Audible Jitter/amirm vs Ethan Winer

Nicholas Bedworth

WBF Founding Member
May 7, 2010
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Maui, where else?
BTW elephants have hearing that goes way, way down into the subsonic. Gotta be careful about your speakers in areas that they frequent. There was a famous National Geographic article some time ago in which an intrepid scientist set up some ultrasonic generators in the middle of some desert, and from miles away, elephants showed up. Because subsonic isn't that localized, the elephants walked right on by the generator and continued to the opposite horizon. Hope they weren't disappointed. :)

Apparently when elephants "freeze" and perk up their rather large ears, they're attending to such subsonic phenomena. In any event, they use subsonics to communicate way beyond line of site.
 
Last edited:
Apr 3, 2010
16,022
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Seattle, WA
You make me worried Nick. Our showroom theater puts out incredible bass so much so that you clothing moves as the sound effects come. So far, I have been worried about hearing damage and people getting sick in there. Now I have to worry about elephants rolling in!!! :D :D :D
 

garylkoh

WBF Technical Expert (Speakers & Audio Equipment)
Building a theater showroom for animals is even more difficult than designing for humans, although audiophiles are notoriously the most difficult animal to pin down. An elephant has a hearing range of 16Hz to 12kHz, but we should design for the ferret which has reportedly the widest range - 16Hz to 44kHz. Or, you could save money on subwoofers and build your showroom for the porpoise which only has a lower range of 75Hz, but an upper range of 150kHz.

http://www.lsu.edu/deafness/HearingRange.html
 

Nicholas Bedworth

WBF Founding Member
May 7, 2010
312
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Maui, where else?
An elephant never forgets...

Or underwater. Certain Individuals showed me designs for a house on Kauai in which the home theater system sound was incorporated into the swimming pool so you could listen underwater. This was a fully-engineered solution, not just a conceptual exercise.

In Bellevue, perhaps some lonesome elk will start wandering around your building in the mating season. :) The elephants can communicate up to about 10 km under ideal conditions such as evening temperature inversion. Apparently they like to share the news of the day before going to bed. Seismic signalling is also employed, but the mechanism is uncertain. They probably can hear down to 5 Hz. The harmonic structure of their vocalizations may allow estimation of distance.
 
I have parrots in my household. They present a particular challenge, trying to balance my appetite for low frequencies vs. their appreciation of quietude.
My cockatiel is just about bomb-proof. He's used to everything.. I can even use the coffee grinder and he'll walk down my arm and try to 'perch' on the grinder dome while watching the coffee beans inside.
Yuki, my Congo African Grey, is new and getting used to noises. Friday night was my first time testing Yuki's behavior in the presence of moderate hi-fi down below. She passed Level 1 testing (125dB peak in the listening room, bass leakage into the parrot rooms much less than that). I have a Molecam trained on her so I can watch her reactions upstairs as I turned up the music down here. I could see her walking down her perch and standing peering over the edge of the cage to look at the floor below. She seemed curious, but not frightened by the noises, so far. As with Clyde, Yuki will probably get used to the music as I ramp up gradually in subsequent sessions.
 
May 9, 2011
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Let's go there and leave this thread to jitter discussion only
Professor Hawksford has produced simulations that shed considerable light on the audible effects of jitter. For those of you who can trundle through the math, here is the paper:
http://www.essex.ac.uk/csee/researc...s/C134 Paper 121st convention (corrected).pdf
For the rest of us, there are samples:

http://www.audioxpress.com/magsdirx/ax/addenda/media/hawksford_jittertracks.zip
Track 0 is the original music, and the following tracks are the resulting amplitude-normalized “distortion” or error signals resulting from the types of jitter as listed:
Track 1: TPDF (triangular probability distribution function) noise-based jitter
Track 2: 2 equal-amplitude sinewaves 44050 and 44150 Hz based jitter
Track 3: 3 sinewaves 50Hz, 100Hz, and 150Hz, amplitude ratio 1:0.5:0.25, based jitter
Track 4: sinewave 0.2Hz based jitter
Track 5: sinewave 10Hz based jitter
Track 6: 3 equal-amplitude sinewaves: 1Hz, 50Hz, and 44100/4 Hz based jitter
Track 7: All of the above 6 jitter sources combined.


I hope the Hawksford paper has not been discussed already, as I lack the patience to read the whole thread, sorry.
 
Apr 3, 2010
16,022
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Seattle, WA
I scanned through and found it exceptionally well written paper. The color 3-D visualizations of jitter are stunning! Will need to find a quite hour or two to read it in detail now.
 
May 9, 2011
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The samples also seem to have been very wisely thought of. They show the effects of correlated and uncorrelated jitter, hum breakthrough, PLL drift etc. To my mind this paper elucidates the major part of the dreaded "digititis", though not all of of it. And it dates from five years ago.
 

Orb

New Member
Sep 8, 2010
3,022
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Definitely going to take my time going through the paper.
Do you know if it was ever linked and discussed on any other forums?
Appreciate it may had some agree or argue about its content on these other sites without really taking time to read it properly but just curious.

Thanks again for the paper.
Orb
 

sasully

New Member
Jun 30, 2010
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Don't have the slightest idea, but it's highly unlikely. Very few people have the required scientific background and they probably do not frequent forums.
Ahem.

http://www.hydrogenaudio.org/forums/index.php?showtopic=73201&view=findpost&p=645122

or back further, the following thread cites Hawksford's simulation work among other attempts to predict/measure jitter audibility:

http://www.hydrogenaudio.org/forums/index.php?showtopic=51322

Hydrogenaudio has been discussing 'what's best' for a long time. It's always a good idea to search there.

(and IIRC, a frequent HA poster is one of Dr. Hawksford's former graduate students.)
 

Orb

New Member
Sep 8, 2010
3,022
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Thanks for the links sasully and forgot about those,
shame though not real "meaty" discussion on the paper and real unfortunately the paper is not on the links anymore in those thread, I really should check the academic links I have myself.
Yes there are a some really great posters on this subject over at HA (mentioned that in the past here) but some of the others technically contributing are not ideal to say the least, but then that can be said of any forum.

Edit:
BTW good to have you back posting, seems to have been awhile.

Thanks again
Orb
 

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