Special positioning requires physical space. My listening room is pretty close to a natural human scale. It is about 20 feet wide and 30 feet long. A little larger might be a bit better. You don’t get that with either headphones nor IEMs.
4-5 groups of drivers would work best and any sound pattern should be in principle achievable (the main point I tried to argue for and which theoretically holds)
I have nu clue what you mean by this, where you get this from, or what theory you are talking about(?). I would think one driver per ear can be enough.
Is it maybe marketing talk from some company?
I have nu clue what you mean by this, where you get this from, or what theory you are talking about(?). I would think one driver per ear can be enough.
Is it maybe marketing talk from some company?
If "marketing talk" is your mentality, I am sorry to disappoint you that I am talking from the practical experience and my own thinking. Your clues are your own business...
The practical experience - multiple BAs work great, these drivers shine in specific frequency ranges of 2-3 octaves.
The group of drivers is for the spatial domain.
Multiple drivers is usually to optimize each driver to a specific frequency range in response. Better response may unmask secondary depth cues, but it won’t create primary distance cues. The spaces between the drivers and the eardrum with IEMs and headphones are minuscule. Not like the 8 to 10 foot distances we’re talking about with speakers. Soundstage requires physical distance in feet, not centimeters. It also requires walls and a room. You can’t fit all that in your ears!
Multiple drivers is usually to optimize each driver to a specific frequency range in response. Better response may unmask secondary depth cues, but it won’t create primary distance cues. The spaces between the drivers and the eardrum with IEMs and headphones are minuscule. Not like the 8 to 10 foot distances we’re talking about with speakers. Soundstage requires physical distance in feet, not centimeters. It also requires walls and a room. You can’t fit all that in your ears!
It is harder to fit definitely.
If you are familiar with DLP arrays, that are found the best success in projectors, quite a bit is possible, e.g. piezo arrays.
Again, being close to the detector makes it easy to generate the desired wave pattern, but is definitely more challenging with the requirements for precise positioning.
I once asked a chief engineer at a studio if they had any good headphones. He said they bought a pair when they opened for business in case a client wanted them, but they were still in a cupboard unopened. They had a pile of beater headphones they used for isolation when recording though.
If "marketing talk" is your mentality, I am sorry to disappoint you that I am talking from the practical experience and my own thinking. Your clues are your own business...
The practical experience - multiple BAs work great, these drivers shine in specific frequency ranges of 2-3 octaves.
The group of drivers is for the spatial domain.
An unpopular opinion on the forum, but mine anyway: a single dynamic driver, well vented with a competent acoustic tuning, will tend to outperform the best efforts of multi BA drivers. I reach out to BA IEMs myself, but only because I want something small and isolating while on the go. 2 things BAs are ideal for. But for most variables of fidelity, a better option can be found. And we're back to having to define our reference. If SNR from outside counts, then BAs are less often defeated. And if we envision a loud environment, then a fully sealed ear canal becomes the objective winner at all time.
About space or impression of space, what matters is the sound pressure at each eardrum. if one transducer can give one eardrum the right signal, then we don't need more.
An unpopular opinion on the forum, but mine anyway: a single dynamic driver, well vented with a competent acoustic tuning, will tend to outperform the best efforts of multi BA drivers. I reach out to BA IEMs myself, but only because I want something small and isolating while on the go. 2 things BAs are ideal for. But for most variables of fidelity, a better option can be found. And we're back to having to define our reference. If SNR from outside counts, then BAs are less often defeated. And if we envision a loud environment, then a fully sealed ear canal becomes the objective winner at all time.
About space or impression of space, what matters is the sound pressure at each eardrum. if one transducer can give one eardrum the right signal, then we don't need more.
Actually, the superiority of single-DD IEMs is the current dominant opinion - my perception from multiple IEM threads.
A clear advantage of the single DD is the timbre, while BAs are superior in resolution, often at the expense of the timbre/coherence.
I am personally much more into the resolution, hence BAs for me. I do like the recent generation of vented BAs with less "vacuum" seal, less isolation but more comfort.
For the resolution, one driver working at all the frequencies is challenging. There are violins, violas, cellos and DBs and not a single "play it all" string instrument for a good reason of natural resonances and avoiding cross coupling.
Having multiple drivers both in the frequency domain (what is actively implemented now) and spatially (multiple channels similar to 5.1 etc) should provide most flexibility for the sound reproduction.
I have a set of KEF speakers where the different drivers are nested in a radial design. The idea has something to do with aligning waves from the source... Not sure exactly how it works but they sound great.
Having multiple drivers both in the frequency domain (what is actively implemented now) and spatially (multiple channels similar to 5.1 etc) should provide most flexibility for the sound reproduction.
Do you listen to five IEMs from the other side of the room? It seems to me that once you put a multi driver IEM in your ear, it's operating as a single sound source.
If "marketing talk" is your mentality, I am sorry to disappoint you that I am talking from the practical experience and my own thinking. Your clues are your own business...
Sorry if I sounded a bit offensive, apologies. I actually was curious what you meant exactly and if you were thinking there is a connection with sound localisation.
And your next statement shows that you do:
Having multiple drivers both in the frequency domain (what is actively implemented now) and spatially (multiple channels similar to 5.1 etc) should provide most flexibility for the sound reproduction.
About space or impression of space, what matters is the sound pressure at each eardrum. if one transducer can give one eardrum the right signal, then we don't need more.
That doesn't mean you could not use seperate sets of drivers for additional channels, but by itself that won't make you perceive them as differen channels at a different location, and the other way round: it is not needed for simulating different channels.
But I guess you could feed the different sets of drivers each with a binauralised signal for a different channel, so that each set has less work to do. Not sure if that would have a real advantage though.
@PhonoPhi: just in case you are wondering how you would simulate a multichannel speaker system with one driver (or one set of drivers together reproducing one headphone input channel) in each ear the following quote may be usefull:
You have only 2 ears, yet you can hear where sound is coming from (within certain limitations of course). The brain uses all kind of information to determine that, and I could mention them all here but actually you don't even need to know exactly what it is. All that needs to be done to recreate the same experience as listening to 16 speakers in a room is making sure that the exact same signals that enter your ears when you listen to real speakers will enter your ears when listening to NORMAL STEREO headphones. That is what the realiser does. It measures the total net result that enters your ears as a result of the testsweeps being played over the speakers (per speaker per ear, so in fact 2x16 "transfer functions"), including all colourations from bending around your head and into your ears, including all reflexions and reverberations and their colourations from bending etc. etc.
With the result of this measurement (the PRIR) the Realiser can later apply the same changes to any source signal (music or whatever in any of the supported formats from mono to multichannel) you feed to it, creating the sensation of hearing the same source signal being played over the speakers.
Digital Signal Processing creates a stereo signal intended for the headphone based on up to 16 input signals and 32 channel to ear transferfunctions, a abstract description of what it calculates (without taking the headtracking into account) could be:
@PhonoPhi: just in case you are wondering how you would simulate a multichannel speaker system with one driver (or one set of drivers together reproducing one headphone input channel) in each ear the following quote may be usefull:
Surely, one driver can be used.
Yet, there are limitations of resonances, cross-couplings, etc.
One membrane can hardly practically vibrate perfectly as needed to reproduce music in 3-decade range of 20 Hz to 20 kHz.
Then a lot of efforts is involved in DDs to make them work better, as mentioned - very strong field, multiple coils, compensation...
To me an array of small drivers each working in a well-defined limited range of 2-3 octaves is a more flexible solution.
I tend to think that a multi driver IEM is probably good if it's well implemented, not because it's multi driver. A well implemented single driver would be good too. We're talking about tiny little drivers, not huge woofers that need to fill a whole room. It isn't impossible to make a single full range driver, and clearly there are single driver models that sound great. I have planar magnetic headphones. A lot of people say planar magnetic is better than regular dynamic cans. But I've heard dynamic headphones that sound just as good as my PMs. There really isn't one aspect that makes a design good. It's the balance of all the aspects.
But all this is about response, not dimensional soundstage or sound fields.
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