Combine multiple base64 audio strings into into one in node.js

I want to combine six base64 strings (which I get from getAllAudioBase64 method in the google-tts-api npm package) into one in node.js. I have tried multiple solutions like this one, but none of them seem to work. Is there a way to combine them directly instead of converting them into mp3 and then using ffmpeg to combine them?

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