ตัวแปลงไฟล์ออนไลน์ฟรี HTK เป็น OGG

Single channel 16-bit PCM format used by HTK, a toolkit for building Hidden Markov Model speech processing tools

This format is free, which apparently is one of the reasons for its popularity. The used codecs supports variable bit rates (as a default), and .ogg files usually play back easily on all platforms. All things being equal, the sound quality exceeds that of mp3 somewhat.