Hi Andre,

The analog switch can only operate with analog voltages within its supply
rails. If your analog signal is 0 volts referenced it swings negative and
the analog switch cuts out. You can bias your analog signal as already
suggested.

Also you can use an NPN transistor(2N3904 or PN3904 works very well) to
short to ground the analog signal if the analog signal is less than .5
volts. Experiment with base resistors to reduce pop sound.

Cheerful regards,
Bob