9 ms·

Ear Speakers – Research, Design, and Evolution

96 points by mxfh 7y ago

robocat 7y ago
I live articles that show the process of designing completely new hardware. I do wonder if this article is missing any dead ends; only showing the iterative improvements?
dsr_ 7y ago
I wonder if the F/R graph has been pre-corrected against human perception? It looks really flat -- and you'd ordinarily think that was good, but it turns out that humans don't have equally sensitive hearing at all frequencies. There are a range of curves from different studies, and most musical transducers pick one of those curves and try to emulate it in hardware, so that a smooth frequency sweep from low to high continues to sound equally loud. Perhaps Valve is planning on adding that through digital equalization.
- atoav 7y ago
  It is worse than that, the curve of human hearing is not only everything else than flat, it also changes with volume.
  - skavi 7y ago
    Lots of newer devices compensate for that. The HomePod and QC35 for example.
    - deleted 7y ago
      [deleted]
  - JohnBooty 7y ago
    One thing to note is that it's not all doom and gloom. Unless aiming for a full VR positional audio experience like Valve is doing here, an audio playback system (headphones, speakers, etc) doesn't have to compensate for all of the various nuances of human hearing. After all, sounds "in real life" don't do that. All an audio playback system needs to do is reproduce the original sound accurately, perhaps with some Fletcher-Munson compensation to enhance bass at low listening volumes. (Interestingly, this sort of feature was present on home stereos for several decades. The poorly-named "loudness" knob increased bass so you could enjoy satisfying bass without increasing the overall system volume...)
    - KozmoNau7 7y ago
      The loudness button's functionality lives on, in an improved form. Any reasonably modern AV receiver with Audyssey or equivalent room correction/DSP will apply dynamic EQ based on the volume setting, to compensate for volume-dependent frequency sensitivity. It's a great way to get speakers to sound "bigger" than they are, at volume settings.
      - JohnBooty 7y ago
        Audyssey is absolutely wonderful. It makes a dramatic difference and is light years ahead of a simple loudness knob. However, I have to wonder - for those with Audyssey-equipped receivers, what % of owners bother to complete the setup process with the calibration microphone? I suspect that number is unfortunately low. :-/ Also, I don't think too many people listen to music on AV receivers these days. The product category itself seems to be fading. Home theaters have swung toward soundbars, and music is listened to on computers, mobile devices, and/or Bluetooth speakers. I'm saying this as a pretty old-school stalwart myself, with a fairly capable AV receiver in the living room for video and a bunch of audiophile-ish two channel gear for music.
        KozmoNau7 7y ago
        I don't think the AV receiver is going away anytime soon. Just like what has happened to stereo amplifiers, what is happening is that the opportunistisk low end of the market is moving on. Cheap radios, turntables and amplifiers were replaced with cheap plastic mini/micro stereos, which were in turn replaced by all-in-ones, which were replaced by bluetooth speakers, and so on. Cheap AV receivers and especially cheap home-theater-in-a-box type products have been replaced by sound bars, which I would say is actually an improvement in a lot of cases. Some of the low-end AV receivers that were on the market in the 90s and 2000s were unmitigated garbage and a waste of money. Quality fifi separates live on, and you can still buy mini/micro stereos and all-in-one radio/media player devices. You can still buy AV receivers, but the worst cheap ones have disappeared. I'm not sure you can actually buy HTIB junk anymore, but good riddance to that rubbish. The appreciation for good sound lives on, but the more complicated devices move to more of a niche role, sticking around for those of us who desire really good sound, and don't mind a bit of a complicated setup process. For everyone else, a sound bar with a wireless subwoofer gets them most of the way, with significantly less effort. Listening on a computer is simply the next replacement for turntables, tape decks, CD players, DVD/Bluray players, standalone streaming devices and so on. My primary media source is an ultra small form factor PC streaming FLAC and DVD/BR rips from my NAS, hooked up to my receiver over HDMI. It's almost too easy to get amazing sound quality today. Similarly a smartphone will produce great sound quality with decent source material. The playback device has become a footnote, they're all capable of great sound quality today, as long as you pipe it to something higher quality than a cheap soundbar/bluetooth speaker.
- jasonwatkinspdx 7y ago
  These folks are rather clearly a lot more sophisticated than "What's a Fletcher Munson Curve?" In all likelihood they've had to tune things to a very fine degree, both in dsp and in the physical driver design. Because these are used in the near field, with the specific intent of leveraging acoustic cues from the outer ear, they won't be able to just reuse a reference curve developed for headphones or speakers. They have a dummy head for binaural measurements, so this isn't a particular hard thing for them to calibrate.
  - falcolas 7y ago
    > These folks are rather clearly a lot more sophisticated than "What's a Fletcher Munson Curve?" And yet they're reinventing open headphones and calling it revolutionary? Only a little sarcastic.
    - boardwaalk 7y ago
      If open-back headphones are not closed-back headphones, these off-ear headphones are not open-backed headphones — there seems to be as much differentiation to me. And they didn’t say “revolutionary” or similar anywhere, as far as I can see.
      - chupasaurus 7y ago
        For "off-ear" headphones there are only 3 different ways to build them: closed, open or half-open, solely based on amount of air flow given to a driver (and the type of driver doesn't matter).
      - falcolas 7y ago
        You're, if I can be frank, wrong. The difference between the two different types of headphones is the amount of isolation the headphones provide. Open back headphones provide minimal, if any, isolation. Closed back provide significant sound isolation. This difference was outlined by a sibling comment which was sadly downvoted. These are simply open backed headphones that use a different method of setting the distance between the driver and the ear. That's all.
- p1necone 7y ago
  The world around you doesn't adjust it's volume to match human hearing sensitivity at different frequencies - so why would you want to do that when trying to achieve VR immersion?
wallflower 7y ago
If you are interested in software-driven headphones, the Smyth Realiser series has always fascinated me. https://smyth-research.com/ https://smyth-research.com/ https://www.cnet.com/news/smyth-realiser-a8-perfect-surround-sound-over-headphones/ https://www.cnet.com/news/smyth-realiser-a8-perfect-surround... https://www.soundonsound.com/reviews/smyth-research-realiser-a8 https://www.soundonsound.com/reviews/smyth-research-realiser...
- bonestamp2 7y ago
  These things are awesome! They used to ship the A8 with STAX Ear Speakers... which when I discovered it almost 10 years ago was the first time I had ever heard the term "ear speakers" or had ever heard of electrostatic headphones, or the brand STAX (from Japan). All in all, The Realiser and the STAX were unbelievable! I got bored of the A8 after awhile but I never got bored of the STAX... I wish electrostatic headphones were more widely available in general, they're a true gem. Everyone that hears them is in awe.
  - Azrael3000 7y ago
    And they are "easy" to build yourself. I wrote a guide about doing so here [0] which is based on this enormous head-fi thread [1]. 0: https://github.com/Azrael3000/headphone-guide https://github.com/Azrael3000/headphone-guide 1: https://www.head-fi.org/threads/my-diy-electrostatic-headphones.498292/ https://www.head-fi.org/threads/my-diy-electrostatic-headpho...
    - wallflower 7y ago
      Wow, very impressive to DIY! It is one thing to do speakers DIY, quite another to make headphones, let alone e-stats. For those who are interested in entry-level, non-DIY route Drop (formerly Massdrop) has their variant of the classic Koss ESP/950 electrostatic headphones for around $500. They sold out earlier this year. https://drop.com/buy/massdrop-x-koss-esp-95x-electrostatic-system?mode=guest_open https://drop.com/buy/massdrop-x-koss-esp-95x-electrostatic-s...
chrischen 7y ago
Elephant in the room is that it still has a wire sticking out.
- GuB-42 7y ago
  That's not the subject. But do you really think they didn't even consider wireless? Turns out it is really hard. You need a low latency, reliable ~10Gbps link. You also need the battery to be power all the that stuff. Putting everything inside the headset would be ideal but you also have to consider that weight affects comfort and immersion significantly. The first semi successful attempt is TPCast but it is far from perfect. I don't know much about the Vive wireless but it seems to work better but still have its own set of issues. Both are also rather expensive (~$300). So for now, we seem to be stuck with fully integrated low end or wired high end. I think we still need to wait a bit more for wireless high end.
  - chrischen 7y ago
    I've been using a Vive with the official wireless adapter and it works flawlessly. The subject is immersion. My point is that with all that goes into making the audio immersive, the wire out back instantly defeats any gains there.
voldacar 7y ago
These look really interesting! I own an original AKG K1000 from 1989 and they definitely have a better sense of "solidity" and "presence" than ordinary headphones with drivers that seal against your head, due to the natural crossfeed. Other than the K1000 successor that got released a year or two ago (mysphere 3) there has been very little development since then in the field of open-air driver headphones. Hopefully these can sound good without breaking the bank! Also this is the first headphone that uses a driver based on the BMR principle that I am aware of
- falcolas 7y ago
  HiFiMan has a series of open air planar magnetic drivers, and they're absolutely awesome to listen to. I've yet to find other headphones that can stack up. Their only downside is the weight.
  - voldacar 7y ago
    Which Hifimans are you referring to? Just to clarify, I'm talking not about open-back headphones, but headphones that don't have pads and consequently don't form a seal between the ear and the driver.
    - falcolas 7y ago
      There is no seal. A seal implies a lack of air movement and sound isolation associated with closed back headphones. Open back headphones have no sound isolation in or out. The parts that contact around your ears with HiFiMan's simply set the distance from the driver to your ear, in a comfortable way.
      - voldacar 7y ago
        That is incorrect. When I say "seal", I am referring to the sealed cavity between ear and driver, not to anything behind the driver. This is actually quite important for planars in particular, as a broken seal between the ear and driver leads to rapid bass rolloff, due to the lack of excursion found in most planar drivers (ime this is most noticeable with audezes since their excursion is especially low but I notice it with my HE-6 when I don't have the pads on my head quite right and there's a tiny gap between my head and the pads somewhere)
neves 7y ago
Looks like it will be impossible to play with someone else in the same room, right?
- rodgerd 7y ago
  Sure but you're already flailing around with a vision-blocking helmet, waving your hands. Noise pollution seems like less of a hazard for a bystander than getting whacked by the player.
cryptonector 7y ago
Oh, wow, this really is cool.
dmix 7y ago
> Humans in general are very sensitive to sounds within 2kHZ-5kHz range. If the frequency of a virtual sound doesn’t match up to what we expect it to be in reality, then we are more likely to identify the sound as “not real”. This is particularly true if you compare how easy it is to tell if someone’s voice is broadcast through a speaker vs. someone is talking beside you. I never thought about that in regards to gaming or even conference room voice chat, it is extremely easy to tell the difference. Must be a challenging problem set to solve, sounds fun!
tictoc 7y ago
How does sound affect us between receiving via headphones vs a speaker?

96 points by mxfh 7y ago

I live articles that show the process of designing completely new hardware. I do wonder if this article is missing any dead ends; only showing the iterative improvements?

dsr_ 7y ago

I wonder if the F/R graph has been pre-corrected against human perception? It looks really flat -- and you'd ordinarily think that was good, but it turns out that humans don't have equally sensitive hearing at all frequencies. There are a range of curves from different studies, and most musical transducers pick one of those curves and try to emulate it in hardware, so that a smooth frequency sweep from low to high continues to sound equally loud. Perhaps Valve is planning on adding that through digital equalization.

atoav 7y ago
It is worse than that, the curve of human hearing is not only everything else than flat, it also changes with volume.
- skavi 7y ago
  Lots of newer devices compensate for that. The HomePod and QC35 for example.
  - deleted 7y ago
    [deleted]
- JohnBooty 7y ago
  One thing to note is that it's not all doom and gloom. Unless aiming for a full VR positional audio experience like Valve is doing here, an audio playback system (headphones, speakers, etc) doesn't have to compensate for all of the various nuances of human hearing. After all, sounds "in real life" don't do that. All an audio playback system needs to do is reproduce the original sound accurately, perhaps with some Fletcher-Munson compensation to enhance bass at low listening volumes. (Interestingly, this sort of feature was present on home stereos for several decades. The poorly-named "loudness" knob increased bass so you could enjoy satisfying bass without increasing the overall system volume...)
  - KozmoNau7 7y ago
    The loudness button's functionality lives on, in an improved form. Any reasonably modern AV receiver with Audyssey or equivalent room correction/DSP will apply dynamic EQ based on the volume setting, to compensate for volume-dependent frequency sensitivity. It's a great way to get speakers to sound "bigger" than they are, at volume settings.
    - JohnBooty 7y ago
      Audyssey is absolutely wonderful. It makes a dramatic difference and is light years ahead of a simple loudness knob. However, I have to wonder - for those with Audyssey-equipped receivers, what % of owners bother to complete the setup process with the calibration microphone? I suspect that number is unfortunately low. :-/ Also, I don't think too many people listen to music on AV receivers these days. The product category itself seems to be fading. Home theaters have swung toward soundbars, and music is listened to on computers, mobile devices, and/or Bluetooth speakers. I'm saying this as a pretty old-school stalwart myself, with a fairly capable AV receiver in the living room for video and a bunch of audiophile-ish two channel gear for music.
      - KozmoNau7 7y ago
        I don't think the AV receiver is going away anytime soon. Just like what has happened to stereo amplifiers, what is happening is that the opportunistisk low end of the market is moving on. Cheap radios, turntables and amplifiers were replaced with cheap plastic mini/micro stereos, which were in turn replaced by all-in-ones, which were replaced by bluetooth speakers, and so on. Cheap AV receivers and especially cheap home-theater-in-a-box type products have been replaced by sound bars, which I would say is actually an improvement in a lot of cases. Some of the low-end AV receivers that were on the market in the 90s and 2000s were unmitigated garbage and a waste of money. Quality fifi separates live on, and you can still buy mini/micro stereos and all-in-one radio/media player devices. You can still buy AV receivers, but the worst cheap ones have disappeared. I'm not sure you can actually buy HTIB junk anymore, but good riddance to that rubbish. The appreciation for good sound lives on, but the more complicated devices move to more of a niche role, sticking around for those of us who desire really good sound, and don't mind a bit of a complicated setup process. For everyone else, a sound bar with a wireless subwoofer gets them most of the way, with significantly less effort. Listening on a computer is simply the next replacement for turntables, tape decks, CD players, DVD/Bluray players, standalone streaming devices and so on. My primary media source is an ultra small form factor PC streaming FLAC and DVD/BR rips from my NAS, hooked up to my receiver over HDMI. It's almost too easy to get amazing sound quality today. Similarly a smartphone will produce great sound quality with decent source material. The playback device has become a footnote, they're all capable of great sound quality today, as long as you pipe it to something higher quality than a cheap soundbar/bluetooth speaker.
jasonwatkinspdx 7y ago
These folks are rather clearly a lot more sophisticated than "What's a Fletcher Munson Curve?" In all likelihood they've had to tune things to a very fine degree, both in dsp and in the physical driver design. Because these are used in the near field, with the specific intent of leveraging acoustic cues from the outer ear, they won't be able to just reuse a reference curve developed for headphones or speakers. They have a dummy head for binaural measurements, so this isn't a particular hard thing for them to calibrate.
- falcolas 7y ago
  > These folks are rather clearly a lot more sophisticated than "What's a Fletcher Munson Curve?" And yet they're reinventing open headphones and calling it revolutionary? Only a little sarcastic.
  - boardwaalk 7y ago
    If open-back headphones are not closed-back headphones, these off-ear headphones are not open-backed headphones — there seems to be as much differentiation to me. And they didn’t say “revolutionary” or similar anywhere, as far as I can see.
    - chupasaurus 7y ago
      For "off-ear" headphones there are only 3 different ways to build them: closed, open or half-open, solely based on amount of air flow given to a driver (and the type of driver doesn't matter).
    - falcolas 7y ago
      You're, if I can be frank, wrong. The difference between the two different types of headphones is the amount of isolation the headphones provide. Open back headphones provide minimal, if any, isolation. Closed back provide significant sound isolation. This difference was outlined by a sibling comment which was sadly downvoted. These are simply open backed headphones that use a different method of setting the distance between the driver and the ear. That's all.
p1necone 7y ago
The world around you doesn't adjust it's volume to match human hearing sensitivity at different frequencies - so why would you want to do that when trying to achieve VR immersion?

wallflower 7y ago

If you are interested in software-driven headphones, the Smyth Realiser series has always fascinated me. https://smyth-research.com/ https://smyth-research.com/ https://www.cnet.com/news/smyth-realiser-a8-perfect-surround-sound-over-headphones/ https://www.cnet.com/news/smyth-realiser-a8-perfect-surround... https://www.soundonsound.com/reviews/smyth-research-realiser-a8 https://www.soundonsound.com/reviews/smyth-research-realiser...

bonestamp2 7y ago
These things are awesome! They used to ship the A8 with STAX Ear Speakers... which when I discovered it almost 10 years ago was the first time I had ever heard the term "ear speakers" or had ever heard of electrostatic headphones, or the brand STAX (from Japan). All in all, The Realiser and the STAX were unbelievable! I got bored of the A8 after awhile but I never got bored of the STAX... I wish electrostatic headphones were more widely available in general, they're a true gem. Everyone that hears them is in awe.
- Azrael3000 7y ago
  And they are "easy" to build yourself. I wrote a guide about doing so here [0] which is based on this enormous head-fi thread [1]. 0: https://github.com/Azrael3000/headphone-guide https://github.com/Azrael3000/headphone-guide 1: https://www.head-fi.org/threads/my-diy-electrostatic-headphones.498292/ https://www.head-fi.org/threads/my-diy-electrostatic-headpho...
  - wallflower 7y ago
    Wow, very impressive to DIY! It is one thing to do speakers DIY, quite another to make headphones, let alone e-stats. For those who are interested in entry-level, non-DIY route Drop (formerly Massdrop) has their variant of the classic Koss ESP/950 electrostatic headphones for around $500. They sold out earlier this year. https://drop.com/buy/massdrop-x-koss-esp-95x-electrostatic-system?mode=guest_open https://drop.com/buy/massdrop-x-koss-esp-95x-electrostatic-s...

chrischen 7y ago

Elephant in the room is that it still has a wire sticking out.

GuB-42 7y ago
That's not the subject. But do you really think they didn't even consider wireless? Turns out it is really hard. You need a low latency, reliable ~10Gbps link. You also need the battery to be power all the that stuff. Putting everything inside the headset would be ideal but you also have to consider that weight affects comfort and immersion significantly. The first semi successful attempt is TPCast but it is far from perfect. I don't know much about the Vive wireless but it seems to work better but still have its own set of issues. Both are also rather expensive (~$300). So for now, we seem to be stuck with fully integrated low end or wired high end. I think we still need to wait a bit more for wireless high end.
- chrischen 7y ago
  I've been using a Vive with the official wireless adapter and it works flawlessly. The subject is immersion. My point is that with all that goes into making the audio immersive, the wire out back instantly defeats any gains there.

voldacar 7y ago

These look really interesting! I own an original AKG K1000 from 1989 and they definitely have a better sense of "solidity" and "presence" than ordinary headphones with drivers that seal against your head, due to the natural crossfeed. Other than the K1000 successor that got released a year or two ago (mysphere 3) there has been very little development since then in the field of open-air driver headphones. Hopefully these can sound good without breaking the bank! Also this is the first headphone that uses a driver based on the BMR principle that I am aware of

falcolas 7y ago
HiFiMan has a series of open air planar magnetic drivers, and they're absolutely awesome to listen to. I've yet to find other headphones that can stack up. Their only downside is the weight.
- voldacar 7y ago
  Which Hifimans are you referring to? Just to clarify, I'm talking not about open-back headphones, but headphones that don't have pads and consequently don't form a seal between the ear and the driver.
  - falcolas 7y ago
    There is no seal. A seal implies a lack of air movement and sound isolation associated with closed back headphones. Open back headphones have no sound isolation in or out. The parts that contact around your ears with HiFiMan's simply set the distance from the driver to your ear, in a comfortable way.
    - voldacar 7y ago
      That is incorrect. When I say "seal", I am referring to the sealed cavity between ear and driver, not to anything behind the driver. This is actually quite important for planars in particular, as a broken seal between the ear and driver leads to rapid bass rolloff, due to the lack of excursion found in most planar drivers (ime this is most noticeable with audezes since their excursion is especially low but I notice it with my HE-6 when I don't have the pads on my head quite right and there's a tiny gap between my head and the pads somewhere)

neves 7y ago

Looks like it will be impossible to play with someone else in the same room, right?

rodgerd 7y ago
Sure but you're already flailing around with a vision-blocking helmet, waving your hands. Noise pollution seems like less of a hazard for a bystander than getting whacked by the player.

cryptonector 7y ago

Oh, wow, this really is cool.

dmix 7y ago

> Humans in general are very sensitive to sounds within 2kHZ-5kHz range. If the frequency of a virtual sound doesn’t match up to what we expect it to be in reality, then we are more likely to identify the sound as “not real”. This is particularly true if you compare how easy it is to tell if someone’s voice is broadcast through a speaker vs. someone is talking beside you. I never thought about that in regards to gaming or even conference room voice chat, it is extremely easy to tell the difference. Must be a challenging problem set to solve, sounds fun!

tictoc 7y ago

How does sound affect us between receiving via headphones vs a speaker?