With the Double-Talk chipset you can pre-record your audio, and just send the address for the phrase that you want to play. You might be able to send out the bytes between interrupts. If I remember correctly, (I don't have my book with me here,) you have to end the play address with a 13, and the chipset will play whatever is stored at that address as soon as it sees the 13. This way you would only need to send out a few bytes each time.

Jerry.