Review: The AudioMoth USB Microphone from Open Acoustic Devices

This is a review of the new (yet-to-be available) AudioMoth USB Microphone designed by Open Acoustic Devices.

It is not currently available to the public (at the time of this writing). I must say that I feel privileged and honoured to be the first to get one. I’ve been fortunate to be able to test, review, and publish my thoughts on this brand-new USB Mic.

This very small unit arrives in an appropriately sized box.

(AA-sized battery for scale)

The size, is very small - Specifically: 35mm x 40mm. The weight, is very light!

Unboxing / AA size battery shown for scale 

The price of this unit, has not been officially announced. However, I’m told it will be under $100 US. Based solely on the fact that this small, versatile unit works very well across multiple software applications, I have a feeling it will be quite popular.

Clever business card!

As seen in photos, this unique unit has a green hard plastic outer casing. If you are familiar with some of the documentation provided by Open Acoustic Resources, you will have seen a photo of the Mic in both green and dark blue plastic cases. 

 Page 4 of 4, of the documentation mentioned above.

At this point I cannot confirm whether or not the unit will be available in dark blue, when it is released/available for public purchase.

Back view of AudioMoth USB Mic

From the outside/back view — you can see the area for the Micro USB connector, and a female 3.5 mm jack for plugging in an additional microphone. Or, as mentioned in their documentation "...a hydrophone" 

Thanks! That's all it took to get me thinking about my (unbuilt) DIY hydrophones... 

Having this additional 3.5 mm jack provides a great resource/platform for experimenting with additional microphones - Such as others you have on hand; mini-shotgun microphones, shotgun microphones, and DIY microphone projects.

When a microphone is plugged into the 3.5mm jack, the AudioMoth USB microphone is (temporarily) disabled. 

Inside is a perfectly (snugly) fitted, small circuit board.

Where the magic happens.

 

It's worth mentioning, that this AudioMoth USB Mic is a modified version of the original AudioMoth - With: the battery holder, 256KB SRAM, SD card holder, and real-time clock crystal removed.

I found both the external and internal design to be very well done - it also didn't take long at all before I became very pleased with it's ease of use, and it's general performance.

For a very quick start:

• Download the free AudioMoth Live App - from the Open Acoustic Devices Website.
• Out of the box - simply plug in a mini USB cable to the Mic itself, with the other end plugged into a laptop.
• Launch software - Click the green play button - this begins the spectrum display scrolling from right to left.

I would strongly recommend printing out the documents which you find of most interest, to have to hand for quick-reference. However, for the sake of being thorough - here are the functions behind the switch settings of The AudioMoth USB Mic:

USB/OFF: When the switch is set to USB/OFF the sample rates, gain and filter options can be set through the AudioMoth USB Microphone App above. The green LED will light when USB is connected.

​

DEFAULT: When the switch is set to DEFAULT the device will enumerate as a USB microphone implementing the set sample rate and gain. The green LED will flash at a rate determined by the sample rate (identical to that of the standard AudioMoth firmware).

​

CUSTOM: When the switch is set to CUSTOM the device will again enumerate as a USB microphone implementing the sample rate and gain settings as above, and also the requested filter and advanced settings. The red LED will flash at a rate determined by the sample rate (identical to that of the standard AudioMoth firmware). You can switch between DEFAULT and CUSTOM whilst recording to see the effect of these settings.

I generally keep mine in 'Default' mode, for the majority of my recording.

The (proposed) relatively low cost of this USB Microphone will make it an attractive bit of kit for many people. Not just those involved in ultrasound recording (bats!), but those involved in wildlife sound recording in general.

Since it not only excels at recording ultrasonic sounds—it also does a good job of recording audible sounds as well.

Here is just one of many examples of recordings I made: Two Baby Barred Owls vocalizing at night.

Recorded with the brand-new AudioMoth USB Mic from Open Acoustic Devices, at an approximate distance of 15 meters.

This makes The USB Mic a good choice for those who intend on recording both ultrasonic and audible sounds.

This new microphone would also be very good for bat detecting enthusiasts/obviously, as well as those interested in recording other wildlife sounds. 

From my extensive testing, I’ve also concluded that Professionals will find it very useful as well... I find it to be robust, and pleasantly sensitive using it's default settings. You plug it into your laptop, launch the AudioMoth Live App - And it just works! Audio is coming over your laptop's speakers, loud and clear.

I believe it would be perfect for having a listen around an area, and/or before deploying the main/overnight recorders. It would be perfect for confirming the presence of animal vocalizations before deploying other overnight equipment... 

This relatively inexpensive unit, would make an excellent addition to the recording equipment of the typical recording enthusiast. With the combination of being affordable, and providing very good performance. I found the recordings to be on par with several of the detectors available today. 

I've used The AudioMoth USB Mic on: An old Samsung smartphone, running the Bat Recorder App; as well as on an iPhone running Ultrasonic Analyzer. No issues were encountered. 

I've made countless recordings of my local bats, and they were all excellent! During recording, and later on when playing back and analysing. 

These recordings will be shown/played/discussed in an upcoming presentation on The BatAbility Club (on 7/24/2023).

I hope to add some spectrograms to this review in the near future also... For now, here's a recent screenshot:

This is most likely one of my local Big Brown Bats (Eptesicus fuscus)

I'm also planning to add some related material to my YouTube channel, and SoundCloud for convenience. 

To go over the steps/to reiterate:

1. Install the AudioMoth Live App downloaded from here.
2. Plug in The USB Mic using the length of USB cable appropriate for your needs.
3. Wait for your laptop's operating system to detect and recognize The USB Microphone.
4. Launch the AudioMoth USB Live App Audio.
5. You want to choose 'File' > 'Enable high sample rate' (typically).
6. Press the green Play button (starts spectrogram scrolling).
7. Select 'Auto save file duration' (or capture wav files yourself manually).

When you first plug-in and use this AudioMoth: You will immediately recognize how accurate the microphone is at detecting and reproducing sound. There is also an option to select 'Off' which stops the spectrogram scrolling/screen.

The 'Monitor' setting, gives you the option of monitoring large swaths of incoming sound. You may also select 'Heterodyne' to provide the advantage of a heterodyne bat detector to the incoming sound. 

Pros:

• Very user-friendly, not much effort required to begin recording.
• May be used to record ultrasonic and audible sounds.
• Extremely small and lightweight.
• Described as splash proof, which means it won't deteriorate from some (accidental) light rain.
• The AudioMoth Live App works well with The Dodotronic Ultramic Evo384K Mic - It may work with the USB Mic you currently have to hand...

Cons:

• Omnidirectional only.
• Not available for purchase yet.

Getting your hands on one of these USB Mics (when they become available to the public) may be different than what you're used to. It depends...

As for where and when to order: I can't say at this time. Stay tuned! And keep checking the Open Acoustics Devices Site, as well as GroupGets and LabMaker (Earth and Ecology page).

Mid-August Update: I'm working on adding just a bit more to this review. Mostly, screen captures and an additional summary.

For now, I cannot emphasize the following statement enough:

The AudioMoth USB Microphone is a simple and robust device, which allows you to begin recording bats quickly, easily, and accurately. Especially when using the AudioMoth Live App on a laptop!

I want to be clear: This new AudioMoth USB Mic is a pleasure to use. The AudioMoth Live App designed for use with it (works with other USB Mics too) is refreshingly simple. I'm very happy with the way it represents what the Mic is hearing, as well as how easily it allows me to save the recordings.

Until next time,

Happy bat detecting!

The USB Microphone By Open Acoustic Devices Has Arrived!

Just a brief post, for now: The USB Mic, which has just been developed by Open Acoustic Devices arrived the other day (here in upstate NY - From England).

There will be a full review here on the blog in the future. However, the first debut and discussion of it, will be on July 24th, via The BatAbility Club. You may follow this link: The BatAbility Club to find out more about them.

As mentioned in the preceding post, the software covered, will mainly be:

• Bat Recorder - An Android phone App from Google Play Store.
• Audiomoth Live App - by Open Acoustic Devices.
• With a brief look at Ultrasonic Analyzer (iPhone App).

Unboxing 

I'm very excited to share my first impressions of this brand-new USB Microphone here; after having Tweeted about it, etc.

This is the back of the microphone

Back view of the microphone plugged into laptop 

• It's small and light - All that's needed is a USB to Micro USB cable.
• Using it (with The AudioMoth Live App) is super simple.
• It has a built-in 3.5mm jack - for plugging-in an additional microphone. This is an outstanding feature for experimenters!
• It works flawlessly on laptops.
• I've used it without incident on Android smart phones (with Bat Recorder).
• I've also used it on my iPhone (w/ adapter) and Ultrasonic Analyzer (iPhone App).

I mention this last point, because it demonstrates how versatile this Mic is - It works well on an App which was developed before the Mic existed. The iPhone App even displays the name of the Mic. The reason why isn't earth-shattering; but it's still neat!

It is also a great indicator of the smooth operation that one can expect, from this little piece of hardware. I also like the idea of the documentation stating its splash proof; thanks to the use of a Gore® protective vent over the Mic element. Not that I would ever "test" its ability to repel water (and neither should you) it's just nice to know it's there.

It may begin to drizzle one night, when you least expect it...

Obviously, I'm just sharing very basic bullet points - These points (and others) will be greatly expanded upon going forward, and in future blog posts.

It is a pleasure to use, provides sensitivity similar to a (low-cost) shotgun microphone - the compact types made for DSLRs - with the advantage of ultrasound, of course. The intuitive AudioMoth Live App allows one to tune (the Mic) all the way down to 12kHz. 

Until next time,

Happy bat detecting!

Some Random Thoughts, Progress Updates and Other Marginalia

Just some random thoughts, progress updates and other marginalia.

Happy New Year! 

Update Post - Late-December/Early January Activities - I apologize for not posting more frequently, I originally intended to - but frankly, my chronic pain has been getting the better of me lately.

I'm happy to report that coyotes, barred owls, great horned owls, and others have been heard vocalising in my area. My attempts at recording with just a Zoom H1n portable recorder, produced less-than-stellar results (pretty dismal in most cases). Being limited to using only the built-in Mics; this was to be expected.

I was working on raising funds for a decent shotgun microphone. I've always wanted to get a Rode NTG-2. Ever since I reached out to the author of this book:

 

I wanted to find out exactly which equipment he used, to produce the excellent recordings of singing insects on the included CD. The microphone used, was the Rode NTG-2; along with a Marantz digital field recorder (one of the no longer produced PMD-661's).

Note: If you try to track down the Marantz PMD-661 (as I have) you'll only occasionally see one pop up on eBay. And unfortunately, it's not common to find one in excellent -to- very good condition.

As for currently available handheld digital recorders, the Zoom H5 seems like just the ticket, to pair with just about any microphone. 

I've been researching, as well as building:

• Several DIY ultrasonic microphones (nothing fancy or too noteworthy yet).
• A couple of audible-range microphones (again, nothing special/noteworthy).
• Simple amplifiers for the above Mics.
• DIY Amplifiers specifically for hydrophones.

I'd done a bit of "research" on DIY hydrophones as well; and the Zoom H5 is mentioned favourably whenever the subject of hobbyist-level hydrophones is discussed. In some cases, even when the discussion involves Pro-level hydrophones.

Also, I've been keeping busy trying to build a (working!) DIY bat detector kit... I can't share much about this particular recorder yet. What I can tell you about it is:

• I've only assembled 2 so far; of which only one was successful (mea culpa).

• It uses SMD components (tiny, surface mount components). I will point out, that having only minimal experience with these parts before - delving into the technology has been fun! It's nice to know that all those years of building scale models wasn't for naught!

• It's a stand alone/static recorder type. Very much like The Audiomoth.

• I've got the parts to build three more.

But I'm not at liberty to discuss it here (yet). If and when the developer of the unit gives me the green light, I will post about it here profusely...but not until then (I hope you're reading this, Phil!).

Generally speaking, it's been a case of "Necessity being the mother of invention" here lately... Well, sort-of. That's the best analogy I can think of at the moment.

I've been very interested in obtaining some (decent-quality) recordings of my local wildlife. So, again, I've been looking very closely at the currently available devices which would enable me to do this. After some early attempts with the Zoom H1n, I thought it would be ideal, to write a post, comparing the static recorders (under a certain price point). This is still in the early stages, but in progress.

So, Wildlife Acoustics were kind enough to send me a Song Meter Micro, to help in my quest - and in my comparisons of - Static (primarily non-bat), recorders. As many of you are already aware: The Song Meter Micro is a very versatile, and easy to deploy unit. It's also very affordable.

So, in other news - I will be presenting a live webinar review of The TeensyBat 4.1 DIY bat detector kit; for BatAbility Club. This will be on the 16th of January. And viewable by club members (both live, and later in recorded format).

The TeensyBat has turned out to be not only unique; but very capable and versatile. I've also purchased one of the additional (round) DIY Mics, sometimes available on the TeensyBat site (Parts section). I'll be building an external microphone with it, to be tested with the TeensyBat, and other recorders. Hopefully, to include one of the latest AudioMoth units as well! 

I'll eventually be sharing the results of my tests, here on the blog. As well as a fully detailed review of The TeensyBat itself.

There will be a good assortment of topics and discussions here soon (mid to late January) and I hope that you'll find them interesting & enjoyable!

So, until next time:

Happy New Year! And happy bat detecting! 

Review: The SSF BAT3 Bat Detector by MeKV (Germany)

Review: The SSF BAT3 by MeKV, sold by All About Bats (in Germany).

The BAT3 is full-featured heterodyne bat detector.

So, firstly: If you reside in Germany, Switzerland, or Europe in general - You might be interested to know, that ordering one of these detectors is a fast & easy process. And if you're in Germany or Switzerland, you are allowed to order it with the official battery.

Product Description - The SSF BAT3 is made by the same folks who manufacture The SSF BAT2, which is a well-known bat detector - which I reviewed Here (on this blog).

Packaging - I ordered The SSF BAT3, with all the options; and it all arrived to me here (in The U.S.) well-packaged, in ~2 weeks after ordering. I ordered mine from all-about-bats.net (in Germany), but they are also available from Veldshop (in the Netherlands).

For anyone ordering one of these units: 

• If you live on the East coast of North America, you can expect the delivery to take approximately 8-14 business days (not counting Sundays).
• If you live in Europe, you'll only wait a fraction of that time - Probably about 3 days, would be my guess (mostly likely as short as 1-2 days!).

Via DHL from Germany to The U.S.

Unboxing...Black Nylon carry case (w/ belt loop); the

included user manual is in the German language.

4GB MicroSD card, USB cable, European AC power adapter

The BAT3 wrapped in protective wrap.

This unit is small! And this happens to be one of the things which I really like about it. It's also very lightweight (125 grams).

Removing the protective plastic from the screen.

Look how small and cute it is!

The (optional) carry case features a belt loop, and very secure Velcro® flap.

The unit is provided with: The attached, adjustable wrist strap; a full printed manual in German. I had printed out the English version of it (even before it arrived!)

Link to the User Guide PDF, in English:

The SSF BAT3 - All About Bats (English)

I've been able to find The SSF BAT3 for sale from two online dealers:

All-About-Bats (in Germany)

-and-

Veldshop (in the Netherlands)

As already stated, The SSF BAT3 is an active, heterodyne bat detector. It may be used as a tuneable heterodyne, or as an Auto Heterodyne (AKA the "Auto Bat" feature).

From the beginning, it's hard not to like this detector! Upon powering up and checking/testing this instrument: You will notice the incredible sensitivity and range; as well as the precision of it's volume control. These are the two main features which I noticed first.

The microphone utilized is the small electret model # FG-23629, made by Knowles.

I really like it's features! This bat detector is also fairly easy to use.
Of course, you have full control of tuning the heterodyne portion of the unit, via the Up and Down arrow buttons on the front (in 1kHz steps).

First impressions were good! The frequency range of this unit, is 15 to 150kHz. I really liked the sensitivity of the unit, and the audio output of the speaker is very good: Plenty of audio for everyone to hear on a bat walk.

The SSF BAT3 is a factory-assembled, ready-to-use detector. So, I got to charging the battery immediately. 

Note: Again, if you live outside of Europe, you will need to purchase your (Nokia-compatible battery separately).

The typical battery life is stated as being about 3-6 hours. Initial charge time for the new battery (before 1st use) was stated as 8 hours in the user manual. I was able to achieve full charge in about half that time...

One of the reference screens available - Shown in German here 

(I have mine set to English).

When I went to insert the micro SD card, the little metal door came right off in my fingers - Yikes! I got it back on it's hinges, and locked the SD card in place. 

It has a few neat little informative "pages" (screens) about bats, bat calls, sonograms, etc., - Like a "micro encyclopedia" (for lack of a better description). I'll share pics of these screens below. It's available for viewing in both the German or English language. Something to look at during lulls in bat activity.

Just a couple of examples shown above

All in all, I like it. Mainly because it packs so many features into such a tiny package. Having purchased the belt loop carrying case, means it's easy to have with you, if you expect to be anywhere near bats.

With 2 button pushes to power on, it's very easy to use. Requiring the user to press two separate buttons in succession, prevents accidental powering on.

This little heterodyne detector would be ideal for beginner or intermediate bat chasers.
It would be an excellent choice for anyone leading a bat walk; and does produce nice sounding heterodyne audio.

Short videos of The SSF BAT3 may be seen on my YouTube channel.

I found this unit to be fairly accurate in what it detected, and the resulting spectrograms were very good. I would occasionally print them out, on 8.5x11" Letter size paper: The spectrograms look good, and you can write your own notes on the printouts. Either of the ("print screen") styles shown below, may be copied/pasted/e-mailed or sent directly to your printer.

While using The BAT3Viewer App, you can toggle between 3 color choices for ths spectrogram legend: Blue(s) as shown below, Green(s), and Red(s).

An example of a "Sonogram" (spectrogram)

produced by The BAT3Viewer App

This is the .BMP screenshot feature available

when using The BAT3Viewer App

Pros:

• Uses a nice, sensitive, electret microphone element. It seems to perform as well as some other pro-level detector microphones. 
• It's tiny! If someone were in the market for a James Bond-sized/secret/full featured bat detector, this would be it.
• It has the potential to be plenty loud - enough audio, even for a large-sized group to hear on a bat walk.
• It has a built-in torch - white LED. Which features an auto shut-off (I would have liked it a little brighter).

Cons: 

• It seems to be based on a Nokia cell phone platform. It's not very robust, in fact I might describe it as closer to delicate.
• The included wrist strap would be a must! If you drop it on a hard surface, damage will occur.
• It's only a heterodyne detector, although it does have an Auto-Het tuning feature.
• The door which holds the micro SD card, is the most delicate one I've ever encountered. Use caution.

Like The SSF BAT2, the unit covertly uses a built-in Frequency Division circuit to produce spectrograms.

Green

Red

All things considered, it is a very nice heterodyne bat detector, with useful features. If I discover any other information or notes to add, I will update this review as needed.

The next bat detector to be reviewed here, will be The Teensybat 4.1 (DIY) Kit; which comes to us from The Netherlands. 

Until then,
Happy bat detecting!