CLT Blog’s Justin Ruckman decoded SEC filings to turn up an intriguing recent Amazon acquisition: Yap, a Charlotte-based speech-recognition startup best known for its recently shuttered voicemail transcription app and backend services for some of Microsoft’s voice-to-text application.

So far, Amazon hasn’t publicly commented on or even confirmed Yap’s acquisition, and didn’t immediately respond to our attempts to find out what it plans to do with the company. It’s an uncharacteristic buy for them, since the company traditionally hasn’t bothered much with voice technology. Amazon’s Kindle Fire t...