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Frequencies of music

The Frequencies of Music
Sound is air in motion pushed, pulled, beaten, blown, plucked, talked, or sung into motion. Music is sound's highest achievement, a wonderfully varied mixture of patterned vibrations sent into the air by all kinds of instruments, from a cricket's hind legs to a massive pipe organ.

The frequencies of music, the various repetitions that make up the sound of instruments, are represented somewhat by the charts printed in equipment reviews in various audio/video magazines. But those charts look (and often are) so abstract that it's easy to forget that music is the point of it all. We are trying to remedy that here with the chart below, in which the frequency markings strung out along the bottom baseline are related to the frequency ranges shown above them of the various instruments in an orchestra.

If you've never had a chance to look at the way frequency response corresponds to the sound of instruments, you might want to note first that the divisions along the bottom line of our chart are anything but even. When most people first visualize the frequency range from 20 Hz to 20,000 Hz, they imagine a nice, linear, tape-measure span of measurement, on which the marked increments are as equal as the inch or centimeter markings on a ruler. But when you look at an actual response chart, the measures along the lateral line are definitely not an equal distance apart. In fact, the seemingly "small" span between 20Hz and 40 Hz is actually wider than the 6,000 Hz of difference between 10,000 and 16,000Hz. That's because the vibrations of the heavy-hitting bass instruments of music are ponderous and far apart, while the successively higher pitched instruments going up the scale vibrate faster and faster, and closer together. The frequency scale of music (and all sound) isn't linear but logarithmic which is probably why mathematics and music often seem to go so well together.

Our chart, courtesy of Stereo Review, is fun. It will give you an idea (if you didn't have one already) of where musical instruments lie across the audible frequency range. And there are surprises. Who would have thought, if they hadn't already known, that the bottom of the harp's range went below a double bass's, or that the contrabassoon aced them both? Or that the top of the oboe's range edged out the soprano voice? Or that the piccolo's top note topped the violin's? Or that the same harp that went so low also went right up near the top of the violin's and piccolo's range? Or that the guitar's top note was under 1,000 Hz? Look around the chart for a bit, and we'll go further after that.

The above is from the PSB loudspeaker web site

and go to:

http://www.cco.caltech.edu/~boyk/spectra/spectra.htm




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