In addition to pictures and HD videos, I started this month distributing audio to different agencies. My goal is more to have recordings to support my pictures and videos than rather to increase my microstock earnings. After looking for a suitable recorder, I ordered a Zoom H2 from Amazon. The zoom H2 has a low price tag ($150) and a great sound quality, capable recording at 360-degree and comes with a 1GB SD card and earplugs. If you are looking for a more advanced recorder you can have a look at the Zoom H4n.
Wav files recorded at 44.1 kHz 16 bits are accepted pretty much by all agencies although some are taking 48 kHz 16-bit as well. As the Zoom H2 can record at 96 kHz 24-bit, I use these settings and downsample files before submission.
Like with pictures, agencies are looking for noise-free high quality files and Istockaudio even specify that the signal should be in the final range of -4db to -6db. I use Audacity, a free and open source software, to remove noise if necessary and amplify my audio files.
Like any submission in microstock, quality is preferred over quantity so sounds with a different twist have more chance to be sold. Keywording is quite different than in video and photo and it is advisable to add words to describe the mood of the file in the metadata.
For information, I put in a table below a list of agencies I upload to, along with some, I hope, useful informations. Being an Isyndica user, I take the advantage of their platform to distribute my audio files in few clicks.