iCal default alert always Message with Sound? (10.7.3)

Please, can I have an option to change this setting? If I set the preferences to generate an alert with new events, it always has 2 alerts, one message and one sound (I think it is a recording of one of the mechanical parts of a MBP breaking 😉). Is that normal behaviour. I see it independent of the backend (local calendar, Exchange, Google, you name it.) Message is fine, but I don't want (any) sound.