Use MP3 Player. VS1053B. I use it for my Biometric Attendence System. It plays mp3 files like "Attendence Registered", "User Enrolled", etc...
I use MP3 Click from mikroElektronika for my products but you can put the MP3 circuit on your board. Here in India we don't get modules like MP3 Click or MP3 Shield and also it is difficult and costly to get SMD components based boards manufactured and assembled and so I use mikroE products.
In the mikroE MP3 Click product page they have provided Schematic. You can just use that Schematic and add voice to your projects.
https://www.mikroe.com/click/mp3/
Of course you need a 2 or 3W audio amplifier and Speakers. Adafruit have good modules for amplifiers and they also have Speakers.