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פיסיקה של קול ובינה מלאכותית

 

practical estimate for ICS-43432 / ICS-43434:

 

Sound at mic Expected I2S level CNN detection efficiency
120 dB SPL 0 dBFS  Clipping, bad for AI
100 dB SPL −20 dBFS  Excellent
94 dB SPL −26 dBFS  Excellent
80 dB SPL −40 dBFS  Very good
70 dB SPL −50 dBFS  Good
60 dB SPL −60 dBFS  Medium/good
50 dB SPL −70 dBFS  Weak, needs filtering/FFT
40 dB SPL −80 dBFS  Poor, only if quiet background
30 dB SPL −90 dBFS  Near mic noise floor, unreliable

For drone CNN detection:

I2S level Practical CNN result
−20 to −45 dBFS Very strong detection
−45 to −60 dBFS Good detection if trained well
−60 to −70 dBFS Possible with band-pass + FFT/log-mel
−70 to −80 dBFS Weak, many false detections
Below −80 dBFS Usually not reliable

Best target for your drone system:
keep drone signal around −40 to −65 dBFS at the mic input.

in our code :  I2S mic, the important one

int32_t v8 = raw[i] >> 8; //  Because the mic audio is usually 24-bit inside 32-bit I2S.

24-bit sample min = -8,388,608
24-bit sample max = +8,388,607

   Based on your code, raw[i] is int32_t, so absolute theoretical range is:

Value in code

 

 Minimum possible Maximum possible
raw[i] −2,147,483,648 +2,147,483,647
raw[i] >> 8 −8,388,608 +8,388,607
raw[i] >> 16 −32,768 +32,76

24-bit sample min = -8,388,608

24-bit sample max = +8,388,607

 

dBFS means decibels relative to full digital scale.

 

RMS_sample Average audio signal strength
Full_scale Maximum possible digital value

For 16-bit audio:

Example:

Calculation:

So the signal is 9.24 dB below maximum digital level.

 

getting the rms   RMS_sample

RMS = sqrt( average(sample²) )

 

For real-time I2S mic RMS, use a window of:

 

 

RMS samples Time at 16 kHz Use
128 8 ms very fast, noisy
256 16 ms good real-time level meter
512 32 ms better stable RMS
1024 64 ms very good for mic/audio level
1600 100 ms good for AI / drone detection
2048 128 ms smoother, more delay

 

how to estimate SPL from your samples

https://d17t6iyxenbwp1.cloudfront.net/s3fs-public/2026-04/ds-000038-ics-43432-datasheet.pdf?VersionId=veAhamtZ3HRY0lMilS5lPSHZqZUVD.rR