In response to Mark Kolmar's statement "I disagree with your ideas of how the 20Hz-20KHz figures were arrived at. The inherent limits of the linearity and response of magnetic tape and vinyl discs, I believe, had much more to do with the limited frequency range you describe." Pick up any decent beginning or intermediate text or reference source on musical acoustics and flip to the section on the human ear and its response. Invariably you'll find that the 20 Hz to 20 kHz range is used in reference to human frequency response; that bandwidth is based on averages of many tests on many human subjects. And, of course, from person to person it varies in bandwidth as well as sensitivity within that band according to age, genetic predispositions, health, and environmental conditions. If you don't want to believe the authorities, get thee to a function generator connected to a frequency counter, an oscilloscope, and a playback system capable of the full audio frequency range plus some. Do full range audio frequency sweeps with various waveforms while you're observing the frequency readings of the counter and the amplitudes on the oscilloscope. Relate what you're seeing to what you're hearing and you'll have discovered a great audio learning tool set. Test your family and your friends and come up with your own averages. The combination of vinyl, stylus, cartridge, and preamplifier with special equalization curves results in a frequency response that's all over the map. My earliest childhood memories are of arias sung by Enrico Caruso recorded and played back on 78s on a windup Victrola with a stylus that looked like a sewing needle and truly heavy weight cartridge above it. As you might expect, the narrow bandwidth of that system lived somewhere in the middle of the human frequency response. When I stopped giving it much attention in the late 1970s the vinyl combo had progressed to the point of a 45 kHz capability in the context of the recording industry's quadraphonic experiments. **************** In response to Paul Berolzheimer's statement that "Personally, though I can't hear isolated tones above about 18k except at very high levels, I do think that frequencies above what we actually hear still affect us, & therefore should be present in our recording & reproduction systems for them to be perceived as realistic." Paul's statement that he "can't hear isolated tones above about 18k except at very high levels" shows that he's a very lucky person who's probably been taking good care of his ears. Most people in industrialized societies are fortunate if their range of sensitivity extends beyond 14 or 15 kHz and that'll go south as they age and even more quickly if they abuse their ears. A key point to remember about high frequencies (those above 5 kHz) is that they're not normally used as fundamentals (tones in a melody). The highest note on a standard 88-key piano is around 4.2 kHz depending upon the piano tuner (does he practice stretched tuning?). Only under special circumstances do composers ever use tones in the top octave of the piano to carry a melody; normally they're used for color, effects, flash, fleshing out chords, or doubling lower melodic tones. The psychophysical reason for this is that the formants for the ee sound (as in beet) lie between 2 kHz and 4 kHz; so as a tone's frequency goes toward and above 4 kHz, it tends to sound squeeky or tinkly depending upon its source. Therefore, the value of high frequencies is not so much as fundamentals as it is for providing a sound with life, color, spectral dynamism, and ultimately realism according to the way the high frequencies interact with other spectral components to create tonal reinforcements and multiple levels of combination tones. Ron Pellegrino
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