Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Using a tuneable audio filter to help you hear beats

I created this video for the CEO of MFJ Enterprises and had it private, but decided it was too cool to keep secret.

http://howtotunepianos.com/using-a-tuneable-audio-filter-to-hear-beats/

Cool. Is the price cool too? Just kidding.

One could argue that when we learn to focus the mind on listening for specific beats, we train our brain to do this kind of audio processing. Accepting that, one could then argue that this learning process could be fast tracked by having such a tool to teach the brain what to do.

Kees

Exactly! I've seen students go from "I can't hear anything" to "Oh ya, now I hear it", from the piano, after hearing the filtered waveform first, in 10 seconds.

I heard the beats from the video audio alone!

Sounds like a good idea for me....I might buy a unit and
try it.

Thanks, Mark.

The problem is mic and amplification. I'm trying to put together a system now.

I tried to point out a mistake to Mark on Google Plus, when I first saw this video there, sometime yesterday, but perhaps my comment didn't post correctly. Be that as it may, I'm surprised no-one here has picked it up!

That filter is not tuned to A5, but A6. When Mark changes the frequency, one can clearly hear it going from A6 to a flattish G6, then E6 and C#6, then back up to A6. Those are partials 5, 6, 7 and 8 of A3.

The beat we hear in the end, is not the normal 5:4 partial match, but in fact the (much fainter!) 10:8 match. This 10:8 partial match is so much fainter than the 5:4 that when the filter is turned off, I don't actually hear it, but only the 5:4, which is also slower! I found that very confusing at first, until I realised that the machine was not actually listening where I was.

Mark is right. I couldn't hear the 10:8 at all when the unit was turned off. It does show how this set-up can pin point coincidental partials we can barely hear.

I may make another video, but I think this one does show how the unit can be used.

Thanks to Mark R. and everyone who has made comments.

There are developers already working in iPhone bandpass filters - there's a DSP framework built-in to iOS that can help with this.

See http://stackoverflow.com/questions/13507321/ios-bandpass-filter etc.

Paul.

Have you tried to record the beats with something like Audacity in order to tag it with an accurate beat rate?

Originally Mark, I thought your method to help with beat rates was very good, but once again (to me anyhow), I think you are making things far too complicated by involving additional electronics and audio filters. Anyone not able to hear beat rates would be far better off just relying on a decent ETD. Perhaps I picked up wrongly on your original post but, I though the idea was focused on aiding tuners to recognise beat speeds and not the beats themselves.

The motivation and inspiration to search out superior teaching resources has come from having too many students who were smart, quick, musical, adept, motivated, and passionate, who could rationalize all the logistical steps need to tune a piano, but were having trouble hearing the beats.

The filter simply shows them what I hear. Their brain tries to "blueprint" that sound and it reduces the time needed to reach a reasonable level of beat recognition.

Relying on an ETD is akin to giving up the dream of learning to tune a piano by ear. I do want anyone to have to give up their dreams if there's something I can do to help make the dream a reality.

But yes, tuning a piano using an ETD is easier if you can't hear beats.

Could you explain? What do you mean by "tagging"?

That is with the use of Audacity.

The brain says "Oh, those are the same."

We record and measure and Audacity says "No they're not!"

We re-listen to the piano and say "Oh ya, maybe they are not."

It is this relistening, or "reaching" that changes the brain. Without that part, the method is useless.

I've been using audacity for several years now for beat rate analysis. I will comment on your other thread explaining how to get accurate beat rate analysis with Audacity. It takes a small bit of math even a 10 y/o can grasp.

Does anyone know where I could go to get something like this designed? I would like an internal amplifier of about 30W or whatever would drive headphones. The filter attenuates the signal quite a bit, so regulate headphone amps are not powerful enough.

To get it to work without the stereo amp I needed a 20W guitar amp, a headphone amp, and 7W computer speakers.

I would like specific input/output types, and custom artwork on the front.

I'm working with the manufacturer and another designer friend, but I am also looking for other options. PM me if you like.

I am trying to get MFJ Enterprises to manufacture a unit that would be more compact and portable, with an internal headphone amplifier. It's not easy. There are a lot of hurdles and I'm not sure it would be worth the trouble.

If anyone else thinks this would be a cool project, please contact MFJ by going to http://www.mfjenterprises.com/HelpDesk/index.php?a=add&company=1 and filling out a comment.

Much appreciated.

IMHO dedicated hardware is the wrong way to go about it. A bandpass filter is easy to implement in software. So all you need on the hardware side is a device with mike-in, headphone-out, and a CPU. Almost everybody owns such a device. Just get the app written and you're done.

A limited trial version will take care of marketing and convincing those unsure of the usefulness of such a tool but they will never buy a hardware device.

I could come up with more arguments for the software solution, but instead will just suggest to Mark to make a table of the pro's and con's of hardware versus software solution broken down into ease of use, customizability, audio quality, upgradability, selling price, design cost, production cost, marketability, other. I believe that would be more convincing than anything I could write here.

As I PM'd Mark already, there are various open source audio processing software packages available, including one of my own, which would make a software implementation a matter of paying a programmer to get it done. The use interface design/implementation would be 80% of the development cost I'd guess.

I didn't mention testing cost because I'd be very happy to volunteer to do that myself, as I think this is a very nice idea.

Kees

Hi Kees,

Thanks for the reply.

You have an audio processing software package of your own? Could you explain what that means? Are you a programmer? Do you sell it? Can I use it to create this app? What language/platform?

Also, I won't disagree with you about the versatility of a software solution, but I want to make two points as to why I would choose it.

1. Piano tuning pedagogy is a tiny market; a niche within a niche. I can not make enough revenue to cover the expenses of this kind of project by selling $1.99 apps on iTunes.

2. The analog dials are cool. An app doesn't have that same feel. The unit is for aural tuning, an analog activity, so the box fits better with this type of activity, IMHO.

Plus, the majority of the design is already done.

Google jass audio.

Kees