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

# Comparative Similarity

> Evaluate the similarity between two audio samples and a reference audio

## Intro

The Comparative Similarity (CSMOS) evaluation is designed to assess which of two audio samples is more similar to a reference audio. This evaluation is particularly useful in scenarios where the goal is to match or mimic a reference audio, such as in voice cloning or audio restoration tasks.

* **Objective**: Determine the similarity of two audio samples to a reference audio.
* **Use Case**: Ideal for applications requiring audio matching or quality assessment against a standard.
* **Type**: `CSMOS` in the SDK.

![CSMOS](https://static-public.podonos.com/sdk/usecase/comparative_similarity.png)

## Example

<Steps>
  <Step title="Initialize the Client">
    Begin by initializing the Podonos client with your API key.

    ```python theme={null}
    import podonos

    client = podonos.init("<API_KEY>")
    ```
  </Step>

  <Step title="Create the Evaluator">
    Set up the evaluator for a CSMOS evaluation.

    ```python theme={null}
    evaluator = client.create_evaluator(
        name="Comparative Similarity Test",
        desc="Evaluate similarity of audio samples to a reference",
        type="CSMOS"
    )
    ```

    <Warning>
      `CSMOS` is not allowed by the `create_evaluator_from_template_json` method
    </Warning>
  </Step>

  <Step title="Add Files for Evaluation">
    Add two audio samples and one reference audio. The reference file must be specified with `is_ref=True`.

    ```python theme={null}
    from podonos import File

    evaluator.add_files(
        file0=File(path="audio_sample1.wav", model_tag="Sample 1", tags=["test"], is_ref=False),
        file1=File(path="audio_sample2.wav", model_tag="Sample 2", tags=["test"], is_ref=False),
        file2=File(path="reference_audio.wav", model_tag="Reference", tags=["reference"], is_ref=True)
    )
    ```

    * **File Order**: Ensure the reference file is the third file in the `add_files` method.
  </Step>

  <Step title="Finalize the Evaluation">
    Close the evaluator to complete the setup.

    ```python theme={null}
    evaluator.close()
    ```
  </Step>
</Steps>

## Key Considerations

* **File Configuration**: The reference file must be clearly marked with `is_ref=True` and should be the last file in the `add_files` method.
* **Evaluation Logic**: The CSMOS evaluation logic will compare the two audio samples against the reference to determine which is more similar.
* **Applications**: Useful for tasks like voice cloning, audio restoration, and quality assurance where matching a reference is critical.

## Use Case

Consider a scenario where you are developing a new speech synthesis model and want to evaluate how closely the generated audio matches a reference recording. Using CSMOS, you can objectively assess which version of your model produces audio that is more similar to the desired reference.