Re: Bell T and Shepard tones

Hi Sarn,

> I looked up the information dealing with Sheprard's tones and bell
> frequencys, and altho I have heard Shepard's tones, whith the timbral
> content related to the octaves, if you listen REALLY closely, I noticed that
> this "M C Esher Staircase like effect", (Sorry guys, I know of no other was
> to describe it) can be heard to "break", --and the sound to me, anyway,
> suddenly seemd to ZIP up to the origional frequency.

Yes, it can do that.

The lowest partial starts very quiet at the beginning of the scale, several octaves down.

May indeed start with volume of 0, i.e. not present on first note, only comes in on
second.

Then goes up the scale, getting louder as it goes, then once you've gone round
once, it turns into the second partial an octave higher.

The Shepard tones are very unusual in the way they are made up, if made from
sine waves, as the only partials are the octaves.

So it is possible, listening really closely, to hear the same partial go all the way up
the "staircase", tracing out all the partials in all the tones on its way.

I may do a demo of this some time, by playing the partial, then the tone, then the next
step of that partial, and so on all the way round the circle, and keep going from the
lowest partial when it first enters in, all the way up to the highest when it vanishes.

Then, if you listen closely, you can hear when the lowest partial comes in each time.

But it is usually a really quiet note very low in pitch.

Same with highest partial, has to vanish at some point, but is really quiet for the
note before.

When you play it fast also, the effect tends to break down a bit, not sure why,...

I have idea of doing a shephard like tone, but instead, use, say, partials
8 to 16 of the harmonic series at all the octaves.

Then use same envelope as before.

Timbre may be interesting, and break point less noticeable, perhaps, have
to see,...

In fact, I'll add this to FTS 1.10 for the future, along with everything els.

Fits in, as I also plan to add a shepard tone custom voice. FTS already does
shepard tones in the Scale / Arpeggio playback config (double quaver next
to play scale button) | Asc/Desc | Endlessly ascending / descending.

I'd also be interested to know what the name is for discipline that deals with
acoustical properties of materials.

Robert