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Building a Custom Benchmark for Transcription Tools

9 April 2026 by
Suraj Barman

The Challenge of Transcribing Long-Form Interviews

Transcribing 62 hours of interviews for an archival art project posed a significant challenge, particularly given the unique demands of long-form intellectual conversations. The initial tests with Adobe Premiere revealed an average accuracy rate of 70-80%, which was insufficient for producing a polished, publishable text. This level of accuracy necessitated extensive manual corrections, leading to an inefficient workflow. The need for a more reliable solution prompted an exploration of alternative transcription tools.

Evaluating Transcription Tools Under Real Conditions

Testing multiple tools, including happyscribe, Otter.ai, Sonix, rev, and Whisper, highlighted the challenges of assessing their performance. Short trial clips failed to capture the complexities of domain-specific vocabulary, proper nouns, and the self-correcting conversational style characteristic of the interviews. As a result, it became evident that a more robust evaluation method was necessary to identify the most suitable tool for the project.

Developing a 940-Word Benchmark Test

To address the shortcomings of conventional testing, a custom benchmark text was created. This 940-word document was carefully constructed to include technical film terminology, historical names, and contextually complex language. The goal was to push transcription tools to their limits and identify instances where they might fail to understand or accurately transcribe the content, especially in terms of contextual comprehension and linguistic precision.

Scoring Metrics for Comprehensive Evaluation

The benchmark results were analyzed using the Gemini scoring system, which assessed performance across four critical categories: accuracy, grammar, punctuation, and completeness. The evaluation focused not only on whether words were correctly spelled but also on the tools ability to grasp context and accurately render proper nouns and specialized terminology. This multi-faceted approach ensured a thorough understanding of each tools capabilities and limitations.

Key Insights and Practical Implications

The benchmark provided actionable insights into the performance of various transcription tools under real-world conditions. The results highlighted the importance of domain-specific testing for assessing transcription accuracy, especially when dealing with complex and nuanced content. This approach enabled the identification of tools that could handle the unique demands of the project, reducing the time and effort required for manual corrections and enhancing the overall productivity of the workflow.