a_recording
Member of the Trade: Lachlanlikesathing
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Hi guys! This is probably going to be an obscure topic and a very long opening post, but I was interested in what you guys would make of this.
I recently bought the Akira Blu-Ray, which among other things comes with a huge booklet with articles explaining how the musical director of the movie, one Tsutomu Oohashi, approached the audio for this new Blu-Ray release - which has a 192kHz sampling rate, 24bit Lossless TrueHD track. Besides being a composer, Oohashi is also a neuroscientist(!), and in his research he claimed to have discovered a phenomenon he called the 'Hypersonic Effect'.
In a nutshell, the Hypersonic Effect is the claim that, although human hearing tops out at around 22kHz for high frequencies, frequencies as high as 100kHz have the psycho-acoustic effect of making the listener respond better to the sound, as well as lead to a measurably increased level of brain activity demonstrated in EEG results. I won't pretend to understand the actual science of it
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, but supposedly Oohashi set up double blind tests to verify this effect. You can read about it here: Hypersonic effect - Wikipedia, the free encyclopedia The wiki article has a link to Oohashi's original paper in the references, as well as a refutation of the theory (though because the effect is supposedly subconscious I'm not sure an ABX test to ask listeners to actively identify the better audio is appropriate.)
Ever since reading about this effect, I've been fairly curious about whether it holds any truth at all. Of course, for the effect to be experienced, everything along the chain has to be able to reproduce frequencies over 22kHz. The booklet argues for a new audio standard for equipment rated to have a frequency response up to 100kHz. It's possible to buy super-tweeters for loud speakers, such as the Tannoy ST-50, that reproduce up to 100kHz.
In the portable and IEM world though, I wonder how this theory holds up? To me, IEM's seem like an ideal way to reproduce super high frequency sounds - tiny, extremely sensitive drivers. However, most portables have frequency responses that terminate at 20kHz, even lossless rips from CDs will only have the maximum frequency of 22kHz, and most IEM's are rated at a frequency response of 22kHz. I think that in the case of some manufacturers, like Head-Direct and their RE0's, they may actually not have the resources to even test for frequencies higher than human hearing - again, I won't pretend to know what equipment is necessary, but I'd imagine some combination of a controlled acoustic chamber, hyper sensitive microphones, and who knows what.
To be honest though, I suspect these manufacturer frequency responses are arbitrary - its commonly accepted that you can't hear anything above 20kHz, so manufacturers normally wouldn't be inclined to test for much beyond that, and of course, maybe avoid looking foolish by printing insane frequency responses.
So, at the end of this long post, my question is, do you guys think this holds any water in your experience? For instance, the RE0's are extremely popular here in large part for their extended treble response - could their popularity be in part because their treble goes high enough to induce a positive psycho-acoustic response?
Could an IEM driver add high frequency sounds even when they aren't present in the source (either in the file or the player) as a form of 'coloration'? Can you guys think of any other IEMs that might have higher frequency responses - for instance the Sony EX700 is rated for 28kHz. (Though no amount Hypersonic effect actually made me like them when I had them in my possession for a while.)
Should they add a fourth balanced armature to high end IEMs to reproduce frequencies no one can actually hear?
Oh the possibilities.
I recently bought the Akira Blu-Ray, which among other things comes with a huge booklet with articles explaining how the musical director of the movie, one Tsutomu Oohashi, approached the audio for this new Blu-Ray release - which has a 192kHz sampling rate, 24bit Lossless TrueHD track. Besides being a composer, Oohashi is also a neuroscientist(!), and in his research he claimed to have discovered a phenomenon he called the 'Hypersonic Effect'.
In a nutshell, the Hypersonic Effect is the claim that, although human hearing tops out at around 22kHz for high frequencies, frequencies as high as 100kHz have the psycho-acoustic effect of making the listener respond better to the sound, as well as lead to a measurably increased level of brain activity demonstrated in EEG results. I won't pretend to understand the actual science of it
Ever since reading about this effect, I've been fairly curious about whether it holds any truth at all. Of course, for the effect to be experienced, everything along the chain has to be able to reproduce frequencies over 22kHz. The booklet argues for a new audio standard for equipment rated to have a frequency response up to 100kHz. It's possible to buy super-tweeters for loud speakers, such as the Tannoy ST-50, that reproduce up to 100kHz.
In the portable and IEM world though, I wonder how this theory holds up? To me, IEM's seem like an ideal way to reproduce super high frequency sounds - tiny, extremely sensitive drivers. However, most portables have frequency responses that terminate at 20kHz, even lossless rips from CDs will only have the maximum frequency of 22kHz, and most IEM's are rated at a frequency response of 22kHz. I think that in the case of some manufacturers, like Head-Direct and their RE0's, they may actually not have the resources to even test for frequencies higher than human hearing - again, I won't pretend to know what equipment is necessary, but I'd imagine some combination of a controlled acoustic chamber, hyper sensitive microphones, and who knows what.
To be honest though, I suspect these manufacturer frequency responses are arbitrary - its commonly accepted that you can't hear anything above 20kHz, so manufacturers normally wouldn't be inclined to test for much beyond that, and of course, maybe avoid looking foolish by printing insane frequency responses.
So, at the end of this long post, my question is, do you guys think this holds any water in your experience? For instance, the RE0's are extremely popular here in large part for their extended treble response - could their popularity be in part because their treble goes high enough to induce a positive psycho-acoustic response?
Could an IEM driver add high frequency sounds even when they aren't present in the source (either in the file or the player) as a form of 'coloration'? Can you guys think of any other IEMs that might have higher frequency responses - for instance the Sony EX700 is rated for 28kHz. (Though no amount Hypersonic effect actually made me like them when I had them in my possession for a while.)
Should they add a fourth balanced armature to high end IEMs to reproduce frequencies no one can actually hear?
Oh the possibilities.
