Languages

Spelo is built on OpenAI’s Realtime API, which natively supports multilingual input and output. You set the primary language in your site config; the AI can still understand and respond in other languages when visitors switch mid-conversation.

Supported languages

The Realtime API works well in these languages. The list grows as OpenAI improves the model.

Language	Code	Quality
English	`en`	Excellent
Spanish	`es`	Excellent
French	`fr`	Excellent
German	`de`	Excellent
Italian	`it`	Excellent
Portuguese (BR)	`pt`	Excellent
Dutch	`nl`	Very good
Japanese	`ja`	Very good
Korean	`ko`	Very good
Mandarin Chinese	`zh`	Good
Hindi	`hi`	Good
Arabic	`ar`	Good
Turkish	`tr`	Good
Polish	`pl`	Good
Russian	`ru`	Good
Swedish, Norwegian, Danish, Finnish	`sv`, `no`, `da`, `fi`	Good

“Good” means: reliable transcription and coherent responses, occasional mispronunciations. “Excellent” means: indistinguishable from a native speaker in casual testing.

Configuration

Dashboard → Voice → Language → pick one. This sets:

The language hint passed to OpenAI at session start
The default greeting language
The formatting of dates and numbers (“$1,234.56” vs “1.234,56 €“)

Mixed-language sessions

Even with English as primary, visitors can speak Spanish and the AI will respond in Spanish. It’s a mid-session switch, triggered by the model itself.

If you want strict single-language, add to your custom instructions:

Always respond in French, regardless of the visitor's language.
If the visitor speaks English, acknowledge in French and continue in French.

Voice + language compatibility

All six OpenAI voices (alloy, echo, fable, onyx, nova, shimmer) support every listed language. Accent varies:

alloy, echo, onyx — sound more neutral / North American
fable — slight British English inflection
nova, shimmer — sound more North American

For non-English sites, test each voice. Some sound more native than others depending on the target language.

Pronunciations across languages

The pronunciation dictionary works in every language. Write the say_as in the target language’s phonetics:

word	say_as (for French audience)
`Hodos360`	`HO-doze trois-cent-soixante`
`Wi-Fi`	`wee-fee`

Data in another language

If your data is in one language but you want the AI to respond in another (e.g. English product descriptions but Spanish-speaking visitors), add to custom instructions:

Our product data is in English. When speaking Spanish, translate product
names and descriptions naturally as you read them. Keep SKU codes in their
original English form.

The model handles this well for mainstream product data.

Transcription accuracy

OpenAI’s Realtime uses Whisper under the hood for transcription. Whisper excels on clean audio; noisy or fast speech can cause errors. If you run multi-language sites in acoustically noisy environments (car dealerships, coffee shops), expect slightly worse transcription.

Not yet supported

Simultaneous multi-language interfaces (one voice + caption in another language) — not yet. Pick one language per site.
Sign language — no plans.
Language auto-detection at first utterance — the model does this decently but we recommend setting language explicitly for consistency.