| nrt | Nokia Phone Ringtone |
| ns2p | Nord Stage 2 Program |
| nsa | Nullsoft Streaming Audio |
| nsf | NES Audio Data |
| nsla | Nero Video Audio Data |
| nsp | KayPentax CSL Audio |
| nst | Noise Tracker Music Module |
| ntn | NOTION Song |
| ntp | NovoTrade Packer Music |
| nus3bank | Super Smash Bros Nus3bank Audio Archive |
| nvf | Creative Labs NOMAD II Audio |
| nwc | NoteWorthy Composer Music |
| nwctxt | NoteWorthy Composer Text |
| nxt | NeXTSTEP Sound File |
| o01 | Typhoon OS Voice Data |
| obw | Superior Drummer Sound File |
| ocdf | OneClickDigital Audio Book |
| odd | Coby Voice Recorder Data |
| ofg | OptimFROG Dualstream Audio |
| ofr | OptimFROG Lossless Audio |
| oga | Ogg Vorbis Compressed Audio |
| ogg | Ogg Vorbis Compressed Audio |
| ogx | Ogg Vorbis Compressed Audio |
| okt | Oktalyzer Music Module |
| olv | OnLive! Traveler Sound |
| oma | Sony ATRAC3 Compressed Audio |
| omg | Sony OpenMG Audio |
| omg | Sony ATRAC3 Compressed Audio |
| oml | OtsAV Media Library |
| omx | OtsAV Media Library Information |
