i got the value of sound in watts.
How can i do to make it in db?
whether the constant multiplier 4.343 is correct ?
but a calculator value mismatched with multiplied value.(log value)
which is correct to convert a number in db?
First you need to know how many real RMS Watts are peoduced by your amplifier into the exact impedance of your loudspeakers. Many amplifier manufacturers quote phoney Whats instead of real Watts.
Then you must measure the distance from your speakers to your sound level meter and subtract dB's for the distance. The acoustics of the room affects certain frequencies.
Then you calculate the sound pressure level by using the spec'd sensitivity of your speakers.
That's not really accurate. There is still a heavy frequency change for human hearing even at relatively loud levels of SPL. Attached is the standard "equal loudness" curve for human hearing I have always seen used for reference. You see large magnitude changes from low frequency to high even at the highest SPL level on the chart which is 120 dB. That is a pretty loud level, most people would not like to hear it for long. At SPL levels which are nearly deafening, the frequency contour does continue to get flatter but it has to be dangerously loud.Never mind dBA which uses A-weighing. A-weighing is a filter used to remove most low frequencies and some high frequencies from low level sounds because our hearing's sensitivity does that.
At loud levels the filter should not be used because the response of our hearing is almost flat.