| kt | Klystrack Music |
| kt2 | NI Battery 2 Drum Kit |
| kt3 | NI Battery 3 Drum Kit |
| kts | KT-Tech Compressed Audio |
| kxs | Kexis Lossless Compressed Audio |
| la | Lossless Audio Compressed Data |
| laa | LucasArts AdLib Audio |
| latm | AAC Low Overhead Audio Transport Multiplex |
| lb | Low Bitrate Packer Compressed Audio |
| liq | Liquid Tracker Song |
| liw | Cakewalk Music Creator Chord Library |
| lme | LegglessMusicEditor Music Module |
| lmsff | Liquid Audio Player Audio |
| loas | AAC Low Overhead Audio Stream |
| lpc | LPC-10 Encoded Audio |
| lpc10 | LPC-10 Encoded Audio |
| lpcm | Linear Pulse Code Modulated Audio |
| lqt | Liquid Audio Player Data |
| lrc | Lyrics Data |
| lrec | Inter-Tel Web Conferencing Recording |
| lvp | Avaya Voice Player Audio |
| lw | LiteWave Compressed Audio File |
| lwv | Microsoft Agent Linguistically Enhanced Sound File |
| lwv | LiteWave Compressed Audio File |
| m15 | Soundtracker Music |
| m1a | MPEG Audio Layer 1 File |
| m2a | Mpeg-2 Audio |
| m3u | M3U Playlist File |
| m3u8 | M3U Playlist File |
| m4a | Mpeg-4 Audio |
| m4b | Mpeg-4 Audio Book |
| m4e | Yamaha Motif ES Multi Part Editor File |
| m4p | DRM Protected AAC File |
| m4r | iPhone Ringtone |
| m5m | MachFive Audio Data |