Can you use an Inverter IC chip to change two speakers automatically?

I am making a snowmobile helmet that will have an Ipod and walkie talkie. I want my ipod to play the entire time, but once I get a message from my walkie talkie I want the music to stop. I was thinking of doing this by using the highs and lows of the two signals and put them through an inverter IC chip. I was going to use a 74LS04. My question is would the signals come out of the inverter as understandable signals and would this even work ? 

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I think a multiplexer IC
http://en.wikipedia.org/wiki/Multiplexer
is what you want.  Such  a device has 2^n (usually 2, 4, or 8) analog inputs, one analog output, and n digital address bits for the purpose of selecting one of the 2^n analog inputs and connecting it to the output.

That wiki article gives a list of 74xxx series multiplexer ICs. 
http://en.wikipedia.org/wiki/Multiplexer#List_of_ICs_which_provide_demultiplexing
The CMOS ones are numbered similarly, e.g. CD4xxx, 74HC4xxx, etc.  Guessing you want the one that comes with 4 2-input muxes, or maybe the one that comes with 2 4-input muxes, since you have two channels (left and right)  you want to switch at the same time.

The multiplexer would take care of the actual switching problem, but then you also need some sort of detector circuit, that is a circuit that will respond to time-averaged amplitude of an audio signal, and give a digital output, e.g. the output goes high when it detects a signal, and is low otherwise.  Then this digital output from your detector(s) is used to drive those address inputs on the mux, i.e. tell it to switch.
I don't see how you would stop the player playing with this. Do you have a remote for it ?