Risset-shepard Effect

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Risset-shepard Effect

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Trebor	Oct 19 2006, 09:42 PM Post #1
Virtuoso Group: Members Posts: 4815 Joined: 12-July 05 From: Bucks/Oxford Member No.: 4133	Heard about this the other day in Physics and looked up a bit more about it. This is like the audio equivalent of Escher's never-ending staircase - successive tones that seem to always to go down in pitch forever, without getting any lower. Risset accelerando Wikipedia article - click the sound file at the bottom for a glissando I thought it was quite cool, it fools the ears into thinking they're hearing something which they aren't. And out of general curiosity, could someone with perfect pitch tell me if it works for them. edit - this one's quite nice too

YetAnotherPianist	Oct 19 2006, 09:49 PM Post #2
Virtuoso Group: Members Posts: 6692 Joined: 18-January 05 From: Sofa; occasionally, piano stool Member No.: 2978	Yes, it works. Although, if I fight it, I can jump up and down the octaves of the notes I'm hearing.

Trebor	Oct 19 2006, 10:07 PM Post #3
Virtuoso Group: Members Posts: 4815 Joined: 12-July 05 From: Bucks/Oxford Member No.: 4133	Oh okay. Just wondered if it would make a difference (IMG:style_emoticons/default/ph34r.gif)

petrat	Oct 19 2006, 10:21 PM Post #4
Unregistered	I listened for a while, before it got too annoying and could only hear it rising. What is it supposed to sound like? I have not read the article yet.

Trebor	Oct 19 2006, 10:22 PM Post #5
Virtuoso Group: Members Posts: 4815 Joined: 12-July 05 From: Bucks/Oxford Member No.: 4133	It's supposed to sound continually rising but it never goes out of your range of hearing, because it's not actually rising the whole time - you just think it is.

sarah-flute	Oct 20 2006, 12:11 AM Post #6
Maestro Group: Members Posts: 25735 Joined: 14-December 04 From: Insomniaville Member No.: 2729	I'm a bit confused, it's supposed to sound like it's continually rising or falling depending on which one you're listening to, yes? To me it sounds like a series of rises or falls, for example dropping from high to low gradually, then a leap, then another drop... (IMG:style_emoticons/default/unsure.gif) the descending glissando is, to my ear, more effective and smoother, but I can hear octave jumps or something happening in there, and can definitely hear that the falling starts from higher up every so often... um... that makes no sense... (why am I not in bed??!) I think I can hear what the illusion is but I can also quite clearly hear how it's done if that makes sense... The one with the beat I would say the "jumps" are more obvious. I have to say I don't understand the science at ALL (IMG:style_emoticons/default/wacko.gif) maybe I should try again tomorrow... I can't make the Wiki one work... it won't play ogg files on my pc (IMG:style_emoticons/default/sad.gif) Interesting....... (IMG:style_emoticons/default/huh.gif) is slightly confused I wonder if knowing there is a "trick" makes it easier to pick out?

jm-hamilton	Oct 20 2006, 08:11 AM Post #7
Virtuoso Group: Members Posts: 2217 Joined: 4-January 05 From: By the sea Member No.: 2857	I just listened to the first one. It sounded to me as thought the pitch rose and then the octave below was gradually introduced at the same time, then the upper pitch gradually disappeared and left the lower pitch rising. Couldn't get the second one to play

Trebor	Oct 20 2006, 04:58 PM Post #8
Virtuoso Group: Members Posts: 4815 Joined: 12-July 05 From: Bucks/Oxford Member No.: 4133	You both obviously have better ears than me. That is (I think) how it's done, playing descending octaves and then jumping the bottom one up when it gets low. Maybe it works better if you're not listening too hard... (IMG:style_emoticons/default/ph34r.gif)

sarah-flute	Oct 20 2006, 06:43 PM Post #9
Maestro Group: Members Posts: 25735 Joined: 14-December 04 From: Insomniaville Member No.: 2729	OK I guessed that must be how it was done, from what I heard, something like that. The science bit was way over my head! I'll have a listen today now I'm a bit more awake - see if it makes any difference... edit: Just been reading the Wiki article again, I think that one with the beat is also supposed to sound like it keeps getting faster as well as higher - to me that does sound like it's getting faster but then suddenly I think "hold on, it's got slower" but I can't hear the transition, or haven't managed to - anyone else? With the glissando one I can just about make myself hear the illusion but actually seem to have to concentrate to hear it, rather than the other way around.... (IMG:style_emoticons/default/unsure.gif) (IMG:style_emoticons/default/ph34r.gif) (IMG:style_emoticons/default/wacko.gif)

Oddball	Oct 20 2006, 08:43 PM Post #10
Maestro Group: Members Posts: 11091 Joined: 12-October 04 From: Market Harborough Member No.: 2310	You can hear, if you try, on the second one the higher frequency cutting in.

sarah-flute	Oct 20 2006, 08:56 PM Post #11
Maestro Group: Members Posts: 25735 Joined: 14-December 04 From: Insomniaville Member No.: 2729	I can hear that - it's letting myself hear the illusion I have a problem with (IMG:style_emoticons/default/laugh.gif) Maybe I'm just weird..... (IMG:style_emoticons/default/wacko.gif) (IMG:style_emoticons/default/tongue.gif)

ben_walker446	Oct 20 2006, 08:56 PM Post #12
Virtuoso Group: Members Posts: 4860 Joined: 10-December 05 From: Stoke-on-trent Member No.: 5524	QUOTE(Trebor @ Oct 19 2006, 10:42 PM) Heard about this the other day in Physics and looked up a bit more about it. This is like the audio equivalent of Escher's never-ending staircase - successive tones that seem to always to go down in pitch forever, without getting any lower. Risset accelerando Wikipedia article - click the sound file at the bottom for a glissando I thought it was quite cool, it fools the ears into thinking they're hearing something which they aren't. And out of general curiosity, could someone with perfect pitch tell me if it works for them. edit - this one's quite nice too What is the bottom link supposed to be? I just heard a really low murmur (sp?) On the first one it sounded like it was getting faster but when I started listening it sounded the same. I heard the pitch go higher then drop the octave and start again but there was still the other note ascending, but then the other note got too high and went ! I couldn't get the second one to work

sarah-flute	Oct 20 2006, 09:08 PM Post #13
Maestro Group: Members Posts: 25735 Joined: 14-December 04 From: Insomniaville Member No.: 2729	The last link is very quiet - I had to turn the volume up to hear it (it's a gliss)

sneekymum	Oct 20 2006, 09:45 PM Post #14
Advanced Member Group: Members Posts: 869 Joined: 18-May 06 Member No.: 6958	this is interesting - the effect of sound resonance on rice

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