# Detecting Speech Interference When scoring pronunciation, the audio submitted to the Speechace API should contain only the speech the user intends to be assessed — the words in the `text` parameter. In real-world conditions, however, recordings often contain additional speech beyond what was expected: a speaker in the background, the user continuing to speak after the expected text, or another person's voice overlapping with the user's. This additional speech is called **interference**. The Speechace API can detect and measure it, returning an `interference_ratio` that tells you how much of the audio contains speech that competes with the intended text for alignment and scoring. ## Interference vs. General Noise It is important to distinguish between **interference** and general background noise: * **Background noise** — non-speech sounds such as music, traffic, typing, or ambient room noise. These affect recording quality but do not compete directly with the alignment and scoring of the expected words. * **Speech interference** — *speech* that is present in the audio beyond what the `text` parameter describes. This directly competes with the scoring engine when it attempts to align and score what was spoken. Common sources include: * A second speaker in the room talking over the user * The user continuing to speak additional sentences after the expected text ends * A TV, podcast, or voice recording playing in the background Speechace's interference detection is specifically focused on **competing speech**, not general noise. ## How to Request Interference Metrics Pass `include_interference_metrics = 1` as a form body parameter in your [Score Text/Pronunciation](https://api-docs.speechace.com/api-reference/score-text-pronunciation) request: ```bash curl --location -g 'https://api.speechace.co/api/scoring/text/v9/json?key={{speechacekey}}&dialect=en-us' \ --form 'text="Some parents admire famous athletes as strong role models."' \ --form 'user_audio_file=@"recording.wav"' \ --form 'include_interference_metrics=1' ``` Without this parameter, `interference_ratio` is not returned in the response. ## Response When `include_interference_metrics = 1` is set, the `text_score` object in the response includes an `interference_ratio` field: ```json { "status": "success", "text_score": { "text": "Some parents admire famous athletes as strong role models.", "interference_ratio": 2.7, "word_score_list": [ ... ], "speechace_score": { "pronunciation": 85 } } } ``` ## Interpreting interference\_ratio The `interference_ratio` is a numeric value that increases with the severity of detected speech interference. Use the following bands as a guide:
interference_ratioLevelInterpretation
0NoneNo excess speech detected. The audio closely matches the expected text with no competing speech.
0 – 1LowA small amount of extra speech is present — for example, a brief word spoken before or after the intended text. Scoring results are reliable.
2 – 3MidA moderate amount of competing speech is detected. Scoring may be affected; consider surfacing a caution to the user.
3+HighSignificant speech interference is present. Scoring reliability is reduced. The user should be prompted to retry in a quieter environment.
## Using interference\_ratio in Your Application The `interference_ratio` gives your application actionable signal about recording conditions. Here are the recommended patterns: Warn about reduced scoring reliability ``` if interference_ratio >= 2: show_warning("Your recording contained background speech. " "Your score may not fully reflect your pronunciation.") ``` Guide users to retry in a quieter environment ``` if interference_ratio >= 3: show_prompt("We detected other voices in your recording. " "Please try again somewhere quieter for a more accurate score.") ``` Apply reduced weighting to high-interference items ``` if interference_ratio >= 3: flag_for_review(item_id, reason="high_interference") # Exclude from final score calculation or prompt a re-attempt ``` ## Notes
Additional notes about interference metrics * `interference_ratio` is only present in the response when `include_interference_metrics = 1` is explicitly passed. It is not returned by default. * Interference detection applies to the Score Text/Pronunciation endpoint. See the [API Reference](https://api-docs.speechace.com/guides-on-common-topics/broken-reference) for the full parameter list.