AssemblyAI: Top Speaker Diarization Libraries and APIs to Watch in 2022

Speaker diarization technology has become increasingly vital for various applications, from automatic speech recognition (ASR) to meeting transcription and call center analytics. According to AssemblyAI, an industry leader in speech recognition, speaker diarization involves segmenting and labeling an audio stream by speaker, enabling a clearer understanding of who is speaking at any given time.

What is Speaker Diarization?

Speaker diarization aims to answer the question: "Who spoke when?" It involves two main tasks:

1. Speaker Detection: Identifying the number of distinct speakers in an audio file.
2. Speaker Attribution: Assigning segments of speech to the correct speaker.

This process results in a transcript where each segment of speech is tagged with a speaker label, making it easier to distinguish between different voices. This improves the readability of transcripts and enhances the accuracy of analyses that depend on understanding who said what.

How Does Speaker Diarization Work?

Speaker diarization involves segmenting an audio file into utterances, which are then processed by deep learning models to produce embeddings that represent the unique vocal characteristics of each speaker. The embeddings are clustered to determine the number of speakers and to assign speaker labels to each utterance. This process can handle up to 26 speakers in a single audio file with high accuracy.

Why is Speaker Diarization Useful?

Speaker diarization significantly enhances the readability of transcripts by clearly identifying speakers, saving time and mental energy. It also serves as a powerful analytic tool for identifying patterns and trends in speech, making predictions, and improving communication in various settings such as call centers, podcasts, and telemedicine platforms.

Top 3 Speaker Diarization Libraries and APIs

Several libraries and APIs can help developers implement speaker diarization in their projects. Here are the top three:

AssemblyAI

AssemblyAI offers a highly accurate Speech-to-Text API that includes speaker diarization. Developers can easily enable this feature when processing audio or video files through the API, resulting in transcripts with accurate speaker labels.

PyAnnote

PyAnnote is an open-source speaker diarization toolkit based on the PyTorch machine learning framework. While it offers some pretrained models, developers may need to train its neural building blocks to customize their own speaker diarization models.

Kaldi

Kaldi is another open-source option for speaker diarization. Developers can either train the models from scratch or use pre-trained models available on the Kaldi website. Kaldi requires some initial setup but offers robust capabilities for speaker diarization.

Limitations of Speaker Diarization

Despite its many advantages, speaker diarization has some limitations. It currently works only for asynchronous transcription and struggles with real-time transcription. Factors such as speaker talk time and conversational pace also impact its accuracy. For instance, speakers who talk for less than 15 seconds may not be accurately identified, and conversations with significant background noise or over-talking can reduce model accuracy.

Conclusion

Speaker diarization technology is continuously evolving, driven by advances in deep learning research. As models improve, the accuracy and utility of speaker diarization will continue to grow, offering valuable insights and efficiencies across various applications. Developers and product teams can leverage top libraries and APIs like AssemblyAI, PyAnnote, and Kaldi to integrate this powerful technology into their projects.