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Sensortile Mic Level

Question asked by MADHUSUDAN G on Dec 21, 2017

What is Mic level in sensor tile represent ? The audio noise in db in particular as per this formula 


DBNOISE_Value_Ch[NumberMic] = (uint16_t)((120.0f - 20 * log10f(32768 * (1 + 0.25f * (AUDIO_VOLUME_VALUE /*AudioInVolume*/ - 4))) + 10.0f * log10f(RMS_Ch[NumberMic])) * 0.3f + DBNOISE_Value_Old_Ch[NumberMic] * 0.7f);


How did you arrive at this formula ? The acquired PCM sample values are squared and then divided as per this formula 


RMS_Ch[NumberMic] /= (16.0f*MICS_DB_UPDATE_MUL_10MS*10); which is the mean calculation and how does this relate to RMS value?


Can we use the PCM sample values to calculate the Sound pressure level and classify the sound ?