> ## Documentation Index
> Fetch the complete documentation index at: https://docs.corti.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Speech to Text

> Updates and improvements to Corti speech to text

Detailed documentation about Speech to Text is available [here](/stt/overview), and supported languages [here](/stt/languages/).

<Update label="2026-05-18" tags={["API", "/transcribe", "/streams"]}>
  ### Raw PCM audio now supported

  Audio processing has been updated so that raw PCM audio can be sent over web socket secure (wss) audio streaming with `/transcribe` and `/streams`. When using raw PCM audio, `audioFormat` must be declared in configuration. See details [here](/stt/audio#raw-audio).
</Update>

<Update label="2026-05-18" tags={["Language Model", "/transcripts"]}>
  ### Infrastructure update for `/transcripts` endpoint to improve speech-to-text performance for audio file processing

  Infrastructure updates to improve performance of audio file processing:

  * Updates to batch sync-to-async audio file processing to ensure consistent latency (RTFx 100)
  * Model updates to reduce risk of hallucinations while improving medical term recall (English, German, French, Danish)
  * Ensure efficient GPU utilization, refine load balancing and partition management (enhance autoscaling of ASR services)

  No client action is necessary to select a specific model version or use the new architecture. See full details on creating transcripts from audio files [here](/api-reference/transcripts/create-transcript).
</Update>

<Update label="2026-05-18" tags={["API", "/languages"]}>
  ### New `/languages` endpoint now available

  New REST endpoint available for clients to programmatically retrieve speech to text languages available per endpoint. See [GET/languages/](/api-reference/languages/list-languages).
</Update>

<Update label="2026-05-18" tags={["Language Model", "/transcribe", "/streams", "/transcripts"]}>
  ### Updated German and French STT models released

  Update STT models for German (`de`, `de-CH`) and French (`fr`) have been released for improved medical term recall and WER performance. This release focused on general terminology recognition, medication names, and punctuation handling.
</Update>

<Update label="2026-05-05" tags={["API", "/transcribe", "/streams"]}>
  ### Audio Health Events

  A new feature for real time audio streaming, **audio health events** are notifications from speech to text system when audio quality may be compromised or problematic. The feature can be enabled with boolean parameter in `transcribe` and `streams` configuration.

  The following two scenarios are supported in this initial release:

  * **Speech Quality Issue Detected** - triggered by background sounds, white noise, or compromised audio.
  * **Long Silence Detected** - defined as 10s of continuous audio without any sound/noise.

  Additional functionality is expected in subsequent releases, as well as ability to define threshold for alerting in the API configuration.

  Learn more about `audioEvents` [here](/stt/audio-events).
</Update>

<Update label="2026-04-21" tags={["API", "/transcribe", "/streams"]}>
  ### Command and formatting updates

  * Added timeout to return formatted text on silence
  * Added non-breaking space before French punctuation characters
  * Added support for square meter (m²) and square centimeter (cm²) units
  * Fixed handling of decimal number format so that negative numbers are supported
  * Security hardening: Improved validation of user-supplied command phrase inputs to prevent malformed values from affecting processing
</Update>

<Update label="2026-04-08" tags={["Language Model", "/transcribe", "/streams"]}>
  ### Updated French speech to text models now available

  French speech to text model (language code `fr`) has been updated for improved medical term recall and conversational, far field audio support.
</Update>

<Update label="2026-04-08" tags={["API", "/streams"]}>
  ### Transcript output formatting now supported on Streams endpoint

  [Formatting](/stt/formatting) is now supported on the `streams` endpoint, with server-defined default values applied automatically. At this time, API configuration of formatting options is not supported for `streams` as it is for `transcribe` endpoint.
</Update>

<Update label="2026-04-08" tags={["API", "/transcribe", "/streams"]}>
  Response messages for configuration errors have been clarified. See details [here](/api-reference/transcribe#5-error-handling) and [here](/api-reference/streams#5-error-handling).
</Update>

<Update label="2026-03-24" tags={["Language Model", "/streams"]}>
  ### Improved diarization now available

  Updates to Corti's Speech to Text models and diarizer, in which reliability and precision for speaker separation and identification have been optimized, have been released.

  See details on this feature [here](/stt/diarization) and configuration recommendations for `streams` and `transcripts` requests [here](/stt/audio#channel-configuration).
</Update>

<Update label="2026-03-23" tags={["API", "/transcribe"]}>
  ### Formatting updates and improvements

  * Add formatting for more units: "g/dL", "cL", "hL", "pL", "mg/L", "mg/kg", "U/mL", "mL/min",
  * Add support for "times two" -> "x2" and "two plus" -> "2+" patterns (1 through 10)
  * Fix handling of German spaced number variations
</Update>

<Update label="2026-03-09" tags={["Language Model", "/transcribe", "/streams"]}>
  ### Next-generation speech recognition models and infrastructure

  New and improved model architecture and infrastructure bring the following actions and benefits:

  | Actions                         | Benefits                                                                               |
  | ------------------------------- | -------------------------------------------------------------------------------------- |
  | **Optimize STT performance**    | Maximize accuracy of transcripts and diarization while minimizing hallucination risk   |
  | **Refine system configuration** | Improve (reduce) latency, augment formatting, and re-introduce interim results feature |
  | **Infrastructure resilience**   | Improve system scalability and GPU resource utilization                                |

  STT models for the following languages have been updated on both `/transcribe` and `/streams` endpoints:

  | Language     | Language Code |
  | ------------ | ------------- |
  | Danish       | `da`          |
  | English      | `en`, `en-GB` |
  | French       | `fr`          |
  | German       | `de`          |
  | Swiss German | `de-CH`       |

  Beyond defining the desired language code in API requests, no client action is necessary to select a specific version of a model. Please [contact us](https://help.corti.app) for support or further information.
</Update>

<Update label="2026-03-09" tags={["API", "/transcribe"]}>
  ### Interim Results now available during real-time dictation for low latency transcript previews

  Use the `interimResults` configuration parameter in `/transcribe` real-time dictation requests to have transcript previews returned from the server at a faster rate than final transcripts.

  See full feature details [here](/stt/interim-results), parameter configuration details [here](/api-reference/transcribe#param-interim-results), and availability by language [here](/stt/transcribe).

  ### Locale-based formatting for dates, times, and numbers

  Dictation formatting can now apply proper styling based on local standards for dates, times, and numbers. Locale is determined based on the `primaryLanguage` defined in the web socket configuration.

  See full formatting details per language [here](/stt/formatting) and parameter configuration details [here](/api-reference/transcribe#param-formatting).

  <Info>Note that legacy date parameter values are still supported by the API; no breaking changes were implemented.</Info>

  ### Dictation formatting improvements

  * Expand units handling
  * Expand <Tooltip tip="Please report incorrectly transcribed acronyms to help@corti.ai">acronym handling</Tooltip>
  * Improve vertebrae formatting: Support for both `letter number` and `letter number letter number` patterns (e.g., "L three" -> "L3" and "L three L four" -> "L3-L4")
  * Improve TNM and cancer stage formatting: Support for `T number N number M number` and `stage number` patterns (e.g., "T two N one M one a" -> "T2 N1 M1a" and "stage two b" -> "Stage IIB")
  * Improve percentage handling: Move handling from `spokenPunctuation` to `formatting` so that percent symbol is only returned when there is a number measurement (e.g., dictation, "What *percent* sure are you question mark *eighty percent*" -> "What *percent* sure are you? *80%*")
  * Expand handling of German dates: Years without spaces (e.g. "zweitausendsechsundswanzig" -> "2026") and new pattern (e.g., include pattern "siebter fünfter neunzehn vierundachtzig" -> "07/05/1984")
  * Expand handling of German units: Units with -n ending (e.g., "Millilitern")
  * Add new default for ordinals, `numerals_above_nine`: Ordinals one through nine are written out (first, second, third) and ten and above are abbreviated (10th, 11th, 12th)
</Update>

<Update label="2026-02-05" tags={["API", "/transcribe"]}>
  ### Dictation formatting improvements

  * Improved support for `en-GB` regional spelling variations
  * Improved support for `de-CH`, `gsw-CH` regional spelling variations
  * Remove extra whitespace observed with degree and percent symbols
  * Updated handling of single digit numbers, now represented as numeral when followed by year/ month/ week/ hour/ day/ minute/ second(s)
  * Updated handling of hyphenated numbers and age dictation
  * Updated handling of "one twenty" (and similar number pattern) dictations
  * Updated handling of Month-Year dictation
  * Fix for an issue that occasionally caused both formatted and unformatted versions of transcript text to be emitted
</Update>

<Update label="2026-01-26" tags={["API", "/transcribe"]}>
  Update to handling of number formatting in Danish.
</Update>

<Update label="2026-01-14" tags={["API", "/transcribe"]}>
  Bug fixes:

  * Update to French formatting for improved number handling
  * Update to Danish formatting for liter abbreviation handling
  * Bug fix for extra whitespace being returned with commands or punctuation
  * Command service performance and reliability improvements
</Update>

<Update label="2025-12-03" tags={["API", "/transcribe"]}>
  ### Dictation Formatting now supported in more languages

  Dictation formatting is now available in **English, German, and French**. There is also limited support in **Danish** with additional improvements in progress.

  See detailed API specification [here](/api-reference/transcribe#param-formatting) and documentation of all available formatting options [here](/stt/formatting).
</Update>

<Update label="2025-11-27" tags={["Language Model", "/transcribe", "/streams"]}>
  ### Improved handling of initialisms in German dictation

  An updated version of the German (`de`) language model was released with improved handling of dictated initialisms: spoken letters, numbers, and abbreviations. Over 800 additional medical abbreviations were introduced to the system, with focused improvement on dental tooth exams, adding support for ICD-10 codes, and ability to have individual letters/numbers returned from the model.
</Update>

<Update label="2025-11-27" tags={["API", "/transcribe", "/streams"]}>
  ### Audio input validation

  Improved server-side validation of streamed audio - if audio does not meet requirements outlined [here](/stt/audio#supported-audio-formats), then a `400 Invalid Audio` error will be returned.
</Update>

<Update label="2025-11-14" tags={["API", "/transcribe", "/streams"]}>
  ### Addition of new web socket event: `flush`

  Provide clients the ability to force clear the audio buffer without closing the connection. In response to a `"type": "flush"` message from the client, the server will return recognized text and/or commands and respond with `"type": "flushed"`, and keep the web socket connection open.

  See more details on `/transcribe` [here](/api-reference/transcribe#flush-the-audio-buffer) and `/streams` [here](/api-reference/streams#flush-the-audio-buffer).
</Update>

<Update label="2025-11-12" tags={["Language Model", "/transcribe", "/streams", "/transcripts"]}>
  ### Update to Swiss German language codes

  There are now two different language codes that may be used for Swiss German use cases:

  * **Swiss German** (language code `gsw-CH`), where dialectical Swiss German is spoken (recommended for AI scribe use cases)
  * **Swiss High German** (language code `de-CH`), where Swiss High German is spoken (recommended for dictation use cases)

  See more details [here](/stt/languages), or please [contact us](https://help.corti.app) if you need further assistant in selecting the best language code.
</Update>

<Update label="2025-10-29" tags={["Language Model", "/transcribe", "/streams"]}>
  ### Updated Danish language model

  Updated Danish (`da`) language model is now available for dictation (`/transcribe`) and ambient (`/streams`) use cases. The language is rated as `premier` tier as over 158,000 medical terms were included in the training and validation data sets.
</Update>

<Update label="2025-10-29" tags={["API", "/transcribe"]}>
  Bug fixes:

  * Fixed an issue that prevented `automaticPunctuation` parameter from working as expected. Furthermore, `spokenPunctuation` and `automaticPunctuation` are mutually exclusive: Only one of these parameters should be set to `true` in a given `/transcribe` configuration, and if both settings are present and set to true, then `spokenPunctuation` will take precedence. See more detail [here](/stt/punctuation).
</Update>

<Update label="2025-10-13" tags={["Language Model", "/transcribe", "/streams"]}>
  ### Updated French language model

  Updated French (`fr`) language model is now available for dictation (`/transcribe`) and ambient (`/streams`) use cases. The language is rated as `premier` since over 170,000 medical terms were included in the training and validation data sets.
</Update>

<Update label="2025-10-03" tags={["Language Model", "/transcribe"]}>
  ### Dictation now supported in Dutch and Norwegian

  Norwegian (`no`) and Dutch (`nl`) are now available for use on the `/transcribe` endpoint for dictation use cases. As a result they have been moved to the `enhanced` language tier. Additionally, Hungarian (`hu`) medical terminology has been expanded and improved.

  See more information about supported functionality for dictation [here](/stt/transcribe) and language tiers [here](/stt/languages).
</Update>

<Update label="2025-09-29" tags={["Language Model", "/transcripts"]}>
  Feature limitation:

  * Some of the recent `/transcripts` endpoint language model updates (`de`, `en`, `en-GB`, `fr`) have been rolled back so that performance of asynchronous audio file processing can be improved. Infrastructure updates are underway to improve model performance.
  * Speech-to-text accuracy from `/transcripts` asynchronous audio file processing may be degraded as compared to real-time audio processing via the `/streams` and `/transcribe` APIs, which are not impacted by this issue.
</Update>

<Update label="2025-09-24" tags={["Language Model", "/transcribe", "/streams", "/transcripts"]}>
  ### Updated English language model

  Updated English (`en`) language model is now available for dictation (`/transcribe`), ambient (`/streams`), and transcription (`/transcripts`) use cases. This version is rated as `premier` tier as over 170,000 medical terms were included in the training and validation data sets.
</Update>

<Update label="2025-09-24" tags={["API", "/transcribe", "/streams", "/transcripts"]}>
  ### Improved transcoding support in speech-to-text APIs

  Update to both streaming and asynchronous audio file processing so that **transcoding is supported**. Previously audio files were required to conform to 16-bit, 16kHz formatting. Now, assuming proper file types are used, any precision and sample rate are accepted. See more details [here](/stt/audio).
</Update>

<Update label="2025-09-24" tags={["API", "/transcripts"]}>
  Parameter deprecation:

  * Definition of the parameter `modelName` is no longer required in `/transcripts` API requests. The latest and greatest model available per language will be applied automatically.
  * If the argument is included in the request, then it will be ignored. If the configuration is otherwise valid, then the request will process as expected. See full specification [here](/api-reference/transcripts/create-transcript).
</Update>

<Update label="2025-09-24" tags={["API", "/transcribe"]}>
  Feature limitation:

  * The interim (preview) results feature of the `/transcribe` API is not performing as expected. As a result, it is being disabled for most languages to prevent issues with speech-to-text latency and accuracy.
  * If the `interimResults` parameter is included in the request for a language that does not support this functionality it will be ignored and, so long as the request is otherwise valid, the configuration will be accepted.
</Update>

<Update label="2025-08-21" tags={["Language Model", "/streams"]}>
  ### Conversational transcripts now supported in Arabic

  Arabic (language code `ar`) is now available for ambient documentation workflow - Capture conversations spoken in Arabic via the `/streams` API.
</Update>

<Update label="2025-08-06" tags={["API", "/transcribe"]}>
  ### New dictation functionality available: `Formatting`

  New dictation functionality available: **Formatting**. Take control over how dates, time, units, and numbers should be transcribed in the streaming speech to text output.

  See detailed API specification [here](/api-reference/transcribe#param-formatting) and documentation of all available formatting options [here](/stt/formatting).
</Update>

<Update label="2025-07-28" tags={["Language Model", "/transcribe", "/streams", "/transcripts"]}>
  ### Updated German language model

  Updated German (de) language model is now available for dictation (`/transcribe`), ambient (`/streams`), and transcription (`/transcripts`) use cases. This version is rated `premier` tier as over 150,000 medical terms were included in the training and validation data sets.
</Update>

<Update label="2025-07-18" tags={["Language Model", "/transcribe"]}>
  ### Dictation now supported in Hungarian

  Hungarian (hu) Enhanced language model is now available for dictation (`/transcribe`).
</Update>

<Update label="2025-07-04" tags={["Language Model", "/transcribe"]}>
  Swedish (sv) Enhanced language model is now available for dictation (`/transcribe`).
</Update>

<Update label="2025-06-25" tags={["Language Model", "/streams", "/transcripts"]}>
  Updated Norwegian (no) and Swedish (sv) Base language models are now available for ambient documentation (`/streams`) and transcription (`/transcripts`) workflows.
</Update>

<Update label="2025-05-30" tags={["Language Model", "/transcribe"]}>
  Danish (da), German (de), and French (fr) Enhanced language models now available for dictation (`/transcribe`) workflows.
</Update>

<Update label="2025-04-09">
  New API endpoint, `/transcribe` now available! Use this endpoint for stateless, real-time streaming dictation workflows. See more details [here](/api-reference/transcribe/) in the API reference and [here](/stt/dictation-web/) for access to the Corti Dictation Web Component. <br />
</Update>

<Update label="2025-03-28" tags={["Language Model", "/streams"]}>
  Swiss German (de-CH) Enhanced language model now available for ambient documentation (`/streams`) workflows.
</Update>

<Update label="2025-03-11" tags={["Language Model", "/streams"]}>
  French (fr) Enhanced language model now available for ambient documentation (`/streams`) workflows.
</Update>

<Update label="2025-03-08" tags={["API", "Language Model", "/transcribe", "/streams", "/transcripts"]}>
  Introducing a new tier system for defining functionality and performance of speech to text language models. Read more about it [here](/stt/languages/).
</Update>

<Update label="2025-02-25" tags={["Language Model", "/streams", "/transcripts"]}>
  Updated German (de) and Swiss German (de-CH) language models available.
</Update>

<Update label="2025-02-11" tags={["Language Model", "/streams", "/transcripts"]}>
  Updated Danish (da) and Swedish (sv) language models available.
</Update>

<Update label="2025-01-28" tags={["API", "Language Model", "/streams", "/transcripts"]}>
  Announcing the launch of Corti AI Platform. Read more about it [here](https://www.corti.ai/).

  The following languages are supported by Corti speech to text: English (en for US English, and en-GB for UK English), Danish (da), German (de), Swiss German (de-CH), French (fr), Swedish (sv), Spanish (es), Norwegian (nl), Dutch (no), Italian (it), and Portuguese (pt)
</Update>