Audio Systems: DBW and Watts, power watts, dbw

Question
Hello my question is if 7 DBWs (Decibel Watts)is equal to 5 watts,does it take 5 watts to hear 7 decibels of sound?

Answer
No; a db is a ratio of one level to another. It is only absolute if referenced to a specific level.

For example, if an amplifier is producing 5 watts out for a given signal input and that input signal is increased such that the output power now goes up to 10 watts the increase in db is 3db.  In other words, 3db relates to a 2/1 power change.

Sound level is a completely different matter.  Acoustic energy does not relate directly to electronic power.

A useful specification to consider is loudspeaker sensitivity.  It is usually given in dbw.  And sensitivity is given as the sound level produced at 1 meter with a 1W input to its terminals.

This is a pretty good summary of the acoustic or sound power watts:

http://en.wikipedia.org/wiki/Sound_power

O db sound level is about the loudness of a whisper.

Does this help? Let me know if you need more.

C