that this is my first post, and I have very little engineering and mechanical knowledge. I am currently completing my phd in neuroscience so the purpose of this post is to seek information to indulge in some of my hobbies :)

I am designing a machine with which I plan to observe sound wave properties. It is important to me that these observations come from a live model, rather than using software replication.

Putting it simply, I want a vertical rod (metal, between 1-2ft long, 1/4inch diameter) to vibrate. I would like to be able to control the frequency as well. I have brainstormed ideas involving oscillatory motors or by use of speakers.

I am currently learning welding techniques and have access to tools for cutting as well. Thanks!

 

[russ_watters]

Welcome to PF!

What frequencies are you looking to produce? What you are describing sounds like just a big tuning fork, but recognize that a tuning fork has one natural frequency that is dependent on its size and material properties. So there are will be some limitations on the frequencies you can easily produce unless you are willing to change the properties. You could, for example, clamp the bar to change its length for different frequencies -- think of it like a guitar but with a solid string.

 

[Gregathon]

Welcome to PF!

What frequencies are you looking to produce? What you are describing sounds like just a big tuning fork, but recognize that a tuning fork has one natural frequency that is dependent on its size and material properties. So there are will be some limitations on the frequencies you can easily produce unless you are willing to change the properties. You could, for example, clamp the bar to change its length for different frequencies -- think of it like a guitar but with a solid string.

Great consideration, thank you! That all makes sense. Since this project is still very preliminary, I would like to imagine something like a motor in which I may have the ability to remove the rod, replacing it with another of the same size (but different material). The rod itself will connect to other objects, however that portion of the project is not my priority at this point.

As far as which frequencies I desire to send through the rod..

I want to be able to emulate chromatic scales. It would be fantastic to be able to measure in Hz, say I want 440 passing through, providing me with an A. For example, being able to go A to G in a single octave, or being able to produce A in 6 different octaves. I would need to do more research into what materials to use.

I already tried using an apparatus in conjunction with my 30 watt guitar amplifier, working purely on sending the vibration through the rod, and having precise control over "what" the sound was. It was not strong enough for my purposes.