Thank you so much for the comment. Text-to-speech costs $16.00 USD / 1 million characters[1]. So if an article has 5,000 characters, it costs 0.08 USD. If you put 20 articles, it costs 1.6USD. And current my assumption is most of the articles contains more than 5,000 characters. [1] https://cloud.google.com/text-to-speech/pricing