squeaky ish suspension

hey
anyone know whether its normal to hear, an 'escaping air' sound when you rock back and forth on your bike?
In other words should the shocks be totally silent when they compress? or should you hear the sound of escaping air.
And would this mean your shocks need new oil??
cheers
anyone know whether its normal to hear, an 'escaping air' sound when you rock back and forth on your bike?
In other words should the shocks be totally silent when they compress? or should you hear the sound of escaping air.
And would this mean your shocks need new oil??
cheers