Acoustic sensors enable efficient and non-invasive monitoring of a wide range of species, including many that are difficult to monitor in other ways. Although they were initially limited in application scope largely due to cost and hardware constraints, the development of low-cost, open-source models like the Audiomoth in recent years has increased access immensely and opened up new avenues of research. For example, some teams are using them to identify illicit human activities through the detection of associated sounds, like gunshots, vehicles, or chainsaws (e.g. OpenEars).
With this relatively novel dimension of wildlife monitoring rapidly advancing in both marine and terrestrial systems, it is crucial that we identify and share information about the utility and constraints of these sensors to inform efforts. A recent study identified advancements in hardware and machine learning applications, as well as early development of acoustic biodiversity indicators, as factors facilitating progress in the field. In terms of limitations, the authors highlight insufficient reference sound libraries, a lack of open-source audio processing tools, and a need for standardization of survey and analysis protocols. They also stress the importance of collaboration in moving forward, which is precisely what this group will aim to facilitate.
If you're new to acoustic monitoring and want to get up to speed on the basics, check out these beginner's resources and conversations from across the WILDLABS platform:
Three Resources for Beginners:
- Listening to Nature: The Emerging Field of Bioacoustics, Adam Welz
- Ecoacoustics and Biodiversity Monitoring, RSEC Journal
- Monitoring Ecosystems through Sound: The Present and Future of Passive Acoustics, Ella Browning and Rory Gibb
Three Forum Threads for Beginners:
- AudioMoth user guide | Tessa Rhinehart
- Audiomoth and Natterjack Monitoring (UK) | Stuart Newson
- Help with analysing bat recordings from Audiomoth | Carlos Abrahams
Three Tutorials for Beginners:
- "How do I perform automated recordings of bird assemblages?" | Carlos Abrahams, Tech Tutors
- "How do I scale up acoustic surveys with Audiomoths and automated processing?" | Tessa Rhinehart, Tech Tutors
- Acoustic Monitoring | David Watson, Ruby Lee, Andy Hill, and Dimitri Ponirakis, Virtual Meetups
Want to know more about acoustic monitoring and learn from experts in the WILDLABS community? Jump into the discussion in our Acoustic Monitoring group!
Header image: Carly Batist
Put your acoustic monitoring skills to the test in The Cornell Lab of Ornithology's Birdsong Identification Kaggle Competition. Participants will compete to identify as many bird vocalizations as possible in in...
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24 February 2020
Ol Pejeta Conservancy partners with conservation and technology organisations to kick-start a research and innovation centre for wildlife conservation
31 May 2019
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13 May 2019
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3 March 2019
In this case study, Science Reporter Jamie Morton tells the story of how Kiwi scientists are teaming up with a local underwater robotics company to gain world-first insights into the lives of whales in Antarctica.
4 February 2019
As human impacts on the world accelerate, so does the need for tools to monitor the effects we have on species and ecosystems. In this article, Ella Browning and Rory Gibb share insights from their recent review paper...
4 December 2018
Article
In this case study, conservation ecologist Ayesha Tulloch takes us behind the scenes of her recent paper, which came out in Nature Ecology & Evolution earlier this month. In this paper, Ayesha and her team present a...
20 August 2018
Last month, the 2018 Ecoacoustics Congress was held in Brisbane. Bringing together scientists, natural resource managers, industry and artists, participants explored the ways that sound can deepen our understanding of...
25 July 2018
June 2024
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April 2024
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The Inventory User Guide
1 May 2024 12:46pm
Introducing The Inventory!
1 May 2024 12:46pm
Hiring Chief Engineer at Conservation X Labs
1 May 2024 12:19pm
Affordable acoustic monitors for "whispering" bats?
30 April 2024 8:31pm
30 April 2024 11:19pm
I don't know specifically, but you could reach out to Wildlife Acoustics support or Phil (respectively) and I'm sure they would have details for you! The Echometers have the specs (mic sensitivity, etc.) published on the website as well if you want to check those first.
30 April 2024 11:28pm
Also some other bat experts I'd recommend reaching out to, if you haven't already (for this and any bat acoustic questions) - Adrià López-Baucells, Nils Bouillard, Kate Jones, Stuart Newson, plus obviously anyone at the big orgs like Bat Conservation Int'l, etc.
Attaching a directional microphone to a Wildlife Acoustics ultrasonic recorder?
29 April 2024 4:47pm
30 April 2024 4:28pm
Hi Luke, sounds like an interesting project! One thing to note is the ultrasonic Wildlife Acoustics unit you're looking at is already fairly directional. Take a look at the horizontal directionality plot towards the bottom:
You can see that for the relevant frequencies for slow lorises ultrasonic calls (40-60 kHz), there is 25-30 dB difference between 0 and 180 horizontal degrees. It's not perfect, but is close to some directional mics, and if it works well enough for your project it would save a lot of time and testing!
If you do choose to integrate an external directional microphone, be careful with microphone placement to avoid potential ultrasonic reflections from any hard flat surface like a tree trunk, water surface, or the instrument housing itself. Here's an example of some echo calls from reflective surfaces from bat vocalizations:
It would be helpful to hear how you plan on obtaining behavioral information (and what kind) to correlate with vocalizations? Observations, cameras, biologgers, etc.? This could inform responses a bit more.
30 April 2024 6:19pm
Hi Jesse,
Thank you so much for your reply and for the fantastic knowledge and resources! I was unfamiliar with the plots, so thank you for providing some interpretation- I will have to work to better understanding them. This may change things (I was going off of experience from field work with the last iteration of this WA recorder which had omnidirectional recording) and I may choose to pilot the recorder without an external microphone this summer.
Regarding my plan for collecting behavioral data, I plan to follow 15 wild individuals in a reserve in Thailand (mostly dry evergreen and dry dipterocarp forest with some human modified areas). I intend to use instantaneous focal sampling to observe lorises in two shifts between 18:00-06:00h. During these focal follows I will record all behaviors at 5-min intervals and use all-occurrences sampling for social and feeding behaviors, using an established slow loris ethogram. Simultaneously, I plan to record vocalizations, with the help of a research assistant and field guide. So we will be carrying the recorder with us during behavioral data collection. I intend to match up the timestamped loris vocalizations with the behavioral data to understand the call's function.
30 April 2024 7:00pm
If you have the resources, I would suggest testing the sensitivity and directionality of the system at relevant frequencies both with and without an external mic, and let the results dictate which will be best for your case study.
Another thing to think about since you are manually taking the recordings is if a WA unit is really necessary. You're paying for the technology of a remote system without needing it. Other cheaper handheld recorders (such as Zoom recorders) could free up $$ for a higher quality directional microphone. Although of note is that common Zoom recorders like the H4n only sample up to 96kHz for which the upper frequency limit (48kHz) is getting very close to the frequencies you're likely wanting to measure.
Acoustically Transparent Epoxy
26 April 2024 3:26pm
26 April 2024 4:27pm
Sounds tricky, Aerogel? haha.
Could maybe get away with using conformal coating and an acoustic membrane similar to what a cellphone mic uses.
Or locate the mems mic near the edge of the pcb and mask off that area when potting.
29 April 2024 9:19am
Sounds interesting.
We all used acoustic membranes.
Just like @BrettMargoSupplies suggested.
A friend of mine had really bad results with animal borne
mics where the pcb was potted and the mic was just covered by a thin layer of epoxy where it hit the surface.
That was not working good!
Greetings from thhe woods,
Robin
29 April 2024 5:37pm
Thanks for the reply. I'm curious to hear more about your friend's issues with this set up!
The Bat Conservation Trust - Research Scientist (Quantitative ecology)
24 April 2024 7:29pm
WILDLABS AWARDS 2024 - Fostering bat conservation and citizen science in Zimbabwe: Establishing bat groups and training individuals to use bat detectors
4 April 2024 12:12pm
8 April 2024 9:29am
Thank you Carly!
We have over 60 bats recorded in Zimbabwe
19 April 2024 2:16pm
Abigail. I would love to know more and potentially support the initiative. Please send me more info on [email protected]
24 April 2024 2:27pm
Thank you Robyn. Sure I will send more information to your email
Drop-deployed HydroMoth
2 April 2024 10:20am
5 April 2024 2:04pm
Hi Sol! This seems like an awesome project! I have a few questions in response: Where were you thinking of deploying this payload and for how long?
Regarding hydromoth recorders, there have been several concerns that have popped up in my work with deploying the them at this depth because it's a contact type hydrophone which means it utilizes the case to transmit the sound vibrations of the marine soundscape to the microphone unlike the piezo element based hydrophones.
- At 30-60m you will likely have the case leak after an extended period of time if not immediately. The O-ring will deform at this depth, especially around the hinge of the housing. The square prism shape is not ideal for deep deployments you describe.
- After that depth and really starting at about 50m, a major concern is synthetic implosion from the small air pocket of the hydromoth not having a pressure release valve and lithium ion batteries getting exposed to salt water. This type of reaction would cause your other instruments to probably break or fail as well.
- You are unlikely to get a signal with a reinforced enclosure. The signal is generated via the material and geometry of the housing. The plastic will probably deform and mess with your frequency response and sound to noise ratio. If you place it against metal, it will dampen the sound quite a lot. We tried to do this, but the sensitivity is quite low with a large amount of self noise.
A side note: for biodiversity assessments, the hydromoth is not characterized and is highly directional, so you wouldn't be able to compare sites through your standard aocustic indices like ACI and SPL.
That said if you are deploying for a short time, a hydrophone like an Aquarian H1a attached through a penetrator of a blue robotics housing that contains a field recorder like a zoom recorder may be optimal for half a day and be relatively cheaper than some of the other options. You could also add another battery pack in parrallel for a longer duration.
15 April 2024 6:53am
Hi Matthew,
Thanks for your advice, this is really helpful!
I'm planning to use it in a seagrass meadow survey for a series of ~20 drops/sites to around 30 m, recording for around 10 minutes each time, in Cornwall, UK.
At this stage I reckon we won't exceed 30 m, but based on your advice, I think this sounds like not the best setup for the surveys we want to try.
We will try the Aquarian H1a, attached to the Zoom H1e unit, through a PVC case. This is what Aquarian recommended to me when I contacted them too.
Thanks for the advice, to be honest the software component is what I was most interested in when it came to the AudioMoth- is there any other open source software you would recommend for this?
Best wishes,
Sol
21 April 2024 7:10pm
Hey Sol,
No problem at all. Depending on your configuration, the Audiomoth software would have to work on a PCB with an ESP32 chip which is the unit on the audiomoth/hydromoth, so you would have to make a PCB centered around this chip. You could mimic the functionality of the audiomoth software on another chip, like on a raspberry pi with python's pyaudio library for example. The problem you would have is that the H1A requires phantom power, so it's not plug and play. I'm not too aware with the H1e, but maybe you can control the microphone through the recorder that is programmable through activations by the RPi (not that this is the most efficient MCU for this application, but it is user friendly). A simpler solution might be to just record continuously and play a sound or take notes of when your 10 min deployment starts. I think it should last you >6 hours with a set of lithium energizer batteries. You may want to think about putting a penetrator on the PVC housing for a push button or switch to start when you deploy. They make a few waterproof options.
Just somethign else that occured to me, but if you're dropping these systems, you'll want to ensure that the system isn't wobbling in the seagrass as that will probably be all you will hear on the recordings, especially if you plan to deploy shallower. For my studies in Curacao, we aim to be 5lbs negative, but this all depends on your current and surface action. You might also want to think about the time of day you're recording biodiversity in general. I may suggest recording the site for a bit (a couple days or a week) prior to your study to see what you should account for (e.g. tide flow/current/anthropogenic disturbance) and determine diel patterning of vocalizations you are aiming to collect if subsampling at 10 minutes.
Cheers,
Matt
Thoughts on RooBadge?
2 April 2024 2:55pm
5 April 2024 12:31pm
Sound deterrents to prevent collisions with Kangaroos in Australia have been sold for many years. None have been shown to work. Whether the Volkswagen device will be any better waits to be seen. Collision data will have to be collected for a while to see if the VW device has any effect on collision rate.
8 April 2024 12:49am
That is an interesting concept, and it would be great if something out there worked. In the meantime, I will try not to drive at dusk 🦘
At one point, I knew the "sonic" animal guards were the most stolen components of cars. You head in, get groceries, and come out, and they are gone. They weren't on the car long enough for me to confirm that would work
20 April 2024 2:40am
Totally agree.
Inititally sceptical until I saw Helena and Graeme were involved.
MJ
4th International workshop on vocal interactivity in-and-between humans, animals, and robots
19 April 2024 3:03pm
Webinar: Bats and Wind Energy
18 April 2024 6:11pm
WILDLABS AWARDS 2024 - BumbleBuzz: automatic recognition of bumblebee species and behaviour from their buzzing sounds
12 April 2024 8:37am
12 April 2024 8:41pm
Super great to see that there will be more work on insect ecoacoustics! So prevalent in practically every soundscape, but so often over-looked. Can't wait to follow this project as it develops!
17 April 2024 10:23am
Thanks Carly! I will keep anyone interested in this project posted on this platform. Cheers
WILDLABS AWARDS 2024 - TimeLord: A low-cost, low-power and low-difficulty timer board to control battery-powered devices
5 April 2024 3:29pm
16 April 2024 9:34am
Thanks @Freaklabs, I think you'll really enjoy getting involved with this too as we're looking for input from makers in the community to get the most from the approach and to capture features and usability ideas from a large number of people.
I've a new modular drop-off tag build using @Rob_Appleby's original SensorDrop board that I think would be great for this project too to see if we can drop different compartments, or do various different timed events with the one TimeLord board.
Most importantly, we have to make it play a MIDI version of the DoctorWho theme song when you arm the device. That has to be the #1 feature if you ask me!
16 April 2024 9:35am
Reminds me that we should look at both terrestrial and marine applications when we get stuck in to the demo builds to make sure we cover use cases
16 April 2024 10:22am
'Most importantly, we have to make it play a MIDI version of the DoctorWho theme song when you arm the device. That has to be the #1 feature if you ask me!'
Seconded!
WILDLABS AWARDS 2024 - Developing AudioMoth for the detection of infrasonic elephant rumbles
11 April 2024 7:35am
11 April 2024 4:05pm
Awesome project!!
Wildlife Drones will be at the 21st Australasian Bat Society Conference
9 April 2024 6:03am
WILDLABS AWARDS 2024 - Underwater Passive Acoustic Monitoring (UPAM) for threatened Andean water frogs
30 March 2024 3:54pm
2 April 2024 2:35pm
Thanks @carlybatist for your suggestions! In deed we are looking for open code/free access alternatives for automated species recognition
5 April 2024 12:13pm
Congratulations, very exciting! Keep us updated!
7 April 2024 6:09pm
This is so cool @Mauricio_Akmentins - congrats and look forward to seeing your project evolve!
WILDLABS AWARDS 2024 - FinDrop: Accessible Acoustic Monitoring for Mesophotic Marine Environments
5 April 2024 10:22pm
7 April 2024 6:07pm
Congrats @MattyD797 and team!!! We do a lot of work in the underwater bioacoustic realm and your tool certainly seems like it would be a great instrumental addition to the community. Look forward to learning more about your project!
Liz
Underwater advertisement call of the threatened Telmatobius rubigo (Anura: Telmatobiidae
6 April 2024 9:56pm
Bioacoustic device security in urban parks
8 March 2024 2:49pm
24 March 2024 4:53am
Yes, I agree with Panji......make sure you have notes of where you put them and remember that photos of trees without leaves look completely different 6 months later......not that I would ever make that mistake.........well not again......especially after spending 2 days trying to find 3 ARU's.
24 March 2024 9:38pm
We suggest and use Python Locks for urban areas here in Australia. Can also screw the Mini 2 to a tree or phone post with the python lock.
5 April 2024 12:55pm
We've deployed passive acoustic monitors in various urban environments without any issues of theft, even in locations where camera traps and other technology has been historically taken or vandalised. I think acoustic sensors generally look less valuable than other technology, and I would recommend removing or covering any stickers or labels on devices that would otherwise make them more appealing! Placing them in hedgerows or on trees with some (but not too much!) foliage will help keep them well hidden too.
Not so silent spectators: How spectator vessels at international sailing regattas alter marine soundscapes
3 April 2024 4:50pm
Check out how water-based sporting events are impacting underwater noise pollution for marine life.
Seventh International Conference on the Effects of Noise on Aquatic Life
3 April 2024 4:34pm
Postdoctoral Research Associate in Ecoacoustics
2 April 2024 2:49pm
Think Wildlife Podcast | The Role of Bioacoustics in Conservation with Bourhan Yassin, Founder of Rainforest Connection
28 March 2024 11:27pm
Hi,
I am Anish and I'm new to this platform! I host the Think Wildlife Podcast and wanted to share a recent episode with Bourhan Yassini. We talk in-depth about the role of AI and bioacoustics in conservation. Tune in to listen more!
AI for Conservation!
4 March 2024 8:51pm
22 March 2024 12:29pm
Welcome, Have you considered participating in any of the AI for Good challenges. I find it is good way to build a nice portfolio of work. Also contributing to existing open source ML projects such as megadetector or to upstream libraries such as PyTorch is good way to getting hired.
22 March 2024 5:57pm
Thank you for the tip! I'll definitely consider contributing to open source projects and taking part in challenges :)
25 March 2024 5:22am
We could always use more contributors in open source projects. In most open source companies Red Hat, Anaconda, Red Hat and Mozilla, people often ended up getting hired largely due to their contributions on open source projects. These contributions were both technical such as writing computer code and non-technical such as writing documentation and translating tools in their local language.
Recording Orthoptera Sounds: International Workshop (Italy)
22 March 2024 9:25pm
30 April 2024 9:25pm
Thank you, Carly!
Do you know if these are sensitive enough to detect the quieter bat species?