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Phase 15

STT

~3 min read

Concept & How It Works

    Why Does It Exist?

    Voice is the most natural interface for hands-free scenarios — driving, cooking, customer support calls. STT bridges human speech and LLM text processing.

    Real-World Analogy

    STT is a court stenographer — they listen to spoken words and type them out in real time for the record.
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    Visual Workflows

    What is STT?

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    Example

    Scenario

    User speaks into mobile app → streaming STT converts to text in 300ms → text sent to support agent → agent responds → TTS plays answer.

    Solution

    In Voice & Multimodal Agents, apply STT to this scenario: User speaks into mobile app → streaming STT converts to text in 300ms → text sent to support agent → agent responds → TTS plays answer. Identify the inputs, run the technique, validate the output, and note one thing you would monitor in production.

    Practice Task

    Do this before moving to the next module — reading alone is not enough.

    Open the Code Walkthrough below and run it locally. Change one parameter related to STT (e.g. model, temperature, top_k, or tool name), observe the difference in output, and write 2–3 sentences explaining what changed.

    Code Walkthrough

    Highlighted lines show where STT happens in the code.

    STT
    1from openai import OpenAI  # import dependencies2
    3client = OpenAI()  # create API client4
    5def transcribe(audio_file_path: str) -> str:  # define a reusable function6    with open(audio_file_path, "rb") as f:7        transcript = client.audio.transcriptions.create(  # call the API8            model="whisper-1",9            file=f,10            response_format="text",11        )12    return transcript  # return the result

    Commands to Remember

    Commands to Remember

    • pip install openai # vision, audio, and TTS APIs
    • pip install pypdf # PDF ingestion for document agents

    Common Mistakes

    • Treating STT as a black box without evaluation
    • Ignoring cost and latency in production
    • Skipping error handling for stt

    Cheat Sheet

    Quick recap — the most important points from this module.

    Cheat Sheet

    quick ref
    • STT
    • WER
    • Whisper
    • Streaming STT