515R making sound

Hi guys, I need some help with my 515R siren. 

So I hooked up the 515R siren to my existing viper alarm with a relay.  The alarm goes on when it needs to and works fine.  However, it sometiems makes a ticking sound when i drive.  For instance, when my RPM drops a little, the siren from the 515R makes a ticking sound.  It also makes a little ticking sound, as if it was to go off, when i turn on my head lights or high beams.  I'm pretty sure i connected the wires correctly to the relay.  Is this just the way it works?  or is it just making that sound because the car is drawign addtional current?  Thanks in advance for the help.