carlsson wrote:The sound chip would need to be tuned to some tempered scale to compensate for this, e.g. if there were exactly six steps between each half note, each octave would be 72 steps out of 256 possible. It would offer a range of 3.5 octaves. Fewer steps between each note would offer a wider range if the sound chip can reproduce those frequencies.
Let me rephrase and expand on this reasoning.
Assume a sound chip in which each voice can have 256 different values. 0 for silence, the rest will produce a note of some kind.
Most known sound chips will produce a sound relative to frequency. A low value gives a low frequency, a high value gives a high frequency. As we have seen, the delta frequency between two octaves are fewer Hz the higher note we want to play. It will be reflected in the sound chip as each value will yield an increasingly higher frequency. We get poor note resolution at the upper end, music sounds detuned. The bigger range of possible values, the better resolution. For example the SID chip uses 16-bit values which gives it quite good note resolution.
Now assume a different sound chip which is hard tied to a well-tempered Western music scale. Our friends in Arabia, Africa, Asia and the Carribean may not buy this computer, neither will the folk musicians who rely on micro tonality but that is another matter.
This new sound chip will relate each value to a given note instead of a frequency. Let us assume 255 possible values, and we get a well tempered note every 5 values: 001 = C0, 006 = C#0, 011 = D0 and so on.
That gives us room for 51 semitones, which corresponds to four whole octaves plus three more semitones: C4, C#4, D4. The sound chip can not produce any higher notes than that.
We see that between each semitone there are four frequencies, well spaced out. In practise the frequency distance between each semitone will get smaller as we play higher notes, but the sound chip compensates for us. We can still make quite OK glissandi and other sound effects. I'm not sure about vibrato, if the human ear prefers hearing vibratos at a relative distance to the original note or at fixed number of Hz from the same.
Now assume a third sound chip. This chip is also well tempered, but produces a semitone every third value: 001 = C0, 004 = C#0, 007 = D1 and so on. It gives us room for 255 / 3 = 85 semitones, which is a little over seven octaves. There certainly are 8-bit sound chips capable of playing such low and high frequencies, even if you usually don't use the lowest nor the highest values since (1) the TV or speaker may not be able to reproduce them and (2) you won't hear them anyway. Perhaps your dog will hear them, so this is a sound chip made for dog owners.
With this sound chip, you only have two possible values between each semitone. That may be enough for most people, but glissandi and vibratos may sound like arpeggio effects rather than smooth sweeps.
I hope this lengthy message explains what I meant. All of this is theoretical and has no real point in the discussion. I just wanted to point out that poor note resolution in the upper octaves is not unexpected, given on what premises the sound chips actually produce sounds.