Coin Sound Analysis Software....

Well Conder101 and jbuck

Here are the NON scientific analysis of the same coin on 2 different surfaces.

I used a 1973 American half dollar for the test.
1 - Dropped the half dollar on a solid maple table.
2 - Dropped the half dollar on a piece of you channel aluminium isolated from the table by a writing pad.

Ya, I know, it isn't very scientific, but it is a start..Remember, Alexander Graham Bell didn't have Skype (ha,ha)

I noticed that there are certain frequencies that are extremely regular no matter what the material.

The frequencies are:

1 - 7000 hz
2 - 12000 hz
3 - 16000 hz
4 - 19000 hz

You are soooooo correct jbuck

Everyone can get their hands on a piece of wood....

BUT, this is far from perfect...Lots of work to do.

Maybe the wood should be isolated with pieces of rubber..Just a thought.

ah.....Conder101...Someone is catching on...Good observation.

You are correct about wood dampening the frequency response of it's own mass.

This (as you said) will allow the frequency of the coin to come trough without secondary frequencies interfering with the results...Yes I can separate them, but hey, why do that when I don't have to.

Maple is a hard wood, but low frequencies...The (almost) perfect material...And anyone can get a hold of a piece of maple and say, cut it to 6x6x1 inch (centimetres in Canada..ha,ha)

Still trialling it for a while...Wish me luck....

Below is an experiment with the same (two 2009 Canadian dimes)coins.
They were both dropped on 1" maple table.

first 2009 dime:
1 - Cursor frequency....21950 Hz
2 - Peak frequency......21755 Hz
3 - peak................77 dB


Second 2009 dime:
1 - Cursor frequency....21816 Hz
2 - peak frequency......21544 Hz
3 - peak................77 dB

That is pretty darn close if you ask me...
Remember, this was done with a built in microphone in a laptop...Not a plugged in mic really close to the coins.

Hi jbuck ...Thanks again for the encouragement.

I will have (what I think is) a standard to go by...(within a week)

Just trying out my new USB microscope with a goose neck to hover directly over the coin at the same height each and every time.

I hope there are people out there that are looking forward to a NEW tool to work with.

Below is a picture of the USB microphone I bought at Best Buy for $35.00 (Canadian of course)

I am very impressed with the results of these tests. Other tests I could envision would be ring tests rather than drop tests. Tests to see how much variability there is between dates in a series. Differences if any in the same date between mints. What I am wondering is could reference spectrums be produced that could be used as another tool for detecting counterfeits? I don't know if that is feasible, but I'd like to see more results. Since I have the laptop and software I guess I should start running my own tests as well. I don't think my laptop has a built in microphone though so I'll have to pick one up.

I love tearing things apart! :D

You may want to look at creating a control or multiple controls. Eventually you'll be able to identify how your reaction material shows up on the graph. If you can isolate the frequencies of your reaction material and then remove them leaving only the coin frequencies you'd really be in business. You have many things to account for trying to isolate the reaction material from the coin, though. Material type and all of its properties and then each individual coin's properties will likely react differently with each reaction material.

Hi guys

I have created a PDF file and a WORD file explaining the coin analysis system...If anyone is interested, please e-mail me and I will gladly send it along.

If no one is interested, that is OK....I will still be creating a database of coin frequencies on my own....

Thanks WERT