Try another set of 'phones with the laptop.
If they sound OK, the problem is most likely to be
an incompatibility between connectors
(a rather rare occurrence, but not unheard-of).
Otherwise, the jack in laptop is wacky.
If so, curing it will not be a D-I-Y matter;
you would need to take the laptop to a
konfuzer repair shop for professional attention.
[From U.S. via Y!A Canada]