If you can get into the device it should be as simple as de-soldering the two wires connecting the speakers to the main board. Then you would need to get a replacement speaker of the same size and power as the one already in the device which may or may not be a propriety size speaker.
The hard part would most likely be figuring out how to open the speaker which I cannot help with since I don’t own one and have never worked on one. This procedure is just how I have changed speakers in multiple different PC speakers or iHome type devices.