How to produce specific audio tones?

July 30, 2009 9:27 PM

Is there an instrument or gadget that will allow me to produce multiple tones of specified frequency simultaneously?

I just finished reading much MeFi-recommended "This Is Your Brain On Music". Levitin talks about a lot of things I would like to experiment with. Most of these can be tried out on a regular keyboard: perfect fifths are great, difference between major/minor chords, etc. However, the things he says to explain why we have the 12 tone plus octaves system depend on trying out tones not on a regular keyboard and concluding that they suck.

One thing I would love to try is the perfect half-octave: two tones with a frequency ratio of square root of 2 to 1. That combination is supposed to be particularly unpleasant but (or hence) not available on a keyboard. Or what happens if we displace the whole 440 Hz based progression by one based on some random frequency: do major/minor chords still carry similar meaning?

Is there a way to do these things that doesn't cost more than a few hundred bucks? I suppose I could download some software for this, but I'm not sure if the tones produced by the puny speaker on a Mac will be reliable enough.

posted by shazzam to media & arts (12 comments total)

Realistically, software like Audacity + powered speakers (or, if you want to get really fancy, a USB audio interface + powered speakers) is gonna be the cheapest & simplest method of experimenting with that.
posted by Pinback at 9:30 PM on July 30, 2009

Sorry forgot to add: if you have read the book, I am exactly the expert-listener-but-ignorant-of-music-theory type he mentions throughout the book, so please keep it simple.
posted by shazzam at 9:31 PM on July 30, 2009

Ask this guy. I have known him for 25+ years and he has been messing around with this kind of stuff the whole time.

Seriously, drop him an email if there isn't anything specific enough on his site. Tell him Julia from Lowell House says hi.
posted by Sidhedevil at 9:45 PM on July 30, 2009

The traditional way is with a monochord. Contrary to the name, they typically have two strings so that you can do exactly the kind of experiments you are proposing.

You could easily hack together a monochord from scraps around the house or whatever. If you want to go high-quality, something like guitar strings would be nice, but you could do perfectly well with some fishing line or kite string, shoebox for sound box, some scraps of wood, etc.
posted by flug at 9:53 PM on July 30, 2009

download this and plug in some speakers. done!
posted by sergeant sandwich at 9:53 PM on July 30, 2009 [3 favorites]

Or what happens if we displace the whole 440 Hz based progression by one based on some random frequency: do major/minor chords still carry similar meaning?

Yes, they carry a similar meaning, but have a different sound quality. For example, consider that many orchestras tune to a different A; anywhere from 440 to 444 (admittedly, not "some random frequency"). Quick and dirty googling leads to this page about flute tuning. Very specific to the flute, but extensive enough to give you a flavor of some pitch issues -- in a very narrow band of frequencies, anyway.
posted by GPF at 9:53 PM on July 30, 2009

One thing I would love to try is the perfect half-octave: two tones with a frequency ratio of square root of 2 to 1. That combination is supposed to be particularly unpleasant but (or hence) not available on a keyboard.

I haven't fully read the book, but are you sure he wasn't talking about the neutral third? The equally-tempered tritone (one piano key less in width than a perfect fifth) has exactly the frequency ratio sqrt(2):1.

If you have a MIDI-capable keyboard, Akoustik Piano has the ability to play quarter-tones and several different tuning systems, which is really a lot of fun to play around with. Unfortunately it'll run you $200 or so, which probably isn't really worthwhile.
posted by invitapriore at 10:02 PM on July 30, 2009

An app called PureData (pd for short) allows you to create any tones you like, and even set them up for midi...
You could midi map out all the third and or quarter tones you want across a keyboard.
it is also math capable, so you can automatically generate the tones you are thinking of...generating scales with weird tunings and so on.

Best of all...it's FREE! (little bit of a learning curve, but if you've got the music part down, the other bits shouldn't be too difficult)

hope this helps.
-AltReality
posted by AltReality at 1:05 AM on July 31, 2009

Any of the freeware or shareware sound editing programs should be able to do this, just generate the desired sine waveforms and mix them together.

There are some neat online tone generator doodads here but I can't comment on whether they are specifically helpful as the site does not work with the version of flash that I have installed which I cannot change.
posted by Rhomboid at 2:09 AM on July 31, 2009

Hi there.

The system of music which uses ratios such as 2:1, 5:4 etc instead of dividing the octave into 12 equal tones is called Just intonation

I would say the simplest way for you to experiment is to get PureData mentioned above, and then get this just intonation sequencer object (not the new python one, scroll to the bottom of the page) No learning curve apart from working out how to install puredata.

If you want to go into it more, I would say get the just intonation primer from here, and look at the other links on the site.

There's a load of commercial and non commercial software you can use to make music like this. You can check out my links here

I was planning to do a post on this sometime to see who's in the woodwork, so if you or anyone wants to get in touch and talk about JI, share linkies etc then drop me a line.
posted by Not Supplied at 3:59 AM on July 31, 2009

Oh btw, it doesn't work by specifying frequencies. What you do is define the base frequency for 1:1 (doh a deer a female deer) say 300Hz or then everything else is a ratio related to 1:1 such as 7:4 for a harmonic seventh or whatever.
posted by Not Supplied at 4:03 AM on July 31, 2009

Praat is free, multi-platform, scriptable, ... You can see a bit of the manual on sound creation here. Lots of resources on the web (mailing list, other people's scripts freely available), and the creator is very responsive. But search hard on the web first, as most newbie questions have been covered previously!
posted by knile at 7:01 AM on July 31, 2009