The Olympus 4GB DM-901 Digital Voice Recorder has 4GB of internal memory and an SD/SDHC/SDXC memory card slot that allows you to expand the recorder's storage capacity by up to 64GB. It features built-in Wi-Fi as well, which works with the Olympus Audio Controller app for iOS or Android mobile devices. Together, you can use your smartphone to remotely control the recorder's main features. This means you can place the recorder right next to the speaker and control it from the back of the room using your smartphone and the app. You can even start and stop recordings remotely so you only record what you need. Plus, you can use pictures captured from your smartphone as visual index markers.
The DM-901 can record and playback audio files using the WMA, MP3 and PCM (WAV) formats. It uses a zoom microphone for recording, but there's also a mic input for connecting an external microphone. There's a headphone jack and a built-in speaker for listening back to recordings as well. The recorder features sensitivity controls for the built-in zoom mic, which allow you to focus the microphone directly on the audio source - even from a distance - by increasing the sensitivity when the subject is further away. Other features include Voice Guidance and Voice Balancer technology, a 2" full color LCD screen, an intuitive user interface, and noise cancellation technology.