switching - Detecting state of LED to control another circuit

I need to add functions to equipment I am not allowed to modify in any way. To do this I need to monitor the status of a Yellow/Amber LED and translate its status into a signal that can be used to turn on or off a loud alarm speaker. I will use a klaxon for the speaker. My issue is that I only want to detect the light from the LED and not have sunlight or florescent lighting turn on the speaker. I would like to be able to still see the original LED, but if necessary to cover it, I could add another LED to the device. I would power from either 5V, 12v, or 24v dc. Any help would be great. Once I get some ideas, I will experiment if necessary.
Thanks, Bcrumb