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I want to calculate the Sound Pressure Level (SPLdB) of My PC headphones. My headphone specs says:

Maximum Power Input = 50 mWatt
Rated Power = 25 mWatt
Impedance = 32Ohm
Sensitiviy = 100dBSPL/mWatt

I used the formula

SPL(Pa) = Sensitivity * Power (A)


SPL(dB) = 20 Log (SPL(Pa)/(2 * 10^-5)) (B)

My questions are:

  1. In formula (A) Which Power I have to use Maximum or rated?

  2. The specs given at start are related to headphone only. PC soundcard output (say a fixed volume is selected at system volume control) does not play any role?

  3. Are the given formulas correct? I have obtained them from googling.

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migrated from Jan 27 '14 at 15:06

This question came from our site for engineers, producers, editors, and enthusiasts spanning the fields of video, and media creation.

The only way to truly determine the SPL level of your headphones is to have it measured with a specialized device that goes in the ear while listening. Generally it's pricy, but an audiologist would probably have one. It's part of the fun of headphones and in-ears particularly. They are really hard to get an accurate read of effective SPL due to how the sound enters the ear.

You can get a conservative approximation by holding a normal SPL meter directly up to the driver of over the ear type since part of the sound from them isn't going to make it in, but with in-ears, there is no effective way to know short of in-canal metering.

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