Sound sensor readings


#1

Hi,
can anyone tell me what do the sound sensor values stand for?
is it dB?


#2

No, it’s simply an electret microphone with a LM386 audio amp.

Checkout the wiki page:
http://www.seeedstudio.com/wiki/Grove_-_Sound_Sensor

You might find this one useful too:


#3

What does the electret microphone with a LM386 audio amp output? in other words, what does the “sensor value” in the python script actually measure? Is there a clear answer to this? Or is it simply a qualitative reading of surrounding sound?
(https://github.com/DexterInd/GrovePi/blob/master/Software/Python/grove_sound_sensor.py)

I followed the links, but I’m still having trouble understanding in laymen’s terms what the “sensor value” stands for.


#4

Hi @adevoid,

LM386 amplifies the low voltage that it is fed with from the Microphone, thus the output of LM386 is a voltage which is fed to the 10 bit ADC of GrovePi. The Sensor Value represents the ADC value of the voltage which varies between 0 to 1023. This is a relative value and hence it cannot be directly used for any speech based applications. If you wish to convert the values into decibels or Sound Pressure, you can refer to the link in this post.

Please let us know if this helps,
-Shoban


#5

Thanks, Shoban! Is this also true for the loudness sensor? Does its sensor value represent an ADC value?


#6

Hi @adevoid,

Sorry for the delay in reply, yes the Loudness sensor will also represent a 10 bit ADC value. Sound Sensor is just the amplification of all the sound that the amplifier receives, while the loudness sensor is the amplification of only the useful input signal, which gives a measure of the volume of the input signal. The loudness sensor has a two stage amplifier and a filter which removes high frequency noises, this is done in order to avoid unnecessary signal disturbances.

Please let us know if this helps,
-Shoban