Aural Tone Generator with an arduino?

I am looking to make an aural tone generator using an arduino, and I kinda need some help to see if I can actually do this. I am not familiar with this item at all, but I do have an avionics background.
I have a car with some AEM aftermarket gauges that monitor fuel pressure, oil pressure, oil temp, water temp, boost, and Air Fuel Ratio, which output 0-5 Volts DC depending one what the signal value is.

Now what I would like to do is divide the gauge output into 2 groups, that is have an aural tone that goes off for HIGH voltage values, that allows me to know aurally that I have high oil temp water temp ect, and then an aural tone that goes of for LOW voltage values, which tells me I lost oil pressure, fuel pressure ect. I would also like to broadcast the 2 different aural tones through the cars stereo system, since it is rather loud.

Basically I was curious if this is possible at all with the arduino. As far as programming wise, I would need some help, as I know basic C++ with MS Visual Studio.

I have a couple of questions related to the arduino:
What is its limit in input voltage?
How can I output 2 different tones?
Is it possible to have tones with a voice over, like aircraft have with “terrain”?
Thanks
Look forward to the advice!
EDIT:
I should note that this would have no screen to monitor, so maybe a test button should be used as a press and hold, to run though a test sequence? Ideally what I would want is when I turn the car on, have the ardunio boot up within 15 secs. Thanks!

What is its limit in input voltage?

0-5V. If there is any possibility of your inputs going over 5V (or if there’s a chance it will go negative) use a [u]protection circuit[/u].

How can I output 2 different tones?

The tone() function can be used to generate various tones (one tone at a time).

Is it possible to have tones with a voice over, like aircraft have with “terrain”?
Thanks

The Arudino itself doesn’t have a digital-to analog converter and it doesn’t have a lot of memory, so you need an add-on audio shield for voice (or music).

In general, you mix two more digital streams (or files) by summing sample-by-sample. But, I don’t know the details of how to do it with an Arduino audi shield.

I should note that this would have no screen to monitor, so maybe a test button should be used as a press and hold, to run though a test sequence? Ideally what I would want is when I turn the car on, have the ardunio boot up within 15 secs. Thanks!

That should be no problem. But, you might want a little “test” switch or something rather than running-through a tone sequence every time you strt the car.

I would also like to broadcast the 2 different aural tones through the cars stereo system, since it is rather loud.

Hmmm… That could be tricky if you don’t have a separate amplifier. Then, you’ll need a mixer to mix the normal stereo audio with your tones. You can make a simple mixer with an op-amp summing amplifier.

It’s easy to make a summing amplifier, but you’ll have to make it work with a single 12V power supply, or you’ll need a DC-DC converter to generate a negative voltage. Op-amps “like” positive & negative power supplies although you can create a virtual ground and/or bias the input/output at about 6V so the signal can swing relatively positive & negative. Then, you need to filter the bias out of the audio signal.

Or, you can make a [u]passive mixer[/u] with a pair of equal-value resistors in each channel, but you’ll get signal loss.

Thank you for the information!
Sadly I am a bit overwelmed as I have no idea where to look or start. I have an idea in my mind on how the basics work, but as far as having it function, that is another detail I have no idea about.

Look at my post "piano tones micros" from last summer for creating multiple tones using blink without delay style programming.
Can pare it down for just 2 frequencies.