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Phased Array Microphone (2023)

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Re: Phased Array Microphone (2023)

#121

Post by aspenmayer »

gravypod wrote: post #11

I was just doing research and landed on this exact page last night! I was wondering if anyone knows how someone could mic a room and record audio from only a specific area. For my use case I want to record a couch so I can watch TV with my friends online and remove their speech + show noise from the audio. Setting up some array of mics and using them for beam steering would probably work but there's not a lot of exam…

You might look into OBS and/or VoiceMeeter to see how streamers selectively route audio while livestreaming/recording video/audio streams.

https://obsproject.com/

https://voicemeeter.com/

Re: Phased Array Microphone (2023)

#122

Post by derhuerst »

nielsole wrote: post #80
Marthinwurer wrote: post #27

Earlier quoted context omitted.

I love these kind of inadvertent measurements. One of my favorite examples is that a sufficiently accurate IMU can get you relatively accurate longitude measurements from the Coriolis effect.

Asahi Linux (and likely MacOS too) uses the resistance of the speakers coils to detect overheating of same speakers and reduces volume.

https://github.com/AsahiLinux/speakersafetyd

Re: Phased Array Microphone (2023)

#123

Post by refulgentis »

MVissers wrote: post #44
adamcharnock wrote: post #21

I would love to see this come to our various mobile devices in a nicely packaged form. I think part of what is holding back assistants, universal-translators, etc, is poor audio. Both reducing noise and being able to detect direction has a huge potential to help (I want to live-translate a group conversation around a dining table, for example). Firstly it would be great if my phone + headphones could combine the micr…

I believe modern macbook pro’s already have multiple microphones that probably do some phase-array magic.

Pretty much every device does, the trick always was if it actually worked, which Apple is assuredly great at. (source: worked on Google Assistant)

Re: Phased Array Microphone (2023)

#124

Post by morcheeba »

dchichkov wrote: post #75

I'm curious, why haven't you used TDM I2S microphones for your array and used PDM? I understand that ICS-52000 is a relatively low cost ($2/100pcs) and there are even breakout boards available with 4 microphones, which can be chained to 8 or 16, like https://www.cdiweb.com/datasheets/notwired/ds-nw-aud-ics5200... Then you can take Jetson (or any I2S capable hardware with DSP or GPU on it) and chain 16 microphones per…

Not OP, but I looked in to this a few years ago. It was more expensive then, and only went to 20 kHz. Higher frequencies are helpful if you're listening for the hiss of leaking gas, or corona discharge of an electric arc.

The Orin has 6xI2S ports internally, so that would work up to 16*6 = 96 microphones, which is a good number. But it looks like maybe only 3 are brought out & on different dev board connectors [1]? As with a lot of design, the devil is in the details. An FPGA could be easier to configure if you need more than 96 microphones.

My notes:

ICS-52000 $3.50, 20 kHz

ICS-41350 $1.05, 40 kHz

SPH0641LU4H-1 $1.45, 80 kHz+

[1] https://docs.nvidia.com/jetson/archives/r34.1/DeveloperGuide...

Re: Phased Array Microphone (2023)

#125

Post by quantadev »

adamcharnock wrote: post #21

I would love to see this come to our various mobile devices in a nicely packaged form. I think part of what is holding back assistants, universal-translators, etc, is poor audio. Both reducing noise and being able to detect direction has a huge potential to help (I want to live-translate a group conversation around a dining table, for example). Firstly it would be great if my phone + headphones could combine the micr…

In general the position of the microphones in space must be known precisely for the phase shifting math to be done well, and also the clocks on the phones would need to be in sync at high precision like 10x the highest frequency sound you're picking up. In other words within 10s of thousands of a second. Also if the array mic locations is not a simple straight line, circle, or other simple geometry the computer code (ie. math) to milk out an improved signal becomes very difficult.

Re: Phased Array Microphone (2023)

#126

Post by zipy124 »

brunosan wrote: post #5

Armchair comment. I would LOVE to be a grad student again and try to pair it with ultrasound speaker arrays, for medical applications. Essentially a super HIFU (High-Intensity Focused Ultrasound) with live feedback. https://en.wikipedia.org/wiki/Focused_ultrasound

I do my PhD in in-air ultrasound with phased arrays and talk to the medical guys at conferences/labs that we talk to and it's soooo much harder in solids/liquids. The frequency is significantly higher, think 1-10MHz instead of like 40khz, so any normal electronics are out the window.

Re: Phased Array Microphone (2023)

#127

Post by quantadev »

jensenbox wrote: post #119

Why a radial pattern and not a grid?

Because the distance between the mics needs to be 1) large and 2) consistent. It would work with a grid but the mics near the middle would be "underutilized" (not maximally taken advantage of), and also in a grid the mathematics is horrendous, but with a circle it's simple.

Re: Phased Array Microphone (2023)

#128

Post by quantadev »

killjoywashere wrote: post #13

I wonder how well this would work with laser microphones on a pane of glass. Can you infer keystrokes with near infrared laser? That is, can you identify the heatmap of keystroke events to infer which keyboard they're using, then replay the tape to identify the strings of characters being typed? Can you localize the turning of pages with UV?

This beamforming effect only works well when each sensor is getting a dramatic enough "different angle" on the signal that each one can use phase shifting to cancel out other noise, but with a laser there's not really any noise to cancel out (i mean you're just monitoring a vibrational spot on a window), and you also don't have a far enough "different angle" to shine from, if you're monitoring from one spot.

However having multiple lasers from multiple different locations might be able to create an improved signal if all signals are averaged, but it wouldn't really be due to the phase shifting that's used in beamforming.

Re: Phased Array Microphone (2023)

#130

Post by CamperBob2 »

derhuerst wrote: post #122
nielsole wrote: post #80

Earlier quoted context omitted.

Asahi Linux (and likely MacOS too) uses the resistance of the speakers coils to detect overheating of same speakers and reduces volume.

https://github.com/AsahiLinux/speakersafetyd

Interesting. If the voltage across the speaker voice coil can be sampled with enough sensitivity at a fast-enough rate, you have an undocumented microphone.
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