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Any comodity USB sound card but rather than some off the shelf passive mic use active analogue modules as the Pi has the power sources.
Enermax mentioned as its stereo ADC but mono is just as valid as is also how many mic modules you use on a input.
Most soundcards get a bad reputation not because of the mic input but because the passive mic used is relatively insensitive.
You can get relatively sensitive active mic modules , some are much better than others but all are not much more than a few $ and really lend themselves to those who are going to DiY an enclosure.
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The respeaker card drivers (not usb versions) lock you down to a specific kernel version and why its shoddy is actually there would seem to be no real reason apart from they have chosen to do so.
The simplesoc drivers they use are very similar to the free drivers adafruit use and its bit of a mystery to me why they are so problematic with common linux software like pulseaudio.
There is also a slight bit of snakeoil with all the far field microphones where command voice has to be the predominant volume.
The work great in distrubtuted noisy environments where the command voice is predominant or from a distance in silence.
Across what can be very common noise sources such as TV or HiFi where the command voice becomes less predominant far field recognition reduces drastically.
They do work but tend to be high value comodity product that don’t work as well in common situations as many presume.
Prob the 2mic Respeaker is the best as its cheap and if the drivers bug you it was cheap.
USB wise they tend to completly throw out of whack where I would see a completed voiceAI land price wise.
Matrixvoice never tried as think for price its a crazy solution.
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Cheapest route is the Pi has an I2S interface and x2 I2S mems mics can be sourced for a couple of $ download the adafruit drivers and there you go.
Analogue use on a soundcard, I2S use if you don’t have a sound card. There is another I2S interface on the PI but I think its purely a current driver problem that they conflict with things like 4x I2S mics or 2x and a DAC.
I don’t know the full in and outs of I2S spec but you can not ‘daisy’ chanin I2S mics like you can parallel analogue.
On the Pi it send left/right in a low bytes / high bytes so as well as the interface clk it also has a channel clock where x2 I2S mics will multiplex in the low/high bytes of the I2S word.
With a single mic one is just missing.
Passive mics just send a very low level signal to a soundcard that is then amplified and often the gain and level on the sound card doesn’t give great gain and the signal is very susceptible to noise (actually the noise is just amplified geatly as the signal is)
Active mic is just a little gain circuit at the mic source where the oppisite is true, less likely to pick up noise as the signal is much bigger and will need much less amplification on the soundcard.
I said above some are better than others but its more a matter of getting a reasonable match in signal level and soundcard amplification.
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So here is a recap and because the high end offerings are not all that spectacular in terms of price hike some see the lower cost offerings as acceptable and even preferable.
Prob easiest is any USB soundcard with and active mic as the passive sensitivity can be lack lustre and low.
Anything other than mono on USB audion seems to be extremely rare apart from the edimax that does give the possibility of 2 channels and any number of summed mics on a channel if you wish.
If your not bothered about HiFi quality but just want resonable voice output then the 3.5mm is acceptable and all you need is 2x I2S mics and it creates a very cheap and effective system.
If you then think that 3.5mm audio wise is a bit damn awfull you can still have an upgrade to a hdmi2hdmi+audio without making your I2S mics a waste of time and money.
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This is just opinion but self contained singular consumer array microphones are probably a misnomer as essentially the where the consumer encapulation of wide array conference microphone systems into a single consumer unit via some heavy DSP lifting that many still struggle to do well with what is available.
Due to the speed of sound its pretty obvious the distance it takes between mics on a small consumer array units a couple of inches in diameter is much different to the distance a wide array conference room as it quickly changes from sub millisec processing time to a few millisecs.
Then you get predominant noise interference where a wide array has a huge advantage as 1 mic is likely to be nearer to noise and another is nearer to command voice and cancelation and detection is hugely simplified by positioning.
We have a current fad of trying to shoehorn audio capture in singular consumer devices where it can even be more costly than several wide array capture points and in many ways it doesn’t make any sense and its likely we will see more satellite systems become the norm as they are better by pure and simple physics of sound, distance and positioning.
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Respeaker 2 mic.
Is a great little piece of hardware all-in-one button, mics, i2c, audio out and a couple of leds.
Brilliant piece of hardware such a shame about the drivers as without doubt if they sorted them its a killer $10 HaT.
It allows you to stick it on a Pi and go. Only problem after that for many is how to get it into an enclosure effectively. Brilliant if your going to just stick on a Pi but from a point of an enclosure you left scratching your head of why they created it so.
Some of us like the more DiY options as even if it does take a soldering iron and a bit of building its actually far more felixible and dependending on skill levels can give some really polished end product.
Many when first viewing see cards and high end modules as far superior but get to the end of a project or 2 this can often change.
Same with EC many don’t think its needed then after completeion some media playing activity comes to the fore and getting the thing to stop apart from walking up to the mic and screaming “Stop” does little.
I have a 2 Mic and 4 mic respeaker on my desk gathering dust and yeah they where great but that is all they are likely to do now (gather dust) they are a great all in one starter but very inflexible in terms of a finnished enclosure unless that is all you want as apart from the driver the 2 mic is great.
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