• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Feedback control

Some cancellation techniques rely on interference. If you want to consider applying that sort of thing, measuring complex response will likely be instructive.

It's such a long time since I worked on this kind of thing in any detail. I'm likely way out of date.
 
I'm always working on it, since I can't control my earing aid from another computer I'm installing REW into my earing aid, that needs some boring adjustments :p
 
I struggle to install REW. Someone here know how to install REW on Debian ARM64?
 
1737467133759.jpeg
 
Hello Hayabusa :)

Capture test.jpg

Already tested and even improved but I'm sure we can do it better than that ;)

And before all, don't care about stigma, just think "best capture as possible" and "stop feedback waves":p
 
Last edited:
Not me.

There's also a support forum for REW. It might already have the answer.

Already read. One solution is to turn the OS to 32 bits but it won't be accurate about the DSP. Another solution is to install REW from another support than the OS, I'm exploring this way by now.
 
Hello Hayabusa :)

View attachment 422769

Already tested and even improved but I'm sure we can do it better than that ;)

And before all, don't care about stigma, just think "best capture as possible" and "stop feedback waves":p
Assuming a stationary setup, an other possibility is to have sound reflectors ( any flat surface ) positioned in such a way that the sound from the speaker arrives out of phase at the microphone.
 
Assuming a stationary setup, an other possibility is to have sound reflectors ( any flat surface ) positioned in such a way that the sound from the speaker arrives out of phase at the microphone.
Yeah sure

But what design would you advice? And about surface, would you use acoustic isolation? Phonic isolation? How would you do to attenuate waves diffraction and conduction from speakers to microphone? Which angle would you give to microphone?

That's a lot of questions
 
Yeah sure

But what design would you advice? And about surface, would you use acoustic isolation? Phonic isolation? How would you do to attenuate waves diffraction and conduction from speakers to microphone? Which angle would you give to microphone?

That's a lot of questions
I would do a practical experiment.
May be a glass plate TelePrompTer mirror?
Make the system oscillate, measure the frequency.
Calculate the wave length.
Put the plate at a place where the reflected path - the direct path is about half wavelength.
fine tune from there.
now again put up the gain and maybe find an other peak. Repeat.
 
Indeed, all my capture settings include absorption, reflection and diffraction. I've even tried to cut feedback by superposing straight and circular slots, horizontal or vertical in order to generate exctinctions by interferences but there is always some frequencies whiches are amplified and the complete extinction comes when microphone is almost encapsuled, sound capture is greatly damaged.
Yeah, I did that and more I'm sure you can't imagine, I even thought about microphones triangular diaphragm cause maybe the weak resonances can prevent feedbacks :rolleyes: I know I don't look earnest but I learn on the go and my last set is almost ready to allow me to reach quintessence ( philosophic way ). Actually, I've already reach quintessence when I listen to music cause no feedbacks ( I don't use the microphones ).
Microphones are very sensibles, large diaphragm and are placed next IEMs whiches deliver 50dB low and trebbles, and 80 dB mediums ( those levels are comfortable, I can increase and decrease a bit ). It's really hard to prevent feedbacks without DSP but it works well when I design the waves flow.

Just this fucking 2.5kHz feedback, in real situation, prevent me to use completely my left ear, and the right so because I need to balance stereophony. I cannot block this, and it's possible feedback comes by conduction, trough the ear support... Which case I've no solution...

And, I forgot to precise, I accept ideas about IEMs isolation :)

Unleash your imagination :D
 
Last edited:
Indeed, all my capture settings include absorption, reflection and diffraction. I've even tried to cut feedback by superposing straight and circular slots, horizontal or vertical in order to generate exctinctions by interferences but there is always some frequencies whiches are amplified and the complete extinction comes when microphone is almost encapsuled, sound capture is greatly damaged.
Yeah, I did that and more I'm sure you can't imagine, I even thought about microphones triangular diaphragm cause maybe the weak resonances can prevent feedbacks :rolleyes: I know I don't look earnest but I learn on the go and my last set is almost ready to allow me to reach quintessence ( philosophic way ). Actually, I've already reach quintessence when I listen to music cause no feedbacks ( I don't use the microphones ).
Microphones are very sensibles, large diaphragm and are placed next IEMs whiches deliver 50dB low and trebbles, and 80 dB mediums ( those levels are comfortable, I can increase and decrease a bit ). It's really hard to prevent feedbacks without DSP but it works well when I design the waves flow.

Just this fucking 2.5kHz feedback, in real situation, prevent me to use completely my left ear, and the right so because I need to balance stereophony. I cannot block this, and it's possible feedback comes by conduction, trough the ear support... Which case I've no solution...

And, I forgot to precise, I accept ideas about IEMs isolation :)

Unleash your imagination :D
Can you at least share your application?
Why does the speaker play your microphone sound?
 
Back
Top Bottom