[analogsurviver]

You are a deserving winner

Now say also that keeping the contacts clean and treated by various chemicals specifically designed to seal and protect them against corrosion, wear and tear is not audible - and you are complete.
 
These chemicals were first developed for military - you do not want a plane etc to fail due to poor contatcts - do you ? Regardles if audio is used in home environment or in studio or on location outdoors, it is still far less hostile environment than in a plane. But it helps nonetheless - and is audible. And time consuming - cleaning and treating or re-treating the entire chain can take hours - but worthvile. 

 

[Dobrescu George]

I am going to ask this very complicated question.
 
We have harmonics.
 
We have harmonics caused by ultrasonics
 
we have first order harmonics
 
and we have the normal sines.
 
Now, i do understand most of the things, but:
 
IF ultrasonic harmonics of high order could be audible, and picked up by a microphone and recorded.
 
The normal music we listen to, also has harmonics that are also recorded.
 
So, by the simplest logic circle, if this is true, then when we playback music thorugh speakers, we also play the original harmonics, bust we are also creating harmonics, thing which is true for most types of drive membranes. 
 
So how do we get to not create more harmonics that were recorded? (this would be named as total harmonic distortion, no?)

 

[StanD]

   
Superposition would just mean that the result is the sum of the two sine waves, no? Wouldn't you still need some non-linear mechanism to generate an audible 3kHz tone in this situation? If I play the sum of these two tones through my computer and headphones, I don't hear anything. If I sum up 18 and 19kHz waves (also beyond my hearing ability), I don't hear anything either, not 18kHz, not 19kHz, not 18.5kHz, not 1kHz. If I cranked the volume I'm sure I'd start to hear stuff, but I like my hearing ^_^

Sum is the result of adding the voltages from the two signals, not creating new frequencies which is undesireable and is called Intermodulation Distortion which are sum and difference frequencies. This is useful for radios and is called heterodyne for frequency conversion, nothing good for our context. How did you come up with 18.5 kHz?

 

[OddE]

   
Superposition would just mean that the result is the sum of the two sine waves, no? Wouldn't you still need some non-linear mechanism to generate an audible 3kHz tone in this situation? If I play the sum of these two tones through my computer and headphones, I don't hear anything. If I sum up 18 and 19kHz waves (also beyond my hearing ability), I don't hear anything either, not 18kHz, not 19kHz, not 18.5kHz, not 1kHz. If I cranked the volume I'm sure I'd start to hear stuff, but I like my hearing ^_^

 
-I may be way off (happens all the time when I try to recollect high school physics without putting the theory to the test!) - but the presence of two waves of different frequency in the same medium would lead to - ahem, a beat note? I'll look it up once I've made dinner and put the kids to bed.

 

[lamode]

-I may be way off (happens all the time when I try to recollect high school physics without putting the theory to the test!) - but the presence of two waves of different frequency in the same medium would lead to - ahem, a beat note? I'll look it up once I've made dinner and put the kids to bed.

The amplitude of the combined waves would demonstrate the interference pattern or beat. There is no intermodulation though. That would be the result of IMD in part of the recording chain.

As usual, out batty friend is using arguments which are irrelevant

 

[StanD]

  I am going to ask this very complicated question.
 
We have harmonics.
 
We have harmonics caused by ultrasonics
 
we have first order harmonics
 
and we have the normal sines.
 
Now, i do understand most of the things, but:
 
IF ultrasonic harmonics of high order could be audible, and picked up by a microphone and recorded.
 
The normal music we listen to, also has harmonics that are also recorded.
 
So, by the simplest logic circle, if this is true, then when we playback music thorugh speakers, we also play the original harmonics, bust we are also creating harmonics, thing which is true for most types of drive membranes. 
 
So how do we get to not create more harmonics that were recorded? (this would be named as total harmonic distortion, no?)

Harmonics are multiples of the fundamental frequency, thus are higher in frequency. If ultrasonics are above the human threshold of detection why would one even bother trying to record or reproduce them if they would only waste Dynamic Range? I recommend that you get an engineering or physics text book on signals, harmonics, etc, and read up. I forget but what field are you working to get the Doctorate in?

 

[RRod]

  Sum is the result of adding the voltages from the two signals, not creating new frequencies which is undesireable and is called Intermodulation Distortion which are sum and difference frequencies. This is useful for radios and is called heterodyne for frequency conversion, nothing good for our context. How did you come up with 18,5 kHz?

 
If you play, say, a 440 and a 441Hz sine wave, you hear a 440.5Hz sine wave modulated at 0.5Hz (though we hear it as 1Hz modulation, because I guess ears are weird). At least I don't hear two different tones if I try such an example. Your first sentence is exactly why I asked the question. Is there some aspect of air that engenders an actual audible tone at the difference frequency?

 

[Dobrescu George]

  Harmonics are multiples of the fundamental frequency, thus are higher in frequency. If ultrasonics are above the human threshold of detection why would one even bother trying to record or reproduce them if they would only waste Dynamic Range? I recommend that you get an engineering or physics text book on signals, harmonics, etc, and read up. I forget but what field are you working to get the Doctorate in?

 
 
Sorry, but i am not looking for ultrasonics, i am not going to reproduce those, as it will degrade the signal  quality, in mathematical model, if the sine has the ultrasonics, it is hard to reproduce by the graph, by the DAC, and b the diaphragm of the driver. Contrary to my first beliefs, ultrasonics are not great, the reason we do not hear them is because the ear membrane does not resonate to them. This means that the membrane producing the sound should not resonate either, as the space is closed, it is more complicated with harmonics.
 
I asked that about harmonics because it is kind of a new thing i have to take into account, and i want to maximize the learning curve, i am going to read about harmonics and what to do with them in the weekend, i am pretty curious and excited to learn about harmonics and harmonic distortion. I have only basic knowledge about it now.
 
My PhD is in Mathematics and wave theory, but the exact discipline is none, because my project includes strong knowledge from most fields possible that affect this, as the final result is based on the experimental results, this meaning if there is a difference in SQ between before and after.
 
my field of specialization is mostly mathematical applications. The algorithms i have been working on, take into account only strict mathematical models in ideal theory, how they will actually sound is another matter.
 
Also, today i had a pretty long and interesting work with math professor about transient recovery possibility, and how much the erorr rate will degrade the original signal.
 
My algorithm is fully compativle with the ideal mathematical model, and we could be hearing much closer to reality music very soon!

.Most data is kept within my working place, not within head-fi.

 

[RRod]

   
-I may be way off (happens all the time when I try to recollect high school physics without putting the theory to the test!) - but the presence of two waves of different frequency in the same medium would lead to - ahem, a beat note? I'll look it up once I've made dinner and put the kids to bed.

 
That's my issue. As lamode said, you get an amplitude modulation that is related to the difference, not an actual new tone, unless some non-linear process is going on. Put another way, a long-enough FFT of the resulting signal would just show two peaks at the two original frequencies and no peak at the difference.

 

[StanD]

   
If you play, say, a 440 and a 441Hz sine wave, you hear a 440.5Hz sine wave modulated at 0.5Hz (though we hear it as 1Hz modulation, because I guess ears are weird). At least I don't hear two different tones if I try such an example. Your first sentence is exactly why I asked the question. Is there some aspect of air that engenders an actual audible tone at the difference frequency?

The beat frequency will be 1 Hz or the difference. 440 - 441 = 1. If I remember, when the beat frequency is below 10 Hz, then you will percieve a single frequency that is the average. So in this case you will percieve 440.5 Hz modulated by 1 Hz. As the frequencies become further apart, I believe above 60 Hz, at one point one will hear the original frequencies. This is covered in detail at the below link.
http://www.phys.uconn.edu/~gibson/Notes/Section5_5/Sec5_5.htm

 

[lamode]

Is there some aspect of air that engenders an actual audible tone at the difference frequency?

No, the human ear on the other hand is far from perfect.

 

[RRod]

  The beat frequency will be 1 Hz or the difference. 440 - 441 = 1. If I remember, when the beat frequency is below 10 Hz, then you will percieve a single frequency that is the average. So in this case you will percieve 440.5 Hz modulated by 1 Hz. As the frequencies become further apart, I believe above 60 Hz, at one point one will hear the original frequencies. This is covered in detail at the below link.
http://www.phys.uconn.edu/~gibson/Notes/Section5_5/Sec5_5.htm

 
Thanks. The math from the mother of all reputable sites is:

 
So the frequency of the modulation is 1/2 the difference, but for some reason our ears hear just the difference. But your link says what I thought:
"In contrast to this, the notes at 500 Hz and 625 Hz while beat at 125 Hz. Again, the sound will get louder and softer with a frequency of 125 Hz. But, how will the brain perceive this? Actually, this frequency is far too fast for the brain to follow individual oscillations, and so the brain does not interpret these beats as a periodic change in the loudness of the sound. In fact, under the right conditions, the brain interprets the beat frequency as its own frequency. In other words, you hear a new tone at 125 Hz! This is called a difference tone."
 
That's of course a lot different than the microphone picking up anything at the difference, which is what people seemed to be saying would happen with tones at 80kHz and 83kHz. And since neither of those tones is audible, it makes sense we don't pick up any difference tone either.
 

No, the human ear on the other hand is far from perfect.

 
Blasphemy!

 

[StanD]

Don't blame the ear, it's the brain that does weird things.

 

[lamode]

Don't blame the ear, it's the brain that does weird things.

Technically they both do

 

[Yuri Korzunov]

  Since we cannot hear above a certain frequency, which declines with age or hearing damage, there is no value in reproducing anything above a certain frequency, 20 kHz is considered the high end for most young human beings. There is a downside to allowing these higher frequencies/ultrasonics to come down the chain. They consume power and Dynamic Range that would otherwise be used for sound that we can perceive.

No rely proof what we hear above 20 kHz or it impact to our perception.
 
20 kHz limitation allow expand dynamical range for audible frequencies.
 
Also we avoid ultrasound's intermodulations. It's results appear in audible range.
 
I.e. we must worsen sound for achieving better sound.
 
It positive impact to hearing (subjective perception).
 
Since 2009 my AuI ConverteR does filtration upper 20 kHz.
 
 
Improving quality is not guaranted. However for some systems possible improving.
 
Of course here secret in details - how create the filter balanced by opposite features.
 
Best regards,
Yuri