How to Test Alphanumeric TTS Accuracy for Voice Apps
Blog post from Deepgram
Alphanumeric text-to-speech errors in tracking numbers, account IDs, verification codes, and product identifiers can lead to customer confusion, call escalations, and substantially higher contact-center costs, yet common TTS evaluations prioritize naturalness over accurate communication of structured data. The text argues that similar-sounding characters, context-dependent numeric readings, inadequate segmentation, and training data focused on natural language make mixed letter-number strings especially difficult for standard systems. It recommends testing realistic domain-specific examples through automated transcription comparison and word error rate, targeting more than 98% accuracy while specifically evaluating confusable characters and long sequences. Suggested improvements include SSML say-as and break tags, pronunciation lexicons, and text-normalization pipelines that classify and segment identifiers before synthesis, while entity-aware TTS tools aim to automate such handling for real-time, high-volume voice applications. Vendor evaluations should confirm relevant SSML support and test mixed codes, tracking numbers, verification codes, and account formats under production-like conditions.
| Trend | Post Mentions | Total Month Mentions | Posts | Companies | MoM |
|---|---|---|---|---|---|
| Voice AI | 2 | 3,022 | 288 | 59 | +34% |
| Deepgram Aura-2 | 1 | 29 | 15 | 3 | -17% |
| Real-time | 1 | 6,860 | 1,508 | 282 | +0% |
| Vector Search | 1 | 2,616 | 517 | 165 | +25% |
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