>> This is probably a hare-brained idea, but I'm curious. >> >> Are any of you aware of anyone who has developed computer software >> to visual >> the beating of coincident partials in real time? For instance, the >> user >> might enter the names of two pitches, play the notes on a piano, >> and see the >> beats he is hearing displayed as visual pulses on the screen, maybe >> even >> with the beat speed of each set of coincident partials displayed. >> The >> objective the program would be to speed the training of the ears/ >> aural >> awareness through visual reinforcement. >> >> With all the software development happening "out there", I can't >> imagine >> that I would be the first to come up with the idea. Maybe someone >> has >> explored it and found it doesn't actually help anyone, but I'm still >> curious. >> >> Floyd Gadd >> Manitoba Chapter Hi Floyd, This is not a hare-brained idea - many of us have thought of it, but, to my knowledge, none of us has taken the time to implement it in a stand-alone version. If you have a DAW (Digital Audio Workstation), you can implement it yourself on an note-by-note basis without too much trouble. Just in case you aren't familiar with the DAW, it is simply audio software that runs on a computer, and allows you to record, edit, and mix multiple tracks of audio (and usually MIDI and often video, as well). The GarageBand software that comes with a Mac qualifies as a simple DAW, and on the PC, Reaper is a free or shareware DAW. So, if you have a laptop, this doesn't have to represent an expense if you want to play around with it (though I haven't done this using either of those programs, so I can't say for sure that it will work exactly as I describe below if you go the free route). Here's how you get it going: 1) Set up a track to monitor a microphone input (can be the built in mic in your computer, or a better mic). This usually involves record- enabling the track, and possibly setting monitoring options via a menu as well. Watch out for feedback - if you're going to monitor (listen), monitor with headphones only, and turn down the output level of your computer's internal speaker (or any speakers you have hooked up to your computer) to zero if necessary! 2) Add a bandpass filter to that track (a bandpass filter cuts out lower and higher sounds than a selected band). This is often done in a window that resembles a mixing board, by adding a plug-in near the top of the channel representing that track. A parametric EQ can be configured as a bandpass filter if you can't find a dedicated bandpass filter. 3) Edit the bandpass filter settings - set the filter bandwidth, Q, or resonance (three words for the same thing, often used interchangeably) to a small value, meaning a narrow band. If the bandwidth is wide, a frequency response graph for the audio passed through the filter looks like a bell (open side down). If the bandwidth is narrow, it looks more like a spike or needle. That's what you want. 4) Arrange the display window(s) of your DAW (if necessary) so that you can see a meter representing the output of the track you just set up. The bigger/more-segmented/higher-resolution your meter is, the easier it will be to see the beating. If you know your DAW (or if you get a bit of help from someone who does), the first four steps should take five minutes or less, and are a one-time expenditure of time (assuming that you save your DAW document). Now, the only part that you must change manually while you play the piano: 5) in the "center frequency" text box within your DAW's bandpass filter, type in the frequency value (center frequency) for the coincident partial pair you want to hear/watch beating. It's probably easiest to use a frequency chart. We all know about inharmonicity, and that predicted frequency values from a chart are not going to match real-world observed piano partial frequencies. However, if you set your filter bandwidth to about 100 cents (which will translate to +/- 50 cents), you'll probably catch the partial coincidence. If not, nudge it up (in the treble) a bit. That's it - you should be able to play the selected notes and watch the meter moving up and down in time with the beating (some meters might move L-R instead). If you monitor (listen to) the output of the DAW (using headphones to avoid feedback), you should hear only the coincident partial loud and clear. As you switch from coincidence to coincidence, just repeat step 5. Example: If you want to see/hear the 3:2 beat rate of the P5 A2-E3, the coincident partial is E4, so type in 330. If you want to see/hear the 6:4 beat rate of the P5 A2-E3, the coincident partial is E5, so type in 660. If you want to see/hear the 9:6 beat rate of the P5 A2- E3, the coincident partial is B5, so type in 990 (or type in 993 or something around there if you want to account informally for inharmonicity). You should hear/see three distinct beat rates: slow, medium, and fast. All three happen simultaneously in a reasonably healthy piano, and this can help you to sort out what you're hearing. Totally off topic: Didja ever notice (thanks, Andy Rooney) that the three coincidences (E4, E5, B5) are starting to form their own harmonic series? In fact, every individual partial can be thought of as the fundamental of a new harmonic series which is a subset of the harmonic series of the fundamental that "spawned" that partial. When I realized this, it helped me to sort out quickly and without much thought the multiple coincidences (and simultaneous beat rates) that I was hearing while tuning. Okay, back on topic. After writing the above, I seem to recall from watching Rick Baldassin teach at a conference that the Accu-tuner can output a bandpassed signal at its current "listening frequency." I don't have an Accu-tuner, but if my memory is correct, then the late, great Al Sanderson thoughtfully included an audio output of the bandpassed coincident listening frequency to make hearing beating easier. If this is so, then you can simply hook up the output of the Accu-tuner to any device (hardware or software) that includes a VU (level) meter, and you should see the beating reflected as a bouncing of the meter. Much easier, as you don't have to type in the desired coincident partial frequency. Maybe an Accu-tuner owner/user can verify or refute this.... I used this technique (using a DAW) when I was starting out, and though I thought it was neat, I found that I could hear the coincidences clearly enough and separately enough that I didn't really need the visual reinforcement. But you can give a try. Joe DeFazio Pittsburgh -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090103/416a0832/attachment-0001.html>
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