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Old 16th August 2012, 11:04 PM   #26481
DF96 is offline DF96  England
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Does that surprise you?

What answer would you give to your own question?

OK just seen your new post. I would expect to see a set of frequency components, spaced in frequency by 1/beat, centred around the drum fundamental and its overtones. There could be components at lower frequencies.

Note that to measure 'a frequency' you need it to last for an infinite time, so a real drum does not have a frequency but it does have a waveform so it also has a Fourier transform.

Last edited by DF96; 16th August 2012 at 11:08 PM. Reason: extend
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Old 16th August 2012, 11:04 PM   #26482
jcx is online now jcx  United States
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windowing in the frequency domain gives a filter in the time domain

truncating = a "brick wall" filter

dropping the ten lowest frequency components in a 20 second record's fft, then doing the inverse fft gives a 0.5 Hz brick wall high pass filter

dft allows "fast convolution" filters - for really long fir filters you can save multiplies


does a 20 Hz hi pass analog filter affect the drum beat?

Last edited by jcx; 16th August 2012 at 11:07 PM.
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Old 16th August 2012, 11:04 PM   #26483
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Temp posting problems.

Last edited by simon7000; 16th August 2012 at 11:07 PM.
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Old 16th August 2012, 11:06 PM   #26484
RNMarsh is offline RNMarsh  United States
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Thats good stuff. HOWEVER, the comments to it are great as well... as they are here. The mistake is to be literal about left and right and what that view was actually (a 2D construct). It points out how the mind will fill-in the missing info - as we are known to do with listening.

Some people couldnt see it rotate at all or in one direction, only. What That means is up to individual exploration. But, there were many different affects indicated for the test viewing. What it means EXACTLY is not the real issue - left-right brain dominance- but that we dont all see things the same way. nor hear them the same way. As I learned from the deaf -- hearing is learned or rather interpreting what you hear is learned. Some learn more than others... some have differing spatial perspectives and abilities... even between sexes. hearing must fall in there somewhere. Thx for the extra info.-RNM

Last edited by RNMarsh; 16th August 2012 at 11:09 PM.
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Old 16th August 2012, 11:12 PM   #26485
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Originally Posted by Wavebourn View Post
When I evaluate some audio system I close eyes and try to imagine real sources of sounds. If it is easier, the system is better. If It is harder, and I still hear speakers, amps, and it is harder to imagine that they don't exist, it is worse.
Though you don't have to close your eyes. The key word you used was "try", when a system is not quite there then you do have to try, the more effort required the "worse" the system, and then you get into the realm of classic listening fatigue, as in, I can only listen for half an hour before I had enough -- the ear/brain is exhausted by the amount of energy that has to go into decoding the musical message, bypassing the haze of distortion imposed by the playback system. There is a level of quality of replay where the word "try" becomes irrelevant, the body is at complete ease while listening, the realm of true "high end" sound ...

I have a nice bundle of CDs that I use for testing this capability, one particularly useful is a collection of early 30's famous swing orchestra tracks. Play this at realistic volumes, a conventional system creates a pretty awful, scratchy mess. At the next level up the sound starts to come to come together, you get soundstaging, depth, ambience, but the tonality is still extremely wearing. Finally, at the top of the tree so to speak, you can "see" the musicians in the rows of the recording space, and the tone of the brass section comes through completely cleanly, there is no difficulty "perceiving" the instruments as being "there".

This is all psychoacoustic of course, but demonstrates how powerful the mind is in unraveling a complex sound message if you give it the right material to work with ...

Frank
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Old 16th August 2012, 11:15 PM   #26486
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Quote:
Originally Posted by jcx View Post
windowing in the frequency domain gives a filter in the time domain

truncating = a "brick wall" filter

dropping the ten lowest frequency components in a 20 second record's fft, then doing the inverse fft gives a 0.5 Hz brick wall high pass filter

dft allows "fast convolution" filters - for really long fir filters you can save multiplies


does a 20 Hz hi pass analog filter affect the drum beat?
Yes that yields a high pass filter.

As to high pass filtering the drum beat I suspect you do lose something!
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Old 16th August 2012, 11:26 PM   #26487
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Originally Posted by fas42 View Post
Though you don't have to close your eyes. The key word you used was "try", when a system is not quite there then you do have to try, the more effort required the "worse" the system, and then you get into the realm of classic listening fatigue, as in, I can only listen for half an hour before I had enough -- the ear/brain is exhausted by the amount of energy that has to go into decoding the musical message, bypassing the haze of distortion imposed by the playback system. There is a level of quality of replay where the word "try" becomes irrelevant, the body is at complete ease while listening, the realm of true "high end" sound ...

I have a nice bundle of CDs that I use for testing this capability, one particularly useful is a collection of early 30's famous swing orchestra tracks. Play this at realistic volumes, a conventional system creates a pretty awful, scratchy mess. At the next level up the sound starts to come to come together, you get soundstaging, depth, ambience, but the tonality is still extremely wearing. Finally, at the top of the tree so to speak, you can "see" the musicians in the rows of the recording space, and the tone of the brass section comes through completely cleanly, there is no difficulty "perceiving" the instruments as being "there".

This is all psychoacoustic of course, but demonstrates how powerful the mind is in unraveling a complex sound message if you give it the right material to work with ...
I respectfully disagree. In one case it is "Try to not hear the system", in another case it is "Try to hear the system", but in both cases it is "Try", because it is evaluation

However, when you speak about listening... But it is hard for a designer not to evaluate, even when listening.
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Old 16th August 2012, 11:43 PM   #26488
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Originally Posted by simon7000 View Post
As to high pass filtering the drum beat I suspect you do lose something!
Now I think you're being deliberately obtuse. Never start and stop your CD player, you could be losing something.
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Old 16th August 2012, 11:57 PM   #26489
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Mr Simon thinks there can be a black hole in a discontinuity, despite matching rms values ?
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Old 16th August 2012, 11:58 PM   #26490
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So, to take it a little further or to kill a dead horse --> We get a group of men and women to look at this rotating image..... and they have different descriptions of what they see. One will know exactly what it actaully is (2D etal). but the other people do not and may never see it that way or any other way except how they see it. They might look at it with one eye or side ways and get yet another view. But it isnt the actual view of the test. So, Which is the 'real' view. the actual test or the viewing of the group as expressed by the individual viewers?

The FFT for example is what it actually is and does what it does..... It doesnt correlate to what a group of people might say it sounds like. What you see on the display - harmonics - doesnt really tell us much about hearing nor listening perceptions. Not anymore than a color analyzer tells us what we percieve or experience in viewing an image. So, yes, its a tool. But not a very good one for what individuals hear. It isnt unlike the rotating figure. A test instrument isnt going to predict what You will see or think you see when observing that rotating figure.

lets see if we can find the blind spots and fill it with tests that will show a more complete picture. Or, do as I do... take all the viewers (listeners) comments and try to understand it and accept it as if real and sometimes different from others and move on. Because as F.Toole said (in a different context) " In the end the ear wins." -Thx, RNM

Last edited by RNMarsh; 17th August 2012 at 12:12 AM.
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