Definitions!!

Some definitions according to the Oxford Dictionary:

Definition of decibel
noun
      a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale.

• (in general use) a degree of loudness: his voice went up several decibels

Definition of sound
noun
[mass noun]

1. vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear: light travels faster than sound

• [count noun] a thing that can be heard: she heard the sound of voices in the hall don't make a sound
• the area or distance within which something can be heard: we were always within sound of the train whistles

      2.  (also musical sound) sound produced by continuous and regular vibrations, as opposed to
            noise.

      3. music, speech, and sound effects when recorded and used to accompany a film, video, or 
          broadcast: [as modifier]: a sound studio

• broadcasting by radio a distinct from television.
• the distinctive quality of the music of a particular comp

          produced by a particular instrument: the sound of the Beatles

• (sounds) informal popular music: sounds of the sixties