Is it possible to seperate the vocal sounds from music in mp3?

Speaking realistically, no. Music files are created by layering up
multiple tracks of sound, eg, vocals, guitar etc. To get a
satisfactory separation of the vocals you would need access to these
original tracks. Once they are mixed together they cannot be
separated, a bit like you can't turn toast back into bread.

Some software packages allow the vocals to be reduced, for the
creation of 'karaoke' tracks, which works by cancelling out the centre
of the sound where the vocals are usually placed. This process has
usually unsatisfactory results, and the track sounds as if its being
played underwater in some cases!

Hope this helps.

I would just like to support richeste1-ga's answer.  Music software is
getting better at this, but there is no real satisfactory solution.