Arduino controllable audio mixer

Using Arduino Audio
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Hello!

I am a newbie here but am hoping some of you out there can make some recommendations. I am working on a project to use an Arduino to control a stethoscope simulator for veterinary training. Part of this task will involve taking a series of audio streams (3-4), adjusting the volume of each stream, mixing them, and outputting them to a single speaker. I have been contemplating using a set of mono audio amplifiers

and controlling the volume of each amplifier using a digital potentiometer adjusted using the Arduino:
Digital Potentiometer - 10K - COM-10613 - SparkFun Electronics?

I would then need to find some sort of simple, cheap audio mixer to produce the speaker input. And that's the piece I'm struggling to find. Is there a simple IC audio mixer that I could use for this purpose? I assume just wiring all of the outputs to a single speaker would not work.

Thanks for any suggestions.
Dan Fletcher

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To me it sounds like this is something that should be done entierly in software that would run on a PC or MAC (and maybe even on a smart phone).

Writing an application for a computer isn't nearly as easy as writing an Arduino sketch, but you wouldn't have to build any hardware, and there would be no hardware reliability issues. And once you have one copy, you can make hundreds or thousands of copies at zero additional cost!

Is there a simple IC audio mixer that I could use for this purpose?

Something like [u]this[/u]? Or [u]this[/u]? And, maybe a multi-output [u]headphone amp[/u]?

I assume just wiring all of the outputs to a single speaker would not work.

Correct! The general rule is that you should never connect outputs together. However, it is generally OK to connect multiple inputs together such as connecting several amplifiers to the output of a CD player. (You can have trouble if you connect multiple speaker or headphone "inputs" to one amplifier, because of impedance loading.)