One of the top requested features for my daily Chinese vocab app was the ability to hear the audio pronunciation for words. To generate audio files from text in bulk, I built a Step Functions workflow that uses the AWS text to speech service, Polly. The workflow generates an audio file for a vocabulary word, saves the audio file to S3, and updates the DynamoDB record for the vocab word with the S3 file location. I'm also speeding up the process of generating audio files for thousands of vocabulary words by processing files in parallel. â