Decibel & voltage formula

[introuble]

Hey I am writing an experiment which has a speaker connected to a power supply playing a continuous note. a decibel reader reads the volume from 0v to 12v. i know that as the voltage goes up so does the decibels but what theorem can i use to compare this with the results that will be recieved? thanks

 

[Eidos]

To convert voltage into decibels:
$$G_{\mathrm{dB}}=20\log V$$

Where $$G_{\mathrm{dB}}$$ is the value in decibels and V is the voltage measured in volts.

Thats log base 10 by the way :tongue:

 

[introuble]

To convert voltage into decibels:
$$G_{\mathrm{dB}}=20\log V$$

Where $$G_{\mathrm{dB}}$$ is the value in decibels and V is the voltage measured in volts.

Thats log base 10 by the way :tongue:

How would i use this? i am really confused atm lol

does it depend on the speaker size or not.

 

[Eidos]

Ok, start slowly.

What are you trying to measure?

My understanding is that you are playing a pure tone from a signal generator into a speaker. Then what?

I thought that the 0v to 12v was a voltage out across the speaker terminals that you wanted to convert to decibels.

 

[sirzerp]

A db to watt per speaker might be better.

 

[introuble]

Ok, start slowly.

What are you trying to measure?

My understanding is that you are playing a pure tone from a signal generator into a speaker. Then what?

then by a decibel reader i read the decibels from the speaker and and turn the voltage up and record the decibels again.

 

[Eidos]

Ok, so the decibels are from the sound and you want to find out the amplitude of the sound as a function of the amplitude of the voltage put into the speaker.

Is that right?

If it is:
$$A=10^{\frac{G_{dB}}{20}}$$ will give you the amplitude of the sound. The amplitude of the voltage is a known quantity then since you are putting that into your speaker.