Open Mic: a better and simpler way to record bird sounds with smartphones
Ted Floyd, in his recent article in the Birder’s Guide to Gear, said it best—recording birds with your smartphone is awesome! The ability to record bird sounds with your smartphone opens doors that were at one time only dared by skilled recordists. And not only that, as Ted points out, it’s pretty easy to do.
Although your smartphone is equipped with a video camera that can record sound, using the video camera is a cumbersome way to record bird sounds. A much simpler way to record bird sounds is to download a free recording app. These free apps are easy to use and require little time investment. All you need to do is configure your settings once and you’re all set. The Macaulay Library at the Cornell Lab of Ornithology has information on how to configure several recording apps for Android and iOS phones. Many of these apps even have seamless sharing to transfer recordings to your computer.
The Macaulay Library recommends choosing an app that lets you record uncompressed .wav files (see our review of apps). That’s technical speak for an audio format that provides the highest quality and most accurate copy of wildlife sounds. It’s also the format used by sound archives dedicated to long-term preservation of audio.
Built-in smartphone apps such as voice memos and your video camera record audio in .mp3 or .m4a formats, which causes loss of acoustic data to make the files smaller in size. These compressed file formats are designed primarily for music, where audio important to human hearing is kept while sacrificing frequencies considered less valuable. When it comes to bird songs, however, the audio deletion can be misleading because birds hear sounds differently than we do. This means that audio that might be unimportant for humans could be important for birds. Compression is even visible in spectrograms—the visual representations of songs; note the white spots in the spectrogram below where data has been lost.
The white gaps in the middle of each note are the result of compression where valuable data has been lost.
Also consider that in the age where smartphones can store 64 gigabytes or more of data and 1 terabyte hard drives cost less than $100, file size isn’t an issue anymore.
When you are ready to archive your media in the Macaulay Library with your eBird checklist, we recommend taking a few extra moments to make your recording even more valuable. Just as you might edit your photos, you’ll want to do the audio version of light photo editing. We recommend using a free sound editing software such as Audacity or Ocenaudio to prepare your recordings prior to upload. The first step is to save a copy of your original .wav recording. Second, trim the ends of your recording to get rid of any extraneous handling noise, much like cropping your photos. Third, give your recording a volume boost, by normalizing the recording to -3dB. And finally, avoid filters that remove background noise or other cosmetic editing. Not only is this type of filtering unnecessary, you are removing valuable information from your recording. See Macaulay Library’s how-to guide for additional information on preparing your sound files.
If you have recordings made with your smartphone video camera or other camera setup, do not simply change the file extension to .wav. Changing the file extension does not convert the file to a different format and makes the file misleading to anyone trying to use it. To convert a video file, you need to use an audio editing program such as Audacity or Ocenaudio that can strip the audio channels out of the video and convert them into .wav format.
A dedicated smartphone app is the way to go. Not only do you avoid the extra steps of stripping out the audio from a video, the reduced file size of an audio file allows you to make longer recordings, which are much more valuable for science. The .wav files you record and contribute to the Macaulay Library will be more valuable to researchers and others for years to come. When Arthur Allen, Paul Schwartz, L. Irby Davis and other pioneers in the field were recording in mid-1900’s they could never have dreamed of how their recordings would be used today.
Researchers use sound recordings for a myriad of topics, from helping understand species definitions, to investigating the evolution of sound learning in birds, to understanding why some female birds sing, and more. And YOU can use them too! Nothing brings back memories of your birding adventures as well as listening to something you recorded. Join the community of more than 8,500 recordists who are helping create audio snapshots of birds in today’s landscape. Visit our how-to guide for tutorials, gear guides, and more.
[This article was first published on December 11, 2018 on the ABA blog, and is reprinted here with permission.]