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 Post subject: Hypersonic Effect
PostPosted: December 9th, 2017, 10:23 pm 
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Tom,

You will find this research interesting. Going over my posts from the dawn of SACD in another forum found this.

This research says, we can perceive presence frequencies above 20kHz in music even though we cannot hear simple sine waves about 20kHz.

Abstract:
Quote:
Although it is generally accepted that humans cannot perceive sounds in the frequency range above 20 kHz, the question of whether the existence of such “inaudible” high-frequency components may affect the acoustic perception of audible sounds remains unanswered. In this study, we used noninvasive physiological measurements of brain responses to provide evidence that sounds containing high-frequency components (HFCs) above the audible range significantly affect the brain activity of listeners. We used the gamelan music of Bali, which is extremely rich in HFCs with a nonstationary structure, as a natural sound source, dividing it into two components: an audible low-frequency component (LFC) below 22 kHz and an HFC above 22 kHz. Brain electrical activity and regional cerebral blood flow (rCBF) were measured as markers of neuronal activity while subjects were exposed to sounds with various combinations of LFCs and HFCs. None of the subjects recognized the HFC as sound when it was presented alone. Nevertheless, the power spectra of the alpha frequency range of the spontaneous electroencephalogram (alpha-EEG) recorded from the occipital region increased with statistical significance when the 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). In contrast, compared with the baseline, no enhancement of alpha-EEG was evident when either an HFC or an LFC was presented separately. Positron emission tomography measurements revealed that, when an HFC and an LFC were presented together, the rCBF in the brain stem and the left thalamus increased significantly compared with a sound lacking the HFC above 22 kHz but that was otherwise identical. Simultaneous EEG measurements showed that the power of occipital alpha-EEGs correlated significantly with the rCBF in the left thalamus. 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.”


http://www.physiology.org/doi/full/10.1152/jn.2000.83.6.3548

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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 12:40 pm 
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Joined: January 15th, 2015, 7:19 am
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Location: Baltimore MD
Just because someone wrote it or said it does not make it true


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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 12:43 pm 
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Pelliott321 wrote:
Just because someone wrote it or said it does not make it true


Just because it's on the Internet doesn't make it false either ;)

Roscoe


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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 1:22 pm 
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I have seen other research on hearing directionality that requires 30KHz+ capability that is the outer hairs on the cochlea not the inner hairs.

With the research Meridian did for MQA, where all recordings dynamic range and recording bandwidth are covered by 24bit/192KHz.

Works for me with everything running at 24bit/192KHz from A/D to D/A. One day will even bring the turntable out of mothballs for a try. Just for the stuff never reissued.

YMMV!


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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 2:11 pm 
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I can't say I have ever done this kind of testing but two things that both David Berning and I have done is notice a difference in sound with electronic circuits that have responces to for example 20K and 40K. We have never been able to identify what caused the difference but it may be better performance in the audible range or maybe something else. As far as something being more pleasant where frequencies above 20 K are present I cannot argue because I have not done blind testing. Could be an interesting project. The tweeters in my new eggs are pretty flat to 40K on axis and my ACO Pacific mike is flat to within plus/minus 2 dB from 3 Hz to 40KHz.


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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 2:19 pm 
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I have taken 1/4" tape and analyzed the response and there is audio signal out to 30KHz+. Used a 96KHz sample rate A/D and easily seen with an FFT analysis.

Now with higher sample rate PCM, have even seen reviewers digitize their vinyl collection as well and play it back digitally as a reference. I just use HiRez downloads from master recordings and does extremely well.


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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 6:01 pm 
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HAL wrote:
I have seen other research on hearing directionality that requires 30KHz+ capability that is the outer hairs on the cochlea not the inner hairs.


That sounds like an useless hypothesis to me. No one is claiming we can hear above 20kHz in our present hearing testing methods.

The question is, can we perceive music differently if supersonic frequencies are present. That was a big selling point of SACD technology when it came around 2000 and from my personal experience, yes.

Just add a super tweeter going from 15kHz to 30kHz and hear to the analog tape. I would bet two things:
1. you cannot hear above 15kHz in a listening test conducted at an audiologist's office.
2. you will experience the music differently with super tweeter present.

Micheal Fremer says, the brickwall filter at 20kHz is the cause of redbook evils. Vinyl does not have the brickwall filter.

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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 6:19 pm 
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Cogito wrote:
HAL wrote:
I have seen other research on hearing directionality that requires 30KHz+ capability that is the outer hairs on the cochlea not the inner hairs.


That sounds like an useless hypothesis to me. No one is claiming we can hear above 20kHz in our present hearing testing methods.

The question is, can we perceive music differently if supersonic frequencies are present. That was a big selling point of SACD technology when it came around 2000 and from my personal experience, yes.

Just add a super tweeter going from 15kHz to 30kHz and hear to the analog tape. I would bet two things:
1. you cannot hear above 15kHz in a listening test conducted at an audiologist's office.
2. you will experience the music differently with super tweeter present.

Micheal Fremer says, the brickwall filter at 20kHz is the cause of redbook evils. Vinyl does not have the brickwall filter.


As I have mentioned before you must be cautious about differences just by adding a super tweeter due to possible interactions between the regular tweeter and super tweeter than can fold back into the "normal" high frequency range.

Also the comments about brickwall filters which I think have merit are rather moot nowdays as most DACs automatically oversample to much higher rates, not to add information which they cannot do but rather to eliminate the need for brickwall filters.

Tom


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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 6:45 pm 
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tomp wrote:

As I have mentioned before you must be cautious about differences just by adding a super tweeter due to possible interactions between the regular tweeter and super tweeter than can fold back into the "normal" high frequency range.


We do not know how our auditory system works in real life. Here is another of my post from 2001.

Psychoacoustics is based on very simple and straight forward observations and facts. I have no doubt about the perception of 17-20kHz freqs in "absolute" sense when measured with pure sinewave tones. And ofcourse, we have JNDs too based on again, pure sinewave tones. Then those who would argue, transmission of high frequencies in bones, middle-ear, cochlea excitation etc, to determine if they reach our brain.

There is lot of good science in psychoacoustics, which should be used to understand the human complex ear-brain perspective mechanisms as a whole. Instead, many in the psychoacoustics field adopt the easier the "divide and rule" principle. Unfortunately, these finite divisions have do not give realistic understanding of our hearing perceptions. For example, we can perceive 1/30th of the JND thresholds when subjected to dynamic content which music is. Similarly, most of us cant hear above 15kHz, yet we can immediately perceive the difference between tweeter with FFRs of 15 and 20kHz. Same can be said for ultra-sonic frequencies, based upon my readings and intereaction with credible sources.


Quote:
Also the comments about brickwall filters which I think have merit are rather moot nowdays as most DACs automatically oversample to much higher rates, not to add information which they cannot do but rather to eliminate the need for brickwall filters.


Tom, the brickwall filter is applied in the CD source material. No amount of upsampling during playback can change it.

Nyquist theorem states a minimum of twice the max frequency is needed to accurately represent the waveform. Redbook has the max frequency of 44.1kHz, which means it can represent max of 22.05kHz. No material can exist about 22.05kHz on CDs, aka brickwall.

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 Post subject: Re: Hypersonic Effect
PostPosted: December 10th, 2017, 6:50 pm 
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Posts: 606
tomp wrote:

As I have mentioned before you must be cautious about differences just by adding a super tweeter due to possible interactions between the regular tweeter and super tweeter than can fold back into the "normal" high frequency range.


We do not know how our auditory system works in real life. Here is another of my post from 2001.

Psychoacoustics is based on very simple and straight forward observations and facts. I have no doubt about the perception of 17-20kHz freqs in "absolute" sense when measured with pure sinewave tones. And ofcourse, we have JNDs too based on again, pure sinewave tones. Then those who would argue, transmission of high frequencies in bones, middle-ear, cochlea excitation etc, to determine if they reach our brain.

There is lot of good science in psychoacoustics, which should be used to understand the human complex ear-brain perspective mechanisms as a whole. Instead, many in the psychoacoustics field adopt the easier the "divide and rule" principle. Unfortunately, these finite divisions have do not give realistic understanding of our hearing perceptions. For example, we can perceive 1/30th of the JND thresholds when subjected to dynamic content which music is. Similarly, most of us cant hear above 15kHz, yet we can immediately perceive the difference between tweeter with FFRs of 15 and 20kHz. Same can be said for ultra-sonic frequencies, based upon my readings and intereaction with credible sources.


Quote:
Also the comments about brickwall filters which I think have merit are rather moot nowdays as most DACs automatically oversample to much higher rates, not to add information which they cannot do but rather to eliminate the need for brickwall filters.


Tom, the brickwall filter is applied in the CD source material. No amount of upsampling during playback can change it.

Nyquist theorem states a minimum of twice the max frequency is needed to accurately represent the waveform. Redbook has the max frequency of 44.1kHz, which means it can represent max of 22.05kHz. Amy material above 22.05kHz in redbook standard becomes noise, hence the brickwall.

Upsampling reduces the noise levels by raising the dB level of the source material, each bit represents 6dB, it does nothing to the fidelity.

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