AssemblyAI Release Notes

We've added support for multichannel speaker diarization with pre-recorded transcription, allowing you to identify individual speakers across multiple audio channels in a single API request.

This unlocks accurate transcription for complex audio scenarios like hybrid meetings, call center recordings with supervisor monitoring, or podcast recordings with multiple mics. Speaker labels are formatted as 1A, 1B, 2A, 2B, where the first digit indicates the channel and the letter identifies unique speakers within that channel. For example, in a meeting where Channel 1 captures an in-room conversation between two people and Channel 2 captures a remote participant, you'll get clear attribution for all three speakers even though Channel 1 contains multiple talkers.

How to use it

• Set both multichannel=true and speaker_labels=true in your transcription request—no other changes needed
• Available now for all Universal customers across all plan tiers
• View documentation

Universal delivers industry-leading accuracy with advanced features like multichannel support and speaker diarization, giving you the precision and flexibility needed to build production-grade voice AI applications.‍

We've updated how uploaded audio files are deleted when you delete a transcript, giving you immediate control over your data.

Previously, when you made a DELETE request to remove a transcript, the associated uploaded file would remain in storage for up to 24 hours before automatic deletion. Now, uploaded files are immediately deleted alongside the transcript when you make a DELETE request, ensuring your data is removed from our systems right away.

This change applies specifically to files uploaded via the /upload endpoint. If you're reusing upload URLs across multiple transcription requests, note that deleting one transcript will now immediately invalidate that upload URL for any subsequent requests.

How it works

• When you send a DELETE request to remove a transcript, any file uploaded via /upload and associated with that transcript is now deleted immediately
• This applies to all customers using the /upload endpoint across all plans
• If you need to transcribe the same file multiple times, upload it separately for each request or retain the original file on your end

AssemblyAI's APIs are built with security and data privacy as core principles. Our speech-to-text and audio intelligence models process your data with enterprise-grade security, and now with even more granular control over data retention.

Learn more about our data security practices
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Google's newest Gemini 3 Flash Preview model is live in the LLM Gateway.

This model delivers faster inference speeds with improved reasoning capabilities compared to previous Flash versions. Gemini 3 Flash Preview excels at high-throughput applications requiring quick response times—like real-time customer support agents, content moderation, and rapid document processing—while maintaining strong accuracy on complex queries that would have required slower, more expensive models.

For more information, check out our docs here.

Keyterm prompting is now in production for multilingual streaming

Keyterm prompting is now in production for multilingual streaming, giving developers the ability to improve accuracy for target words in real-time transcription. This enhancement is live for all users across the Universal-Streaming platform.

Keyterm prompting enables developers to prioritize specific terminology in transcription results, which is particularly valuable for conversational AI and voice agent use cases where domain-specific accuracy matters. By specifying keywords relevant to your application, you'll see improved recognition of critical terms that might otherwise be misheard or misinterpreted.

To use Keyterm prompting with Universal-Streaming Multilingual, include a list of keyterms in your connection parameters:

CONNECTION_PARAMS = {
  "sample_rate" : 16000 ,
  "speech_model" : "universal-streaming-multilingual" ,
  "keyterms_prompt" : json.dumps([
    "Keanu Reeves" , "AssemblyAI" , "Universal-2"
  ])
}

Expanding Keyterm prompting to Universal-Multilingual Streaming

Expanding Keyterm prompting to Universal-Multilingual Streaming reinforces our commitment to giving developers precise control over recognition results for specialized vocabularies.

Learn more in our docs.

Improvements

We've improved hallucination detection and reduction across Universal-Multilingual Streaming transcription, resulting in fewer false outputs while maintaining minimal latency impact. This improvement is live for all users.

Lower hallucination rates mean more reliable transcription results out of the box, especially in edge cases where model confidence is uncertain. You'll see more accurate, trustworthy outputs without needing to modify existing implementations

This improvement is automatic and applies to all new Streaming sessions.

Security controls for pre-recorded file transcription

We've tightened security controls on pre-recorded file transcription by scoping access to uploaded files within the same project that uploaded them.

Previously, API tokens could transcribe files across projects. Now, tokens must belong to the same project that originally uploaded the file to transcribe it. This strengthens your security posture and prevents unintended cross-project access to sensitive audio files.

This security enhancement reflects our commitment to protecting your data and giving you granular control over who can access transcriptions within your organization.

Self-Hosted Streaming v0.20: License Management Now Available

Self-Hosted Streaming v0.20 now includes built-in license generation and validation, giving enterprises complete control over deployment security and usage tracking. Organizations can manage their speech AI infrastructure with the same compliance controls they expect from enterprise software.

The new licensing system enables IT teams to track deployment usage, enforce security policies, and maintain audit trails—critical for regulated industries like healthcare and financial services. License validation happens at startup and can be configured for periodic checks to ensure continuous compliance.

Available now for all AssemblyAI Self-Hosted Streaming customers.
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Contact your account team to generate licenses for your deployments.
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Multi-Region Streaming: US-East-1 Now Live

AssemblyAI's Streaming API is now available in us-east-1 , providing regional redundancy and expanded compute capacity for production workloads. The infrastructure update reduces single-region dependency and prepares the platform for upcoming EU deployment.

Multi-region availability means contact centers and live captioning applications can maintain service continuity during regional incidents while accessing additional compute capacity for peak usage periods. The architecture changes also enable faster rollout of new regions based on customer demand.

Available immediately across all AssemblyAI's Streaming API plans.
Traffic is automatically routed to the optimal region based on latency and capacity.

Try AssemblyAI’s Streaming API now or view regional availability .
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Inactivity Timeout Controls for Streaming Sessions

AssemlyAI’s Streaming API now supports configurable inactivity_timeout parameters, giving developers precise control over session duration management. Applications can extend timeout periods for long-running sessions or reduce them to optimize connection costs.

The feature enables voice agents and live transcription systems to automatically close idle connections without manual intervention. Contact centers can reduce costs on silent periods while ensuring active calls stay connected. Voice agent developers can keep sessions open longer during natural conversation pauses without manual keep-alive logic.

Available now for all AssemblyAI Streaming customers.
Set the inactivity_timeout parameter (in seconds) when initializing your connection.

• Set inactivity_timeout in your connection parameters
• Values range from 5 to 3600 seconds
• Default timeout remains 30 seconds if not specified
• Available across all pricing tiers

View our documentation to learn more.
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We've released a new version of our English Streaming model with significant improvements across the board.

Across the board:

• 88% better accuracy on short utterances and repeating commands/numbers
• 12% faster emission latency
• 7% faster time to complete transcript
• 4% better accuracy on prompted keyterms
• 3% better accuracy on accented speech

Performance gains

• 88% better accuracy on short utterances and repeating commands/numbers
• 12% faster emission latency
• 7% faster time to complete transcript
• 4% better accuracy on prompted keyterms
• 3% better accuracy on accented speech

New features

• Language detection for utterances (Multilingual model only) – Get language output for each utterance to feed downstream processes like LLMs
• Dynamic keyterms prompting – Update your keyterms list mid-stream to improve accuracy on context you discover during the conversation