From the Summer 2021 issue of Living Bird magazine. Subscribe now. Updated January 2023.
It’s an almost universal feeling: the thrill of hearing a mysterious new bird song. And this is usually followed by the question: What is that bird?
Now, the question just got easier: the Cornell Lab’s The Merlin Bird ID app can now recognize bird sounds. At the time of the feature’s launch, Merlin will recognize the sounds of 400+ species from the US and Canada, with that number set to expand rapidly in future updates. (Note: by late 2022, the sound ID feature can identify 870 species in the US, Canada, Western Palearctic (Europe), and the Neotropics. More about sound ID coverage.)
Automatic song ID has been a dream for decades, but sound analysis has always been very difficult. The breakthrough came when researchers, including Merlin lead researcher Grant Van Horn, began treating sounds as images and applying new and powerful image classification algorithms such as those that enable the feature Photo ID of Merlin.
“Every sound recording a user makes will be converted from a waveform to a spectrogram—a way to visualize the amplitude [volume]frequency [pitch], and sound duration,” Van Horn said. “So just as Merlin can identify a picture of a bird, it can now use this picture of the bird’s sound to make an ID,” Van Horn said.
This pioneering sound identification technology has been integrated into the existing Merlin Bird ID app, meaning Merlin now offers four ways to identify a bird: by sound, by a picture, by answering five questions about a bird you’ve seen, or by exploring a list of birds expected where you are.
How to Use Sound ID
Download Merlin. To get the new Sound ID feature, it’s simple download our free Merlin Bird ID app and follow the prompts. If you already have Merlin installed on your phone, tap Get Sound ID.
Look for a Singing Bird (or Birds). If you hear a bird song, just select Sound ID from the main menu and press record. Merlin will immediately start listing the birds it hears. On your phone’s screen you’ll see a list of possible species, complete with a thumbnail photo of the bird and examples of songs and calls for each species.
Adjust Your Setup If Needed. If Merlin is having trouble recognizing your bird, try to approach without disturbing it, and check out these tips to help you cut down on excessive noise.
Take Time to Review. When you’re done recording, you can go back and select a section to see which species are singing which songs. Or tap any of the species in Merlin’s list of possibilities, and you’ll zip back to the point in the recording where that sound occurs. That way you can see and hear what separates it from the other birds you hear, and easily compare each sound to recordings from Merlin’s sound library.
Merlin automatically saves each recording to a folder on your device so you can access it at any time—and those recordings can be deleted or uploaded elsewhere if storage space is an issue. And you can save every bird species Merlin helps you identify in your life list with Merlin’s Save My Bird feature.
If you’re still having trouble installing or using Sound ID, see the Merlin help pages.
Try These Other Fun Ways to Use Sound ID
Try these specific uses of Sound ID, recommended by Merlin project coordinator Drew Weber, to make your birding by ear more enjoyable:
Decode the Dawn Chorus: In spring and early summer, mornings overflow with bird song—sometimes a dozen or more species at once. Merlin can separate these threads and reveal each individual’s identity in the soundscape. And because you can go back and dial in the sound and image of each bird identified, you can listen again and again. Sound ID is a great tool to help you learn bird songs and calls.
Decipher Tricky Chip Notes: As if bird songs weren’t difficult enough, birds often communicate in little more than a few short, non-musical chip notes. Weber says that for many common species, such as Northern Cardinal, White-throated Sparrow, Song Sparrow, and Dark-eyed Junco, Merlin should be able to ID from a clear recording. Give it a try and see how the Merlin fares.
Use Merlin as a Set of “Super Ears”: Some bird songs are easier to hear than others. Birds that sing at a distance—or those with stratospheric songs such as the Blackpoll Warbler, Blackburnian Warbler, and Cedar Waxwing—can be difficult to pick up and harder to ID. You’ll feel like you have a superpower as Merlin detects and displays calls that are hard to identify, and checking what Merlin hears can be a great way to train your own ears.
Does Sound ID Really Work?
To train Merlin to recognize bird sounds, the team gathered around 500 recordings for each species. Working on computers, volunteers cut and classified each recording by hand before feeding it to a machine-learning model that learned each song and its variations. The app also uses eBird observations to determine which birds are most likely to be found at a given place and time.
Even with all of Merlin’s computing power, some species present more of a challenge to ID than others. “A bird like the Willow Flycatcher where all individuals have a similar song across North America, is easier for Merlin to recognize,” said project coordinator Weber. “Compare that to something like a Baltimore Oriole, where each bird has its own twist on the typical song. For a species like this, it can be difficult for Merlin to make the correct ID with very high accuracy. Fortunately, we have thousands of examples of oriole songs and calls available in the Macaulay Library and the model will get better and better over time.
Weber says future updates to Merlin will continue to sharpen its skills. “Users will eventually be able to upload audio directly from Merlin to the Macaulay Library, completing the circle and allowing Merlin recordings to directly train future Merlin machine-learning models .”
Merlin project leader Jessie Barry said Merlin sound ID marks a great advance in people’s ability to connect with and understand the sounds of the natural world around them. Macaulay Library web designer Matt Schloss, who describes himself as an advanced beginner and has beta-tested the app, agrees.
“Merlin helped me find birds that I might not have noticed before. It really makes me feel like I have one super poweror at least improved skills,” Schloss said. “I really think it’s going to change the way people fly.”
Merlin’s new sound identification capability is the product of years of work by the Merlin team, and is made possible by the massive collection of bird observations and sound recordings contributed by the tens of thousands of citizen scientists who use eBird and the Macaulay Library . Thank you
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