convertir señal de un microfono a decibeles

[AlfredoHr5]

buenos dias, tengo un problema con un vi que estoy haciendo, caundo adquiero la señal desde la daq me la muestra en mV y quiero que se muestre en decibeles pero he investigado y no encuentro como hacer la con version para que me de el valor en decibeles.

la sensivilidad es de 45 mV/Pa y utilizo una daq dt9837.

[santo_13]

Decibel is a relative value and does not have a unit of its own.

For example, in Acoustic 94dB SPL denotes the 1Pa pressure compared to 20uPa pressure. Notice the term "SPL" that is the unit and there is always a reference level which in this case is 20uPa.

In your case, you can convert the voltage you measure into Pa by multiplying the sensitivity.

For example, if you measure 45mV RMS value, it will be 1 Pa pressure. But if you need to convert this 1 Pascal to dB you need a reference value to compare against.

If your reference is 1 Pa, then 45mV rms will be 0dB re1Pa

If your reference is 20uPa, then 45mV rms will be 94dB re 20uPa

As you may be aware, the sensitivity is required to convert the electrical signal (voltage) into Engineering units (Pascal)

So, the reference level is essential to convert the value from Engineering units to dB

You can convert dB using the below formula, 

Value in dB = 20 * log (measurement in Pa / reference measurement in Pa)

[AlfredoHr5]

ya entiendo,¿entoces podria convertir los mV medidios del microfono en un ambiente normal y usar eso como nivel de referencia.?

[santo_13 · Accepted solution]

Good that you mentioned that it is audio, then reference levels are industry standard at 1V/Pa, 20uPa, 94dB SPL

Depending on whether you need dBV or dB SPL, the calculations vary.

dBV measurements are relative to 1V rms i.e., 1V/Pa

dBV = 20 * log (amplitude Vrms)

dB SPL measurements are relative to 20uPa rms

signal in Pascal = Amplitude rms / sensitivity

dB SPL = 20 * log ( signal in Pascal / 20e-6)

[AlfredoHr5]

muchas gracias, con la infomacion que me explicaste ya tengo una idea mas clara de como llevar acabo el programa. gracias de nuevo.