Soniox vs OpenAI
for Bulgarian speech-to-text
Higher accuracy, richer real-time features, and lower cost for Bulgarian transcription.
Developers choose Soniox for real-time, real world Bulgarian fluency
Bulgarian is spoken by 8 million people worldwide — primarily in Bulgaria, with speakers around the world. Soniox delivers production-ready transcription and translation for Bulgarian, handling regional accents, code-switching, and real-world audio conditions. OpenAI lists Bulgarian as supported, but benchmark results show far higher error rates compared to Soniox.
If you need higher real-world accuracy for Bulgarian, live streaming features built for apps, and lower cost at scale, Soniox is the better fit. OpenAI's new Realtime API combines transcription and voice output in one API, designed for full voice agents. But it costs more for lower accuracy than Soniox, and lacks diarization, supports only one-way translation into English, and doesn't provide the structured metadata (timestamps, confidence, manual finalize) that developers rely on.
Higher accuracy in Bulgarian, and 60+ languages
Bulgarian Word Error Rate 5.6% for Soniox vs 17.2% for OpenAI (lower is better).
Live streaming features, out of the box
Real-time token streaming, diarization, and Bulgarian translation in the same stream.
Lower cost, higher value
Pay up to 10x less than OpenAI, which charges more and requires multiple endpoints.
Helping startups and enterprises ship real world voice apps
See the difference for yourself
Don't just take our word for it. Run the same Bulgarian audio through Soniox and OpenAI in real time and compare live results, side by side.
This demo isn't pre-recorded. It makes real API calls to OpenAI and Soniox in real time, with each service tuned for its best performance. The framework is open source, so you can inspect or run it yourself.
SONIOX VS OPENAI AT A GLANCE
The benchmarks back it up
In a 2025 study across 60 languages and real-world YouTube audio, Soniox reached 5.6% WER in Bulgarian vs 17.2% for OpenAI.
View the full benchmark report| Feature | Sonioxstt-rt-v3 | OpenAIgpt-4o-transcribe |
|---|---|---|
| open_in_newSingle Multilingual Model | check | check |
| open_in_newLanguage Hints | check | close |
| open_in_newLanguage Identification | check | close |
| open_in_newSpeaker Diarization | check | close |
| open_in_newCustomization | check | check |
| open_in_newTimestamps | check | close |
| open_in_newConfidence Scores | check | check |
| open_in_newTranslation One Way | check | check |
| open_in_newTranslation Two Way | check | close |
| open_in_newEndpoint Detection | check | close |
| open_in_newManual Finalization | check | close |
“It just gets the words right — any language, any accent, any context. That’s what accuracy is supposed to look like.”
Tony Wang,
Cofounder & Chief Revenue Officer at Agora
One call. All features. No compromises.
One API, global by default.
Soniox supports 60+ languages with production-ready accuracy in a single model. One call works for 8 million Bulgarian speakers.
Unlike OpenAI, which splits transcription, translation, and streaming across multiple APIs, and struggles in major languages like Hindi and Mandarin.
Streaming in Bulgarian that feels live.
Token-by-token updates appear in milliseconds and stabilize as words finish. Captions don't lag, and assistants respond in sync.
OpenAI's Realtime API supports live transcription, but without diarization, multi-language translation, or transcript metadata. Soniox includes all of these in one stream.
Designed for real-world Bulgarian speech.
Soniox doesn't stop at transcription. It translates speech in real time, handling accents, slang, overlap, and language shifts with aplomb.
OpenAI only supports one-way translation into English, with no in-stream two-way translation or speaker handling.
Ship faster, with fewer moving parts.
Instead of patching together multiple vendors or APIs, Soniox gives you transcription, translation, and diarization in one call.
With OpenAI, you'll be managing separate endpoints and extra tooling.
Pay 2-10x less than OpenAI
With Soniox, all features are included in one price: transcription, streaming, diarization, translation, and 60+ languages. OpenAI charges more and splits features across different endpoints.
Effective hourly cost
(typical speech)
Soniox
~$0.10/hour (async)
~$0.12/hour (streaming)
OpenAI
~$0.38–$1.15/hour
Soniox and OpenAI Whisper are shown as effective $/hour. OpenAI Realtime API is billed per token. Estimates assume typical conversational speech.
Takeaway
Soniox costs 2–10x less than OpenAI. At scale, enterprises save $200K–$1M+ over 3 years, while getting higher accuracy and richer features.
- What about OpenAI's new Realtime API?
OpenAI now charges per token: $32 per million input tokens, $64 per million output tokens
Works out to ~$0.38/hour for transcription or ~$1.15/hour with audio output.
Soniox remains ~$0.10–$0.12/hour, with all features included.
Fluent at any speed
Watch Soniox keep up with fast speech in any language
Chinese to English in real time with SONIOX
Very fast speaking Spanish translated in real time in English with SONIOX!
Real time translation from Japanese to English
Real-Time Translation Demo | From German to English with SONIOX
French speech to Text | Leslie Talks About Monster eating a Cake
Russian to English with SONIOX
Speaking Super Fast in Italian – Soniox still translated every word into English
Korean to English in real time with SONIOX
Real-Time from Slovenian to English with SONIOX
Valeria Juri Reads Ukrainian Poem “Мовчати” | Live English Translation by Soniox
Frequently asked questions about Soniox vs OpenAI
1.How accurate is Soniox vs OpenAI for Bulgarian?arrow_downward
2.Can Soniox handle regional Bulgarian accents?arrow_downward
3.Is Soniox cheaper than OpenAI?arrow_downward
Yes. Soniox is billed per token, which works out to about $0.10/hour async or $0.12/hour streaming for typical speech (Soniox pricing).
OpenAI's costs are higher:
- $0.18/hour for gpt-4o-mini-transcribe
- $0.36/hour for gpt-4o-transcribe (OpenAI pricing).
- ~$0.38–$1.15/hour for the new Realtime API, depending on whether you generate audio output (OpenAI Realtime)
That means Soniox is typically 2–10x less expensive, while also including features like real-time diarization, translation, and structured transcript metadata by default.
4.Does Soniox support more languages than OpenAI Whisper?arrow_downward
Soniox supports 60+ languages with production-ready accuracy and can translate between any pair of supported languages, including Bulgarian. OpenAI's Whisper was trained on ~99 languages, but production quality is strong only in a few (like English and Spanish). Many others, including widely spoken languages such as Hindi and Mandarin, are effectively unusable for real-world apps.
With Soniox, one API automatically works for 8 billion people worldwide.
5.Does OpenAI include diarization or translation in real time?arrow_downward
6.What makes Soniox streaming different from OpenAI?arrow_downward
7.Do I need multiple APIs with OpenAI?arrow_downward
8.Are Soniox benchmarks public?arrow_downward
Soniox surpasses OpenAI in any language
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