Hey guys im a noob at electronics. I have a 8 ohm .5 watt speaker connected to two triple A batteries and i want to use the speakers output to trigger events…where do i start?
What's that circuit board? Does it make sound?
i want to use the speakers output to trigger events....
Normally, a speaker is an output-device. It converts electrical signals to sound. A microphone is an input-device. It converts sound to an electrical signal, so you could use microphone to "trigger something".
BTW - You can't driver a 4 or 8 Ohm speaker (to make sound) directly with the Arduino. You need an amplifier or driver circuit (normally a linear audio amplifier). The minimum impedance/resistance on an Arduino output pin is 125 Ohms.
I'm pretty sure that's not a 5W speaker in your picture. Maybe 0.5W. 
The circuit board is from a game. The circuit board itself does not make sound…You’re right its a 0.5w speaker and it makes preprogrammed sound…(i want to detect specific current/sound that it is outputting with an arduino then use that specific pattern to trigger a buzzer or something…not quite sure what i want it to trigger yet.
So i’ll need an “amplifier or driver circuit (normally a linear audio amplifier)” to enable an arduino to pick up low current? Or i could just use a microphone to pick up the sound? For some reason i was trying to stay away from using a microphone because i feel like ambient noise might mess up the trigger…but im a noob 
Thanks alot for this help btw!
If you want the Arduino to distinguish one sound from another - then just forget it. The best you will be able to do is to estimate volume. 
Paul__B:
If you want the Arduino to distinguish one sound from another - then just forget it. The best you will be able to do is to estimate volume.
That depends upon the sound of interest. 8-bit AVR Arduino's can do tone detection for instance and there are examples of touch tone decoding on the web.
It's possible to use a speaker as a microphone with a suitable amplifer, but rarely is it a better choice than using a suitable microphone for the purpose. For an "electronic noob" it adds an unnecessary level of complication and opportunity to go wrong. In my experience the MAX9814 based microphone modules are a good choice for producing Arduino compatible output signal levels for reasonable sound volumes.
MrMark:
In my experience the MAX9814 based microphone modules are a good choice for producing Arduino compatible output signal levels for reasonable sound volumes.
as you mentioned - and was followed up here. 