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andymok

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@analogSurviver has been thread banned for continuing to make suspect claims without providing any substantial means to back them up .

The resulting content inspired by his postings all falls below what I want to see here .

You want to make extraordinary claims while presenting yourself as nothing more than another anonymous random person on the internet you need to bring something worth discussing or just drop the argument.

cheers
That's too bad :(
 

bennetng

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Some reality check about this impulse response and bandwidth business.

Unfiltered 2.8224MHz PCM impulse at -6dBFS. The FFT shows a rather low -90dB value because apart from one sample, all other samples are zero.
original.png


I encoded the signal above to DSD64, then decoded to PCM again. Since the original file is already at 2.8224MHz, no upsampling and downsampling is involved. The left panel looks empty, but it is the opposite, it is a selected block of unfiltered waveform with only two amplitude values. On the right panel you can see the impulse (horizontal line) is 6dB lower than the original file, a typical level difference in DSD encoders. Also you can see the ultrasonic noise is much, much higher than the impulse itself.
unfiltered dsd64.png


In order to see the impulse again in time domain, filtering is needed. This filter should not have excessive attenuation below 20kHz. At the same time, it should be able to filter the ultrasonic noise significantly. As you can see there is still some noise after filtering, but at least you can finally see the impulse again, albeit level is much lower than the original one.
filtered impulse.png


Zoomed version to see the impulse and frequency response more clearly. Also +6dB gain is applied to match the level of the original file. As you can see, pretty gross. If the "benefit" of a slow filter is to reduce "ringing", then a filter like this is always ringing, regardless of the presence of an impulse or not.
zoomed.png


Of course, it can be improved by using a steeper filter, at the expense of further reducing bandwidth and the height of the impulse. At higher DSD rates, for example DSD128, everything remains the same, with the FFT plot's x-axis doubled, 20kHz becomes 40kHz, and so on.
steep filtered impulse.png


The same signal as above, with the left panel zoomed. Hopefully these illustrations can give an idea about the real performance of DSD in terms of bandwidth and impulse response.
steep filtered impulse zoomed.png
 
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restorer-john

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So, ultrasonics affect us.
My ultrasonic cleaner makes me feel nauseated after a few minutes of operation. If I wear two sets of earplugs/muffs, it doesn't, or if I throw two thick towels over the top of it. And yet the cat or dog don't seem to care about it.
 

Blumlein 88

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My ultrasonic cleaner makes me feel nauseated after a few minutes of operation. If I wear two sets of earplugs/muffs, it doesn't, or if I throw two thick towels over the top of it. And yet the cat or dog don't seem to care about it.
According to that published paper shouldn't it mellow you out, and after 200 seconds calm your brain waves a little bit?

There was the paper from back when saying high intensity ultrasonics actually can enter the eyes and via the eyesocket vibrate nerves at low level which could effect our sense of well being. Maybe you need safety glasses to stop the effect.
 

BDWoody

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My ultrasonic cleaner makes me feel nauseated after a few minutes of operation. If I wear two sets of earplugs/muffs, it doesn't, or if I throw two thick towels...
That's why I just use soap and the shower.
 

rkbates

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I expect I'll get a flogging here but I'd like to understand where my logic is wrong so please bear with me if it's all been said before. The hair cells in your ears respond to movement in the air. Movement makes me think of rate of change, in a sine wave rate of change is proportional to voltage and frequency. If I my hair cells respond to 1V at 10 kHz, why don't they respond to .33V at 30 kHz (ie same rate of change). I'm not saying that at 30 kHz they can accelerate, decelerate and actually track the 30 kHz, I'm just asking will a high frequency transient have an influence on the perceived sound, and if not why not?
 

gene_stl

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Hair cells and the neurons attached to them don't care about the derivative of air pressure unless its steep enough to blow out your ear drum or dislocate the little bones(malleus incus and stapes) which which probably are part of the high freqency upper limitation in the ear. There are also muscles attached to those bones which if there are loud displacements will very quickly tension themselves to try to preserve your hearing at that greatful dead concert. Look up otoacoustic emissions to read more about that.

The only "research" I have seen that claims perception of ultrasonics is the article from Japan which smelled very funny to me and no one seems to be able to replicate. (EDIT: Oohashi mentioned above and the sponsorship was one of the things that smelled funny to me. Also I don't think it was his regular field of research. It certainly did not influence me. )

One of numerous non scientific experiments I have done with my system is to turn off the tweeter channel which normally runs from 5K up. You hardly notice it. I have turned it off while guests were listening and nobody ever caught me. All the victims were serious audio nuts.
 

Kal Rubinson

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If I my hair cells respond to 1V at 10 kHz, why don't they respond to .33V at 30 kHz (ie same rate of change).
The reason is that both of those frequencies are in the range where the responses are not temporally encoded. Only very much lower frequencies are temporally encoded.
 

restorer-john

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One of numerous non scientific experiments I have done with my system is to turn off the tweeter channel which normally runs from 5K up. You hardly notice it. I have turned it off while guests were listening and nobody ever caught me. All the victims were serious audio nuts.
If someone doesn't notice a non-functional tweeter immediately, on any source (even AM radio), they should forget HiFi, audiophilia and music, and spend their money on a set of hearing aids.
 

rkbates

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The reason is that both of those frequencies are in the range where the responses are not temporally encoded. Only very much lower frequencies are temporally encoded.
So, if my Googling is correct, the auditory neurons can only fire at a maximum of 500Hz and lots of other processing happens to be able to be able to detect higher frequencies. Thanks
 

Kal Rubinson

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So, if my Googling is correct, the auditory neurons can only fire at a maximum of 500Hz and lots of other processing happens to be able to be able to detect higher frequencies. Thanks
Yes. It is a global issue in the nervous system that, inherently, neurons have a limited range of firing frequencies. The need to convey information at higher frequencies requires encoding of the signals and, in addition, various types of encoding are used in many neural systems.
 

gene_stl

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You can find a lot of info on what Kal is talking about by looking up cochlear implants which attempt to prosthetically substitute for the hair cells. They have have gotten quite sophisticated, including some that have electrode arrays going into the brain. (those aren't cochlear but are "auditory" implants)

@restorer-john
I would have agreed with you 100% until I actually did the experiment. I could hear the difference but it wasn't that much. And the system was initially set with a 32 channel RTA (DSP wasn't really available when all this went on)

A very huge percentage of things audio nuts hold to be important are barely audible. Most of them would not get by the proverbial blinded test.
 

Beave

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I expect I'll get a flogging here but I'd like to understand where my logic is wrong so please bear with me if it's all been said before. The hair cells in your ears respond to movement in the air. Movement makes me think of rate of change, in a sine wave rate of change is proportional to voltage and frequency. If I my hair cells respond to 1V at 10 kHz, why don't they respond to .33V at 30 kHz (ie same rate of change). I'm not saying that at 30 kHz they can accelerate, decelerate and actually track the 30 kHz, I'm just asking will a high frequency transient have an influence on the perceived sound, and if not why not?
A sine wave doesn't have to be a voltage. It can represent just about anything - or be a completely abstract mathematical construct.

In the case of sound, it's air pressure, not voltage. Sound, when processed electronically, can be represented by a voltage. But once it leaves a loudspeaker, it's air waves (ie, pressure changes, not a voltage).

So your ear hair cells aren't responding to 1V at 10kHz or .33V at 3kHz or any other voltage. They're responding to changes in air pressure.
 

Balle Clorin

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DSD sounds different than PCM. I've also A/B compared the same tracks in both formats and I can distiguish them. A lot of people prefer the sound of DSD - even PCM converted to DSD. The simple fact that different modulators and filters are used for DSD playback means it sounds slightly different from PCM. It's a matter of taste, not that one is better or more acccurate than the other.

As far as the editing of it, etc., that's irrelevant for listening purposes.

A program like Roon can make changes to DSD by converting it to multibit-DSD and back to one bit. We can argue all day whether that is DSD or not. I'd say it is, as no decimation of the DSD stream takes place. I'm not going to argue that point as it's a pointless argument.

It's been shown with measurements by people like Miska that there are setups and DACs that produce their most accurate non-distorted output when fed DSD and even 2X or 4X DSD. Sorry if that doesn't fit your preconceived ideas and your linked pages from xiph. Sometimes real world facts inconveniently don't match your ideas that you want to crusade about. Your arguments would work better if you don't set up straw men to knock down.
Did you correct for the inherent level difference between DSD and PCM?
 

rkbates

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A sine wave doesn't have to be a voltage. It can represent just about anything - or be a completely abstract mathematical construct.

In the case of sound, it's air pressure, not voltage. Sound, when processed electronically, can be represented by a voltage. But once it leaves a loudspeaker, it's air waves (ie, pressure changes, not a voltage).

So your ear hair cells aren't responding to 1V at 10kHz or .33V at 3kHz or any other voltage. They're responding to changes in air pressure.
All good - I was just trying to join the dots that the change in voltage at the speaker terminals causes the speaker cone to move which causes the change in air pressure which causes the ear drum and other bits to move which causes the hair cells to move and then understand where this stops being a causal linear(ish) chain.
 
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