Automatic Language Detection | AssemblyAI

Supported languages

Global Englishen

Australian Englishen_au

British Englishen_uk

US Englishen_us

Spanishes

Frenchfr

Germande

Italianit

Portuguesept

Dutchnl

Hindihi

Japaneseja

Chinesezh

Finnishfi

Koreanko

Polishpl

Russianru

Turkishtr

Ukrainianuk

Vietnamesevi

Afrikaansaf

Albaniansq

Amharicam

Arabicar

Armenianhy

Assameseas

Azerbaijaniaz

Bashkirba

Basqueeu

Belarusianbe

Bengalibn

Bosnianbs

Bretonbr

Bulgarianbg

Burmesemy

Catalanca

Croatianhr

Czechcs

Danishda

Estonianet

Faroesefo

Galiciangl

Georgianka

Greekel

Gujaratigu

Haitianht

Hausaha

Hawaiianhaw

Hebrewhe

Hungarianhu

Icelandicis

Indonesianid

Javanesejw

Kannadakn

Kazakhkk

Khmerkm

Laolo

Latinla

Latvianlv

Lingalaln

Lithuanianlt

Luxembourgishlb

Macedonianmk

Malagasymg

Malayms

Malayalamml

Maltesemt

Maorimi

Marathimr

Mongolianmn

Nepaline

Norwegianno

Norwegian Nynorsknn

Occitanoc

Panjabipa

Pashtops

Persianfa

Romanianro

Sanskritsa

Serbiansr

Shonasn

Sindhisd

Sinhalasi

Slovaksk

Sloveniansl

Somaliso

Sundanesesu

Swahilisw

Swedishsv

Tagalogtl

Tajiktg

Tamilta

Tatartt

Telugute

Thaith

Tibetanbo

Turkmentk

Urduur

Uzbekuz

Welshcy

Yiddishyi

Yorubayo

Supported models

Universaluniversal

Supported regions

US & EU

Identify the dominant language spoken in an audio file and use it during the transcription. Enable it to detect any of the supported languages.

To reliably identify the dominant language, a file must contain at least 15 seconds of spoken audio. Results will be improved if there is at least 15-90 seconds of spoken audio in the file.

1 import assemblyai as aai
2 
3 aai.settings.api_key = "<YOUR_API_KEY>"
4 
5 # audio_file = "./local_file.mp3"
6 audio_file = "https://assembly.ai/wildfires.mp3"
7 
8 config = aai.TranscriptionConfig(language_detection=True)
9 
10 transcript = aai.Transcriber(config=config).transcribe(audio_file)
11 
12 print(transcript.text)
13 print(transcript.json_response["language_code"])

Set a list of expected languages

If you’re confident the audio is in one of a few languages, provide that list via language_detection_options.expected_languages. Detection is restricted to these candidates and the model will choose the language with the highest confidence from this list. This can eliminate scenarios where Automatic Language Detection selects an unexpected language for transcription.

Use our language codes (e.g., "en", "es", "fr").
If expected_languages is not specified, it is set to ["all"] by default.

1 import assemblyai as aai
2 
3 aai.settings.api_key = "<YOUR_API_KEY>"
4 
5 # audio_file = "./local_file.mp3"
6 audio_file = "https://assembly.ai/wildfires.mp3"
7 
8 options = aai.LanguageDetectionOptions(
9     expected_languages=["en", "es", "fr", "de"],
10     fallback_language="auto"
11 )
12 
13 config = aai.TranscriptionConfig(language_detection=True, language_detection_options=options)
14 
15 transcript = aai.Transcriber(config=config).transcribe(audio_file)
16 
17 print(transcript.text)
18 print(transcript.json_response["language_code"])

Choose a fallback language

Control what language transcription should fall back to when detection cannot confidently select a language from the expected_languages list.

Set language_detection_options.fallback_language to a specific language code (e.g., "en").
fallback_language must be one of the language codes in expected_languages or "auto".
When fallback_language is unspecified, it is set to "auto" by default. This tells our model to choose the fallback language from expected_languages with the highest confidence score.

1 import assemblyai as aai
2 
3 aai.settings.api_key = "<YOUR_API_KEY>"
4 
5 # audio_file = "./local_file.mp3"
6 audio_file = "https://assembly.ai/wildfires.mp3"
7 
8 options = aai.LanguageDetectionOptions(
9     expected_languages=["en", "es", "fr", "de"],
10     fallback_language="auto"
11 )
12 
13 config = aai.TranscriptionConfig(language_detection=True, language_detection_options=options)
14 
15 transcript = aai.Transcriber(config=config).transcribe(audio_file)
16 
17 print(transcript.text)
18 print(transcript.json_response["language_code"])

Confidence score

If language detection is enabled, the API returns a confidence score for the detected language. The score ranges from 0.0 (low confidence) to 1.0 (high confidence).

1 import assemblyai as aai
2 
3 aai.settings.api_key = "<YOUR_API_KEY>"
4 
5 # audio_file = "./local_file.mp3"
6 audio_file = "https://assembly.ai/wildfires.mp3"
7 
8 config = aai.TranscriptionConfig(language_detection=True)
9 
10 transcript = aai.Transcriber(config=config).transcribe(audio_file)
11 
12 print(transcript.text)
13 print(transcript.json_response["language_confidence"])

Set a language confidence threshold

You can set the confidence threshold that must be reached if language detection is enabled. An error will be returned if the language confidence is below this threshold. Valid values are in the range [0,1] inclusive.

1 import assemblyai as aai
2 
3 aai.settings.api_key = "<YOUR_API_KEY>"
4 
5 # audio_file = "./local_file.mp3"
6 audio_file = "https://assembly.ai/wildfires.mp3"
7 
8 config = aai.TranscriptionConfig(language_detection=True, language_confidence_threshold=0.8)
9 
10 transcript = aai.Transcriber(config=config).transcribe(audio_file)
11 
12 if transcript.status == "error":
13   raise RuntimeError(f"Transcription failed: {transcript.error}")
14 else:
15   print(transcript.json_response["language_confidence"])
16   print(transcript.text)

If the language_confidence_threshold you specify is not met you will receive an error message like detected language 'bg', confidence 0.2949, is below the requested confidence threshold value of '0.4'.