My project is much bigger than simply an alarm for too high temperature, I'm making a terrarium + aquarium + indoor garden controller 
So what I really want is a sound device that can make a quiet "beep" when for example I press a button on the touchscreen, and a louder "BEEEEP BEEP" (but not too loud like a fire alarm!) for example when something goes wrong.
So I'm searching for a device that can emit beeps at different volume level and if possible few tones, I don't need something to play music (however I'm wondering if fishes and lizards love music :)), and if possible using 5V so I can connect it directly to Arduino (with a resistor if needed). With these data, can you recommend a model?
Thank you