As far as phase polarity. Think about a grand piano for example: The hammer always strikes the string from the bottom in an upward motion. Filp the phase and you have this,
Great for a gimmick show but....
Great for a gimmick show but....
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It is the phase interrelation of the various ‘harmonics’ contained that is important to be preserved during recording/playback.
Please provide some reference on this.
Unless you are talking about perceptual hysteresis which has a different explanation.
A quick overview
https://courses.physics.illinois.ed...Notes/P406POM_Lecture_Notes/P406POM_Lect5.pdf
The gimmick is great but hammering the string from the bottom or from the top will make no difference. It will make a difference if you hammer it sideways. (difference in the rate of energy transfer from the string to the bridge, to the soundboard. This affects the pitch and the decay profile of the sound in a complex way)
http://www.jjburred.com/research/pdf/burred_acoustics_piano.pdf
George
PS: A good book (easy reading)
This Is Your Brain on Music: The Science of a Human Obsession: Daniel J. Levitin: 9780452288522: Amazon.com: Books
All amplifiers are tested over their temp range. Most get worse at -55, remember Vbe goes the wrong way robbing head room.
Strongly asymmetric sounds like speech (singing also) and pulse pressure wave generators like kick drums require signal initial peak playback in correct acoustic absolute polarity.
Relative time shifting and level alteration of harmonics can reverse the peak values of the initial and first return halfwaves, and this can fool the senses.
Tone generator instruments are by definition much less assymetric and therefore less polarity important....except for the initial string pluck which is directional.
Dan.
I also appreciate the TI paper, but it does not give me what I really need to know about why IC op amps can sound different. I can hear the differences (open listening) but I can't really explain them.
On another topic, absolute polarity is a tough one apparently, with double blind testing. I know that Dr. Lipshitz could hear it with open listening, but had trouble with double blind testing, although I think that he eventually succeeded at some point. This was decades ago when we addressed this issue in depth. I am surprised how many here don't know about the earlier research. We seem to have to re-invent each topic, as the years go by.
On another topic, absolute polarity is a tough one apparently, with double blind testing. I know that Dr. Lipshitz could hear it with open listening, but had trouble with double blind testing, although I think that he eventually succeeded at some point. This was decades ago when we addressed this issue in depth. I am surprised how many here don't know about the earlier research. We seem to have to re-invent each topic, as the years go by.
So all these waveforms would be ok to invert? They are all asymmetrical! How can that be?
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So a positive transient signal whatever his form will arive as a positive variation of pressure of the same form as far as the treebles are not too much attenuated by the distance) right ? And a negaticve as negative.
Reason why i don't understud your "...because the polarity of signals in the spectrum at the listening position varies continuously depending on wavelength/frequency.".
Tryphon.
So a marching band goes down the street, and they have a guy playing a bass drum, and he is striking both heads of the drum. Which side of the street is the "wrong" side to stand on? What if he is just striking one drum head?
https://docarts-cms.s3.amazonaws.com/asset/image/image-000334-1371606278_1_multiple.jpg
Yup. IMO, very well written (chapter IV in particular)
Hi Tryphon
For the temperature and pressure ranges into which we are able to survive, air is not a frequency dispercive medium.
Jan is referring to two practical issues:
1. Head movement. Wavelength on air is 1m for 340Hz, 0.1m for 3.4kHz, 0.05 for 6.8kHz, 0.025m for 13.6kHz. A head movement half this distance will bring the ears at the position of opposite phase (“head on the vice”).
2. Multiple sound sources due to reflecting surfaces
George
This is not new information about hearing. It is a characteristic of our hearing mechanism.
Nothing to do with phases and harmonics etc. just sensitivity to polarity re. pos vs neg pressure sensitivity of the ear.
THx-RNMarsh
If it is common knowledge, please forgive my ignorance.
I am just asking for some reference because I have not managed to find any.
George
I am just asking for some reference because I have not managed to find any.
George
George,
For my venues the dispersion in air does pop up. At a hundred meters or so it can be a few milliseconds at my upper frequeny limit. (Hint humidity!)
For computer speech recognition systems at one time absolute phase was important, not sure if is still.
ES
For my venues the dispersion in air does pop up. At a hundred meters or so it can be a few milliseconds at my upper frequeny limit. (Hint humidity!)
For computer speech recognition systems at one time absolute phase was important, not sure if is still.
ES
Thank you Ed for the input but I am surprised.
Water is not considered acoustically dispersive even with ultrasonic testing (where frequency dispersion matters a lot)
George
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