Android: Generate audio file containing random numbers to be played through earspeaker

I'm working on a project where I need to do the following:

• Generate 4 random numbers (each number is between 1-9)
• Generate an audio file with the generated numbers "pronounced" by a "voice"
• Ask the user to input those numbers using the phone's keypad
• Match the played numbers with user input and determine if they match

The only way I can think of to go about this is the following:

• Record individual numbers in separate audio files(1, 2, 3, etc, each in a separate audio file)
• Generate 4 random numbers (each number is between 1-9)
• Compile the corresponding numbers in one audio file (using the individual audio files of each number)
• Ask the user to input those numbers using the phone's keypad
• Match the played numbers with user input and determine if they match

Now, this method didn't set right with me as I think there's a better way to go about this. Can I achieve the same thing without having to record individual numbers in separate audio files and then recompile those files into one audio file depending on the random numbers generated programmatically?