Send signal of sound to small speaker

Hi,

I have a small speaker which has a P2 cable coming out from it. Usually I connect this P2 cable to my celphone or computer so it outputs sound to the speaker using the P2 cable/connection. See this:

|374x500

My question is this: I just want to send any kind of audio (square wave..., anything) to this speaker. Can I connect a digital pin from my arduino to send HIGH pulses to this P2 cable without any resistor or aditional hardware? I see this P2 terminal has 2 black stripes, how should I connect it to my arduino? Which part of this P2 terminal is GND?

And in precisely what respect is this a programming question?

Sorry, I am used to always post questions to this section, I forgot it was wrong.

Understanding TRS and Audio Jacks |500x150

I would put a capacitor in series with the signal to block DC bias. Other than that, you should be able to do that just fine.

I'm not sure how high line level voltages typically are though. There is a chance you might need to use a voltage divider to avoid overdriving the amp.

Send the signal to both right and left if you want Mono sound.