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high-end frequencies 10-20k hz

post #1 of 16
Thread Starter 

Why do earphones/headphones enter into the range of 15-20k hz?

 

 

I've talked with a guy that makes trance, and he says typically at most, the frequency doesn't get past 12,000, at even the highest of highs. So if that's true, are there really any types of music, or any games for that matter, where it's actually utilizing frequencies above 18k?

 

 

Or is it all just for show and never really used anyway, unless it's for some very specific thing where people are actually trying to test sounds that are above 18k?

post #2 of 16
Look at the freq. specs these manufacturers use. 10-65k. Its marketing psycho fluff.
post #3 of 16
Thread Starter 
Quote:
Originally Posted by Happy Camper View Post

Look at the freq. specs these manufacturers use. 10-65k. Its marketing psycho fluff.

I get that they might do that to just throw big numbers out there and everything.

 

But disregarding that, are there even really in sounds in relation to music/gaming that even go above 18k, or even 15k for that matter?

 

I know the human ear generally can't even hear above 20k... but if even really varied games only get to 12k, and even really varied music gets to 12-14k, whats the sense adding that additional 6-8k for range with headphones/earphones? ... If the only time you'd even use/hear those frequencies was if you specifically tested for them?

post #4 of 16

This will probably help:
 

http://www.independentrecording.net/irn/resources/freqchart/main_display.htm

 

At the upper end, it's mostly harmonics rather than fundamentals.  Ability to hear will vary from person to person.  At normal sound volume I'm struggling at much more than 15-16 kHz (probably normal for my age).

 

Cymbals are one instrument you will hear above 12k.

post #5 of 16
Thread Starter 
Quote:
Originally Posted by Brooko View Post
 

This will probably help:
 

http://www.independentrecording.net/irn/resources/freqchart/main_display.htm

 

At the upper end, it's mostly harmonics rather than fundamentals.  Ability to hear will vary from person to person.  At normal sound volume I'm struggling at much more than 15-16 kHz (probably normal for my age).

 

Cymbals are one instrument you will hear above 12k.

 

Thanks.

post #6 of 16
There is definitely sound above 12 kHz with some instruments, but mostly ambient cues are found that high.


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post #7 of 16
Quote:
Originally Posted by Happy Camper View Post

Look at the freq. specs these manufacturers use. 10-65k. Its marketing psycho fluff.

 

If they're marketing anything above 20kHz it's for dog tortures, don't buy anything from those brands.

post #8 of 16
Quote:
Originally Posted by TwoEars View Post

If they're marketing anything above 20kHz it's for dog tortures, don't buy anything from those brands.
By your guidelines, there isn't a set out there to buy.
post #9 of 16

If your software player/portable device/home stereo has a graphic EQ try playing with the rightmost slider (usually 16khz) to get a better sense of how those frequencies impact the listening experience.

post #10 of 16

Before to start speculations about idea that high frequencies are or not are  'snake oil' level of things...

Unfortunately CD audio frequency standard (up to 20kHz) was created before 1980, on the basis of comparative tests of 'short listening sessions (every audio sample was auditioned no more than few minutes or less)', now it is recognized, that 'prolonged hearing' tests give other comparative results, especially in audio HF region.

It is generally accepted that 'humans ear' cannot hear/perceive air vibrations in the frequency range above 20 kHz, but new 'controlled lab level' tests it is proved that there is significant increase in the regional cerebral blood flow (rCBF) in the brain, when heared complex audio contain 20kHz to 22 kHz (or even higher) audio components... so increase of blood flow is surely influencing some processes in listeners brain... so it alters the 'mind' anyway. Another question is, is every listener somehow 'feeling' this difference in brains blood flow or is aware of 'changing subtle processes' in his mind... Other researche show, that power spectra of the alpha frequency range of the spontaneous electroencephalogram (alpha-EEG) recorded from the occipital region, when subjects were exposed to sound containing both an HFC and an LFC, compared with an otherwise identical sound from which the HFC was removed (i.e., LFC alone).

Psychological evaluation indicated that the subjects felt the sound containing an HFC to be more pleasant than the same sound lacking an HFC. These results suggest the existence of a previously unrecognized response to complex sound containing particular types of high frequencies above the audible range. We term this phenomenon the “hypersonic effect.”

 

details
http://jn.physiology.org/content/83/6/3548
http://www.icad.org/Proceedings/2002/YagiNishina2002.pdf

 

about HF harmonics
http://www.cco.caltech.edu/~boyk/spectra/spectra.htm

 

wider overview about music and human ear
http://www.silcom.com/~aludwig/EARS.htm

post #11 of 16
Quote:
Originally Posted by dharma View Post
 

Before to start speculations about idea that high frequencies are or not are  'snake oil' level of things...

Unfortunately CD audio frequency standard (up to 20kHz) was created before 1980, on the basis of comparative tests of 'short listening sessions (every audio sample was auditioned no more than few minutes or less)', now it is recognized, that 'prolonged hearing' tests give other comparative results, especially in audio HF region.

It is generally accepted that 'humans ear' cannot hear/perceive air vibrations in the frequency range above 20 kHz, but new 'controlled lab level' tests it is proved that there is significant increase in the regional cerebral blood flow (rCBF) in the brain, when heared complex audio contain 20kHz to 22 kHz (or even higher) audio components... so increase of blood flow is surely influencing some processes in listeners brain... so it alters the 'mind' anyway. Another question is, is every listener somehow 'feeling' this difference in brains blood flow or is aware of 'changing subtle processes' in his mind... Other researche show, that power spectra of the alpha frequency range of the spontaneous electroencephalogram (alpha-EEG) recorded from the occipital region, when subjects were exposed to sound containing both an HFC and an LFC, compared with an otherwise identical sound from which the HFC was removed (i.e., LFC alone).

Psychological evaluation indicated that the subjects felt the sound containing an HFC to be more pleasant than the same sound lacking an HFC. These results suggest the existence of a previously unrecognized response to complex sound containing particular types of high frequencies above the audible range. We term this phenomenon the “hypersonic effect.”

 

details
http://jn.physiology.org/content/83/6/3548
http://www.icad.org/Proceedings/2002/YagiNishina2002.pdf

 

about HF harmonics
http://www.cco.caltech.edu/~boyk/spectra/spectra.htm

 

wider overview about music and human ear
http://www.silcom.com/~aludwig/EARS.htm

 

A couple of weeks ago I took some time to write up a criticism of this study on a website whose mention is verboten here on head-fi, so here's a copy:

 

In response to the oft-cited Oohashi high frequency study - http://jn.physiology.org/content/83/6/3548

First, Oohashi is an odd and brilliant man, an artist and a scientist. Here's an interview which gives you a gist of why he does what he does - http://www.sidianersatzvanes.com/supplemental/dr-tsutomu-oohashi/

To him the pursuit of what he calls the "hypersonic effect" is something of a lifelong endeavor. His hypothesis is deeply rooted in decades of experience in the music business and research in biology. Finding evidence to substantiate his ideas on human hearing is deeply important to him. When, in the late 90s, Japanese researchers attempted to substantiate claims of the superior audio quality of high sampling rates and high bandwidth recordings (96khz & DSD) in preparation for the arrival of new commercial formats (SACD, DVD-A, etc.), enthusiasm sometimes overrode practical sense. Improvements were quantified by soliciting listening reports in the form of questionnaires, as opposed to objective observation of perception.

 

That's not to say that such research was unfounded. One of the major revolutions in engineering was brought about by Floyd Toole's questionnaire-based research from the 1970s at NRC. Without those subjective reports we would not have a firm grasp of what metrics of speaker design actually matter to listeners.

 

But Oohashi, in true researcher fashion, did not buy the hypothetical explanations and positive results of those late 90s studies. Being a neuroscientist he wanted to apply techniques from medical diagnostics - namely brain imaging. It's important to remember that to the 70-something Oohashi of the late 90s these techniques were still very new, unavailable at the time of his doctoral research from decades back. Enter the hypersonic study.

The study was laboriously designed to include real live music with ultrasonic content at high sampling rates and with high bandwidth transducers. Recordings were made by lab mics and converted to digital @ 1.92mhz single bit delta-sigma modulation. Not being an idiot Oohashi was of course aware of the possibility of intermodulation distortion messing up his results.

 

In simple terms, intermodulation distortion is composed of non-harmonic products of interference between two or more frequencies. Say you measure 18 & 19khz tones, there you're looking for the level of the 1khz tone that is the difference of the frequencies. However in real life IMD is even more complex than that because we are dealing with complex non-linear systems. Even with the 18 & 19khz test tones you will get a pattern of tones on both immediate sides of the respective frequencies as well as all sorts of other hash. And this is simply on the electronic end of things! Transducers are even worse, the distortion products of musical signals may add up to be a degree of magnitude larger than that of single test tones. Yes, that speaker with .3% THD @ 1khz could still produce 3% or more total distortion with complex material, just from electromechanical limitations.

 

In order to minimize the possibility of IMD on the digital side of things Oohashi and crew split the signals into LFC (low-frequency content, under 22khz) and HFC (high frequency content) by using very steep high-order digital filters. Both signals were then rooted to separate amplifiers and separate transducers. The amplifiers were by Accuphase, some of the best that you can get. The LFC content was reproduced by a horn tweeter and two woofers and HFC content was reproduced by a diamond dome tweeter. Diamond domes have a high breakup frequency, typically 40+ khz, but up there when they ring they truly ring, 10-20+ db.

 

Anyway, the test protocol was simple and straightforward. There were four conditions: LFC content only, HFC content only, LFC+HFC content and silence for a baseline measurement. The first measurement tool borrowed from medical diagnostics was an alpha wave electroencephalograph, the thing where they stick a bunch of electrodes all around the skull and measure changes in electric potential. It is by necessity a very broad measurement, indicative of massive neuronal activity but indiscriminate in terms of specifics. High levels of alpha waves occur during meditation and when alpha waves intrude on sleep it is typically during REM cycles, vivid wakeful-like states. They indicate a kind of active idleness, when a person is frantically thinking you tend to have a decrease in alpha wave activity. This activity can also be willfully regulated by a person through neurofeedback training or meditation. What does it mean? Well...

The results indicated LFC and HFC signals individually offered only minute, insignificant changes in alpha activity, but that LFC+HFC signals showed a notable increase. This is the red flag: if ultrasonic components of musical signals can be interpreted to have an effect by boosting alpha potential then why do they do so only in the presence of regular 20-20,000hz signals?

 

The second measurement tool was positron emission tomography, a state-of-the-art three dimensional imaging system of cell metabolism. The results showed markedly decreased metabolic brain activity with HFC signals when compared with LFC and baseline signals and, again, markedly increased metabolic activity with LFC+HFC signals. Ultrasonic components this time are shown to not have much of an effect unless they are combined with LFC.

Oohashi concluded that only the combination of the two signals produced the hypersonic effect, moreover that the combination of the two signals was responsible for [i]novel[/i] brain activity outside of the areas normally associated with auditory processing.

 

Here's the rub, though: previous research has shown that people will in fact react differently to music once a certain level of distortion is introduced. Moreover, if these are experienced listeners primed for critical listening, they are likely to become actively annoyed at the presence of unnatural distortion. Oohashi's setup was inadequate to prevent the likelyhood of added distortion, whether through unstated digital filtering methods, or transducer limitations, or even the physical positioning of the speakers (high frequency wavelengths are so small by themselves and in comparison to a regular dome tweeter that moving your head even a centimeter can have an effect).

 

Now these concerns could've and would've been allayed if Oohashi's results were repeatable. Independent teams have failed to reproduce both the detection of ultrasonic frequencies by the ear and brain. They've also discounted the purported synergistic properties of adding ultrasonic content to regular recordings, since subjects simply couldn't tell the difference (Oohashi claimed that LFC+HFC reports indicated increased enjoyment).

 

The tough thing is that without being familiar with the details of Oohashi's setup or with prior brain imaging studies, it is difficult to draw any sort of definitive conclusion from his study. But being skeptical one can say that his study has flaws, that it has proven non-reproducible and that there is a sizable amount of contrary evidence.

post #12 of 16
Quote:
Originally Posted by aionis View Post
 

Why do earphones/headphones enter into the range of 15-20k hz?

 

 

I've talked with a guy that makes trance, and he says typically at most, the frequency doesn't get past 12,000, at even the highest of highs. So if that's true, are there really any types of music, or any games for that matter, where it's actually utilizing frequencies above 18k?

 

 

Or is it all just for show and never really used anyway, unless it's for some very specific thing where people are actually trying to test sounds that are above 18k?

 

No, it is not show. There are a number of reasons why high frequencies do matter. There is an article in German language which explains it very well. http://www.aktives-hoeren.de/downloads/Grenzen_der_DT_Rohfassung300708.pdf

I can't translate it but if you take a look at the two graphs on page 6 of the article you'll notice that the frequencies of a typical classical piece of music easily reach into 40 or 50 kHz. Of course, one cannot "hear" a sound above 20 kHz. That doesn't mean it's irrelevant. Apparently, the brain needs the whole frequency spectum to determine a sound and for the orientation. Figure 6 at page 10 shows that downsampling leads to a broadening of the sound on the time axis. The sound gets "stretched" into time and lasts longer. Our hearing orientation is somehow influenced by this effect. That's one of the reasons why it is impossible to reproduce a "natural" sound experience with a CD recording regardless of how well the CD is made. If you take a look at the last 3 diagrams on page 20 of the article you'll get an impression of what happens when a song is put onto a CD. The first graph shows the frequency range of an LP recording, the second the a digitalized recording with 192 kHz sampling rate, and the third one a CD recording.

post #13 of 16
Quote:
Originally Posted by Rafu64 View Post
 

 

No, it is not show. There are a number of reasons why high frequencies do matter. There is an article in German language which explains it very well. http://www.aktives-hoeren.de/downloads/Grenzen_der_DT_Rohfassung300708.pdf

I can't translate it but if you take a look at the two graphs on page 6 of the article you'll notice that the frequencies of a typical classical piece of music easily reach into 40 or 50 kHz. Of course, one cannot "hear" a sound above 20 kHz. That doesn't mean it's irrelevant. Apparently, the brain needs the whole frequency spectum to determine a sound and for the orientation.

 

The brain has no way of telling anything past 20khz since this information is not communicated to the nerves. The localization of a sound is determined by interaural delay, that is the comparison between signals received by the left and the right ear. There are also cues in the frequency response of the head related transform, but these do not go beyond 20khz.

 

Quote:
Originally Posted by Rafu64 View Post
 Figure 6 at page 10 shows that downsampling leads to a broadening of the sound on the time axis. The sound gets "stretched" into time and lasts longer. Our hearing orientation is somehow influenced by this effect.

 

No, that is an artifact introduced by the specific filter used. These figures are borrowed from an AES paper by Mike Story of DCS who is actively promoting a "need" for his products by arbitrarily choosing filters, filter slopes and graphing pre- and post- ringing to make it seem like 192khz is the best. Change the filter and the "broadening" of the response in the time domain changes as well, in fact you can get a perfect up/down graph using 44.1khz.

 

Quote:
Originally Posted by Rafu64 View Post
The first graph shows the frequency range of an LP recording, the second the a digitalized recording with 192 kHz sampling rate, and the third one a CD recording.

 

Yes, and if you extend it to any arbitrary frequency - 352khz, 1mhz, 1ghz, and so on you can capture even more inaudible noise.

post #14 of 16
Quote:
Originally Posted by anetode View Post
 

 

The brain has no way of telling anything past 20khz since this information is not communicated to the nerves. The localization of a sound is determined by interaural delay, that is the comparison between signals received by the left and the right ear. There are also cues in the frequency response of the head related transform, but these do not go beyond 20khz.

 

 

How can you exclude that there might be another way for the brain of receiving this information? We know of the effects UV-light has although we're unable to see it. Anyway, I don't want to speculate. I am not a neuro-scientist and cannot seriously debate these questions. But, I have listened to a ton of CD-music (pop/rock) and, in most cases, it sounded worse and somehow flattened out compared to Hi-res tracks. There are few exceptions, though, but for me it is enough for not buying CDs anymore when I can get a high-resolution recording.
 

post #15 of 16
Quote:
Originally Posted by Rafu64 View Post
 

How can you exclude that there might be another way for the brain of receiving this information?

Basic knowledge of anatomy and acoustics. If there is evidence to the contrary then I'm eager to learn about it. So far I haven't found anything convincing.

 

As for what you prefer - great, whatever makes you happy :)

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