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I have been looking at the idea of doing lots of small speakers with microphones on them attached to a fat lump of computer hardware, that you stick all over an

I have been looking at the idea of doing lots of small speakers with microphones on them attached to a fat lump of computer hardware, that you stick all over and they bleep each other and build an acoustic model of the space they are in, then adjust for it properly. Would basically be a self-modifying ambisonics system. It looks doable, though possibly a bit expensive.

e12e 11y ago
I believe there are some products in this space. It might be made simpler by integrating dac/dsp and amplifier in the speakers (and the just stream lossless digital audio for playback) -- rather than try and adapt to traditional speakers. It might be the kind of thing that the radical commoditization and continued price drop in hw will make feasible. Cinemas (and concert venues) do calibrate their sound, here's a sample link that touches on what's involved: http://education.lenardaudio.com/en/17_cinema_7.html http://education.lenardaudio.com/en/17_cinema_7.html I'm not sure a combined mic/speaker system makes much sense -- it would appear easier to just model what's important: how the sound sounds where the listener is -- which is typically anywhere other than on top of the speaker. Model a human head w/ears, but mics in each -- and hook that up to a system that plays/records/compares audio. While dynamically adapting (noise-cancelling when there's construction next door, the garbage truck rolls by?) -- I'm not sure that makes much sense. We're used to acoustics changing a bit -- but having a half-decent base-line would probably be great.
- lotsofmangos 11y ago
  Putting them in the speakers just limits the amount of extra things you you have to install, the idea is that in initial setup each speaker goes through a test pattern while the other speakers stay silent, and this gives you position of all the speakers and the acoustic properties of the space they are in. Though if you also have some extra microphones, then you can do dynamic adjustments on top and even account for people moving through the space so that they do not block sound or even so a stereo recording follows them around.
  - JonnieCache 11y ago
    Soundsystem techs commonly use a tool called SMART to calibrate a system to the room. It basically does impulse response measurement by blasting pink noise through a feedback loop and putting in various phase adjustments until the room has been cancelled out. It's a very delicate technique though. When you're talking about phase-aligning soundwaves you're sensitive to sub-millimetre alignment of your transducers.
mark_integerdsv 11y ago
Bang & Olufsen's Beolab speakers do pretty much what you are describing. They have a test tone and each one has a little micro dick (only way I can really describe it) that pokes out during the test tone playback to pick up reflections. More here: http://www.nytimes.com/2004/02/19/technology/how-it-works-a-speaker-that-adjusts-for-furniture-that-s-in-the-way.html http://www.nytimes.com/2004/02/19/technology/how-it-works-a-...
wintry757 11y ago
I recently bought the equipment to do a similar adaptive-audio job for my living room music / home-theater setup. I have the usual multi-decade collection of once-fashionable home stereo equipment, some in use, some collecting dust in the basement. I decided I needed a bit more bass to enjoy more thoroughly the gunshots and explosions of gameplay and epic action films. I listened to a stereophile friend eager to give advice, and convinced myself to add a self-powered subwoofer to the existing setup. Adding one shook the house but (to my ear) muddied the sound of music when no explosions were taking place. I could blame the equipment, or more properly myself, and replace some or all of the former. But I thought there must be some way to modulate all this unruly gear so that it produced a provably balanced and pleasant sound. I will skip over some intermediate steps where I tried to learn the science and engineering of acoustics, using a neutral reference microphone and several fine pieces of audio software available to all of us interwebbily. I learned that I was overdriving the subwoofer, which made sense, but I couldn’t seem to go from spectrum graphs and suchlike to an actual balanced sound system. My final setup worked out quite satisfactorily and is an affordable alternative to building the computer-driven speaker cluster for room modeling. > I have been looking at the idea of doing lots of small speakers with microphones on them attached to a fat lump of computer hardware, that you stick all over and they bleep each other and build an acoustic model of the space they are in, then adjust for it properly. When I played in a band, we had to work with the club’s sound engineer or bring our own to get a balanced sound setup before the audience showed up. The more recent gigs showcased an interesting technology, a system that generated pink noise through the actual sound system, from the original sound sources before the mixing board, all the way through power amplifiers to the speakers at front of house. The engineer put a reference microphone in a strategic position, turned on the pink noise generator, and twiddled equalizer knobs to get a roughly even spectrograph (plus unavoidable “sound-guy magic” to de-equalize somewhat for specific gig purposes like dancing or seated listening) for the whole room, using the actual speakers and sound-reinforcement equipment we would be using. This seemed to me to be the thing I needed in my home theater setup. It would let me balance and compensate for the (now) ten speaker cabinets in the living room (including the powered subwoofer), their real-life positions, the walls and floor coverings, the furniture, and even the cat. I think I could also do it with some combo of REW (Room Equalization Wizard) software, reference mike, and pink noise streamed through the amplifier. But while I was trying to get that approach figured out, I found a cheap piece of audio hardware with all that functionality built-in – no need to dedicate a computer to EQing the sound. This is the Behringer DEQ-2496, a configurable digital equalization gizmo. It has a room equalization function built in, which is a home version of the room-equalization setup we saw in the clubs, and as a bonus it basically automates the sound engineer’s fingers on the equalizer sliders. I am not sure if it’s the latest model supporting this function, as I got mine used, but it was well below $200 and probably the best money I’ve spent on pretending to be an audiophile. You set up the room for your listening preference (for me, this involves rolling the softest armchair into the center of the room the best to enjoy all those gunshots and explosions), put the reference mike about where your head will be, activate the automated room EQ process on the DEQ-2496, and sit down in your regular seating position to read for a while. It sends pink noise through the power amplifier and speakers and starts modifying an equalization curve to produce a “flat” room signal across all audible frequencies. After about 15-20 minutes the EQ settings stop changing and the Behringer has generated the EQ setup for acoustically-neutral room sound. You can save the setup and create others (e.g., for group seating), or modify it manually to match your preferences (bigger bass for film audio, slight high-frequency boost for classical music listening, etc.), and save the modified versions as well. All my digital sound sources pass through it (game consoles, video, and music) in digital format and are equalized before they hit the amplifier and speakers – just as it worked in the clubs. There are usable reference materials on the web to make up for the DEQ-2496’s obtuse user interface and execrable user manual. It’s not quite the super-flexible software-driven system I might have gravitated toward, but it does what I needed without tying up a computer. What I like most is that it deals with the real world sound of my setup and room – if I change my setup or furnishings (as has happened a couple of times), I just re-run the balancing process and use the new settings as the baseline for my preferred room EQ. If my subwoofer, say, is turned too high the Behringer sets up a balancing cut in the affected frequencies. If the carpet soaks up some high-frequency signals, they’re boosted to compensate. If my audiophile buddy gushes about the spectacularly flat frequency response of some new bookshelf system, I relax knowing that even my second-hand and slightly dinged-up speakers have been magically upgraded to subjectively flat (or not, as I wish) frequency responses – in the real world of my living room, not just in the lab or the store. It even has a full panel display of das blinkenlites should I need confirmation things are working properly. Very satisfying!

e12e 11y ago

I believe there are some products in this space. It might be made simpler by integrating dac/dsp and amplifier in the speakers (and the just stream lossless digital audio for playback) -- rather than try and adapt to traditional speakers. It might be the kind of thing that the radical commoditization and continued price drop in hw will make feasible. Cinemas (and concert venues) do calibrate their sound, here's a sample link that touches on what's involved: http://education.lenardaudio.com/en/17_cinema_7.html http://education.lenardaudio.com/en/17_cinema_7.html I'm not sure a combined mic/speaker system makes much sense -- it would appear easier to just model what's important: how the sound sounds where the listener is -- which is typically anywhere other than on top of the speaker. Model a human head w/ears, but mics in each -- and hook that up to a system that plays/records/compares audio. While dynamically adapting (noise-cancelling when there's construction next door, the garbage truck rolls by?) -- I'm not sure that makes much sense. We're used to acoustics changing a bit -- but having a half-decent base-line would probably be great.

lotsofmangos 11y ago
Putting them in the speakers just limits the amount of extra things you you have to install, the idea is that in initial setup each speaker goes through a test pattern while the other speakers stay silent, and this gives you position of all the speakers and the acoustic properties of the space they are in. Though if you also have some extra microphones, then you can do dynamic adjustments on top and even account for people moving through the space so that they do not block sound or even so a stereo recording follows them around.
- JonnieCache 11y ago
  Soundsystem techs commonly use a tool called SMART to calibrate a system to the room. It basically does impulse response measurement by blasting pink noise through a feedback loop and putting in various phase adjustments until the room has been cancelled out. It's a very delicate technique though. When you're talking about phase-aligning soundwaves you're sensitive to sub-millimetre alignment of your transducers.

mark_integerdsv 11y ago

Bang & Olufsen's Beolab speakers do pretty much what you are describing. They have a test tone and each one has a little micro dick (only way I can really describe it) that pokes out during the test tone playback to pick up reflections. More here: http://www.nytimes.com/2004/02/19/technology/how-it-works-a-speaker-that-adjusts-for-furniture-that-s-in-the-way.html http://www.nytimes.com/2004/02/19/technology/how-it-works-a-...

wintry757 11y ago

I recently bought the equipment to do a similar adaptive-audio job for my living room music / home-theater setup. I have the usual multi-decade collection of once-fashionable home stereo equipment, some in use, some collecting dust in the basement. I decided I needed a bit more bass to enjoy more thoroughly the gunshots and explosions of gameplay and epic action films. I listened to a stereophile friend eager to give advice, and convinced myself to add a self-powered subwoofer to the existing setup. Adding one shook the house but (to my ear) muddied the sound of music when no explosions were taking place. I could blame the equipment, or more properly myself, and replace some or all of the former. But I thought there must be some way to modulate all this unruly gear so that it produced a provably balanced and pleasant sound. I will skip over some intermediate steps where I tried to learn the science and engineering of acoustics, using a neutral reference microphone and several fine pieces of audio software available to all of us interwebbily. I learned that I was overdriving the subwoofer, which made sense, but I couldn’t seem to go from spectrum graphs and suchlike to an actual balanced sound system. My final setup worked out quite satisfactorily and is an affordable alternative to building the computer-driven speaker cluster for room modeling. > I have been looking at the idea of doing lots of small speakers with microphones on them attached to a fat lump of computer hardware, that you stick all over and they bleep each other and build an acoustic model of the space they are in, then adjust for it properly. When I played in a band, we had to work with the club’s sound engineer or bring our own to get a balanced sound setup before the audience showed up. The more recent gigs showcased an interesting technology, a system that generated pink noise through the actual sound system, from the original sound sources before the mixing board, all the way through power amplifiers to the speakers at front of house. The engineer put a reference microphone in a strategic position, turned on the pink noise generator, and twiddled equalizer knobs to get a roughly even spectrograph (plus unavoidable “sound-guy magic” to de-equalize somewhat for specific gig purposes like dancing or seated listening) for the whole room, using the actual speakers and sound-reinforcement equipment we would be using. This seemed to me to be the thing I needed in my home theater setup. It would let me balance and compensate for the (now) ten speaker cabinets in the living room (including the powered subwoofer), their real-life positions, the walls and floor coverings, the furniture, and even the cat. I think I could also do it with some combo of REW (Room Equalization Wizard) software, reference mike, and pink noise streamed through the amplifier. But while I was trying to get that approach figured out, I found a cheap piece of audio hardware with all that functionality built-in – no need to dedicate a computer to EQing the sound. This is the Behringer DEQ-2496, a configurable digital equalization gizmo. It has a room equalization function built in, which is a home version of the room-equalization setup we saw in the clubs, and as a bonus it basically automates the sound engineer’s fingers on the equalizer sliders. I am not sure if it’s the latest model supporting this function, as I got mine used, but it was well below $200 and probably the best money I’ve spent on pretending to be an audiophile. You set up the room for your listening preference (for me, this involves rolling the softest armchair into the center of the room the best to enjoy all those gunshots and explosions), put the reference mike about where your head will be, activate the automated room EQ process on the DEQ-2496, and sit down in your regular seating position to read for a while. It sends pink noise through the power amplifier and speakers and starts modifying an equalization curve to produce a “flat” room signal across all audible frequencies. After about 15-20 minutes the EQ settings stop changing and the Behringer has generated the EQ setup for acoustically-neutral room sound. You can save the setup and create others (e.g., for group seating), or modify it manually to match your preferences (bigger bass for film audio, slight high-frequency boost for classical music listening, etc.), and save the modified versions as well. All my digital sound sources pass through it (game consoles, video, and music) in digital format and are equalized before they hit the amplifier and speakers – just as it worked in the clubs. There are usable reference materials on the web to make up for the DEQ-2496’s obtuse user interface and execrable user manual. It’s not quite the super-flexible software-driven system I might have gravitated toward, but it does what I needed without tying up a computer. What I like most is that it deals with the real world sound of my setup and room – if I change my setup or furnishings (as has happened a couple of times), I just re-run the balancing process and use the new settings as the baseline for my preferred room EQ. If my subwoofer, say, is turned too high the Behringer sets up a balancing cut in the affected frequencies. If the carpet soaks up some high-frequency signals, they’re boosted to compensate. If my audiophile buddy gushes about the spectacularly flat frequency response of some new bookshelf system, I relax knowing that even my second-hand and slightly dinged-up speakers have been magically upgraded to subjectively flat (or not, as I wish) frequency responses – in the real world of my living room, not just in the lab or the store. It even has a full panel display of das blinkenlites should I need confirmation things are working properly. Very satisfying!