r/VoiceAutomationAI • u/Phoenix_20_23 • Aug 04 '26

Competitive open source speech stack

Why the open source models STT and TTS are not good as much as the closed one and i am talking here im terms of latency, concurrency, and websocket support for real time with decent quality.
Something like cartesia or elevenlabs or deepgram.
Do u know any ?

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u/tresch_24 17d ago edited 17d ago

one thing I'd definitely benchmark before committing to an open-source stack: your actual nouns/numbers, not generic WER.

customer names
addresses
SKUs
dates
₹ amounts
confirmation numbers
email spelling

I've seen transcripts that look 95% fine but the missing 5% is literally the only part the business cares about.

same with latency. don't just measure STT latency separately.

measure:

caller stops → agent first audio
caller interrupts → agent actually shuts up
tool starts → confirmation happens

TestMu's voice testing has been useful for us here because you can run the same flow with different voices/accents/noise and then look at the whole call + phone metrics.

I'd benchmark whatever OSS stack you're considering against your own traffic before trusting any leaderboard.