Hello everyone,
I've been planning to build my own dummy head for quite a long time now and am gradually comming closer to actually building the construct. The idea is to build a binaural microphone I can use for over ear headphone measurements (no IEMs) as much as for field recording.
The base will consist of a plastic mannequin head that is filled with compressed absorbing foam. As for the mics I will use some Primo EM172 electret capsules which are quite cheap and come with a great signal to noise and sensitivity. Linearity is decent for the price, as well. Maybe not the end of the road, but probably good enough for a hobby rig.
And then the heart of the matter: ear simulation.
I have finally found a pair of silicon ears which is somewhat average in size, realistic in shape and not too stiff. This should allow me to capture some generic pinna inteferences and directional bands. So far so good.
But what about the ear canal? Using pinna only, recording the sound somewhere in the concha cave, there will be no ear canal resonances which shape the timbre and are naturally processed by our brain trying to accomplish tonal balance.
There is a a lot of buzz around the net whether it is practically beneficial or not to model the ear canal.
Some say you can only get meaningful results when working with a state-of-the-art coupler by B&K or GRAS. Some say you can just use some generic 711 couplers from Taobao. Some say you just have to attach a plastic tube (18 to 25 mm long) to the ear to cover the fundamental resonances. And some say you don't need to worry about that at all because the canal is anatomically random anyway, shifting the resonant frequency in a unpredictable fashion.
After all, there is probably a piece of truth to all of them. But I wonder which of those options would fit best to my project.
To make it clear at this point: of course I can't reinvent the wheel or fit IEC standards and such with this rig. And I won't be so naive to expect any reliable correlation between the measured frequency response - depending on the impedance of the capsules, the flange and the coupling, the (here: random) shape of pinna and ear canal ecetera - and my personal perception. But I want try to account for the main requirements and difficulties for over ear measurements and expect a relative basis of comparison to judge overall tonal balance, changes with pads or varying case damping.
I know that there is no perfect standard, that even the recognized flagship couplers have their flaws and that there is also a lot of technical politics involved. And the more I read, the more I'm worrying about the usefulness of this rig. But I still do have hope that there is a practical solution that is good enough for the purpose and allows somewhat meaningful and repeatable results.
What are your thoughts?
Generic 711 coupler from Taobao? Plastic tube? Or just going completely without the ear canal?
I would welcome your response
Best wishes,
P48
I've been planning to build my own dummy head for quite a long time now and am gradually comming closer to actually building the construct. The idea is to build a binaural microphone I can use for over ear headphone measurements (no IEMs) as much as for field recording.
The base will consist of a plastic mannequin head that is filled with compressed absorbing foam. As for the mics I will use some Primo EM172 electret capsules which are quite cheap and come with a great signal to noise and sensitivity. Linearity is decent for the price, as well. Maybe not the end of the road, but probably good enough for a hobby rig.
And then the heart of the matter: ear simulation.
I have finally found a pair of silicon ears which is somewhat average in size, realistic in shape and not too stiff. This should allow me to capture some generic pinna inteferences and directional bands. So far so good.
But what about the ear canal? Using pinna only, recording the sound somewhere in the concha cave, there will be no ear canal resonances which shape the timbre and are naturally processed by our brain trying to accomplish tonal balance.
There is a a lot of buzz around the net whether it is practically beneficial or not to model the ear canal.
Some say you can only get meaningful results when working with a state-of-the-art coupler by B&K or GRAS. Some say you can just use some generic 711 couplers from Taobao. Some say you just have to attach a plastic tube (18 to 25 mm long) to the ear to cover the fundamental resonances. And some say you don't need to worry about that at all because the canal is anatomically random anyway, shifting the resonant frequency in a unpredictable fashion.
After all, there is probably a piece of truth to all of them. But I wonder which of those options would fit best to my project.
To make it clear at this point: of course I can't reinvent the wheel or fit IEC standards and such with this rig. And I won't be so naive to expect any reliable correlation between the measured frequency response - depending on the impedance of the capsules, the flange and the coupling, the (here: random) shape of pinna and ear canal ecetera - and my personal perception. But I want try to account for the main requirements and difficulties for over ear measurements and expect a relative basis of comparison to judge overall tonal balance, changes with pads or varying case damping.
I know that there is no perfect standard, that even the recognized flagship couplers have their flaws and that there is also a lot of technical politics involved. And the more I read, the more I'm worrying about the usefulness of this rig. But I still do have hope that there is a practical solution that is good enough for the purpose and allows somewhat meaningful and repeatable results.
What are your thoughts?
Generic 711 coupler from Taobao? Plastic tube? Or just going completely without the ear canal?
I would welcome your response
Best wishes,
P48