Review: The uMoth (AudioMoth) From Open Acoustic Devices

Review: The uMoth (AudioMoth) From Open Acoustic Devices

FYI: A full, webinar (review) of The uMoth was presented on The BatAbility Club (on 9/11/2023). This detailed discussion (1+ hour) is available for viewing anytime, to members of the Club (individual memberships are only £30 per month).

The uMoth is the worlds smallest passive bat recorder. It is a miniaturized version of the well-known AudioMoth, passive/static wildlife sound recorder. Just like the larger (original) AudioMoth unit - The uMoth is not only able to record ultrasound, but sounds in the audible range as well.

Stock Photo - Back/Microchip view of The uMoth.

This brings to mind The AudioMoth Live desktop App, and the fact that the heterodyne detector simulator, tunes down to 12kHz. 

Let me point out straight away, that Open Acoustic Devices is a non-profit organization. There are two firms who manufacture these devices designed by The Open Acoustic Devices Team. They are: GroupGets and LabMaker.

Front of The uMoth - Where the microphone hole, MicroSD card slot, Battery connector, Main switch, and MicroUSB connector reside.

The current price(s) from the manufacturers (at the time of this writing) are:

GroupGets - $99.99 + Shipping

LabMaker - Currently not available (sold out)

Packaging - The uMoth arrived (rather quickly) to me, here on the East coast of The US, from England. It arrived well-packaged & protected. See below - Inner box, after removing from external, brown padded envelope: 

The uMoth PCB, packed with Silica gel

(cute business card is visible through static-proof bag).

The uMoth measures 32 x 24mm and the PCB itself weighs just 5 grams (without battery).

It's intended to be used on certain animals as well. The fact that it's so small and light, makes it an excellent candidate for attaching to animals (especially large mammals); providing Ecologists/Biologists with dynamic sound recordings. Adding a very interesting facet to their collection of sound files.

Photo above shows: The uMoth, USB based battery charger, and an enclosed battery. Photo provided by Open Acoustic Devices.

Features - As per Open Acoustic Devices' site: 

• Silicon Labs Wonder Gecko microcontroller:

– 48MHz 32-bit processor 

– DSP instruction support and floating-point unit 

– 256kB Flash 

– 32kB RAM plus an extra 256kB of external SRAM 

– For full details of the Wonder Gecko microcontroller please see the Wonder Gecko reference manual. 

• On-board analog MEMS microphone, Sensitivity -18 dBV/Pa, 63 dBA SNR, 10Hz to 192kHz 

• Sample rates up to 384kHz 

• Micro-USB B port for power, configuration and for reprogramming the Flash 

• 2-pin JST-PH header for connecting external power supplies (3.6V to 6V) 

• 6-pin 2.54mm pitch header for multi-function 3V General Purpose I/O (GPIO) 

• 6-pin 2.54mm pitch serial wire debug port 

• MicroSD card connector compatible with up to 1TB capacity

One of the reasons why I became fascinated with The uMoth: It's ability to comfortably fit into an empty film pot! With battery! Photo provided by Open Acoustic Devices.

Yes - It's in there, with MicroSD card inserted, and battery (it's sitting atop Page 2, of the 7-page datasheet). 

The uMoth has been designed to not only be incredibly small, but also versatile. Those who know their way around single board computing devices (like the Raspberry Pi or Arduino) will be happy to see the flexibility offered by The uMoth. Several available contact pads, offering: GIPO/logic states, a 3v power output, and other geeky goodness, provides plenty to keep an evil genius satisfied.

If at this point you're wondering "what is he going on about?"

Have you ever wished that your coffee maker could turn on at the first fly by of a bat? Well, it wouldn't be out of the question using this circuit board as your starting point...

                        

                                                            

GIPO pads are clearly visible on the circuit board.

I found several tiny screwdrivers ideally sized for the turning the rotary switch.

                                                         

Here is a link directly to the Datasheet for The uMoth. When you do order a battery (or two) for it, make sure that it comes equipped with the correct size JST-PH connector.

It just so happened, that one of the batteries I ordered (from Amazon) came with everything needed to get the battery attached to The uMoth. As well as an excellent printed page, describing all you need to know about JST connectors:

                                                     

This one included a small length of heat shrink tubing, 2 connectors (w/red & black leads), and a convenient fold-out providing you with all you need to know about JST connectors.

An assortment of JST connectors.

       

You may learn more about JST connectors here.

To give you an idea of what your typical batteries will look like:

The first two are ideal sizes, for a good balance between small size and performance. The extra small (100maH) one was used for experimental enclosures (paper clip for scale).

I cut and soldered the red & black wires (into their correct places) and used my own heat shrink tubing. However, you do not need to go that route. For someone not keen on splicing wires and soldering: The included instructions and something like a ball point pen (or similar) are all that is required to achieve what is needed. 

The uMoth is a bat detector/wildlife sound recorder which may be used in a simple manner (with minimal configuration) - Or, fully customised by specifying times to turn on/record, shut-off/stand-by, trigger by amplitude, trigger by filter setting, and other options.

The AudioMoth Configuration App

Default screen/when first launched - 1970 appears, to help remind you to set the clock.

The next tab is for scheduling.

The next tab, allows you to narrow down which sounds get recorded, by the set-up of filter settings.

The next setting, allows you to set which sounds get recorded, by the set-up of sound duration.

A look at the 'Advanced' tab and it's available settings.

The uMoth would be ideally suited for those wanting the features and performance of the full-sized AudioMoth, in a much smaller package.

Ballpoint pen for scale.

This tiny unit would also be good for those needing to deploy several recorders, quickly, and easily - across a medium-sized area. The uMoth is excellent for attaching to trees. And again, may be attached directly onto medium to large sized animals - providing unique recording opportunities.

Especially, for example if a certain species shares it's habitat closely with the target species.

An example of an quick/simple approach to set-up might entail something like:

• Inserting an appropriate MicroSD card & attaching a recommended battery.
• Configuring the unit via the AudioMoth Configuration software.
• Making sure your time is set - Via Configuration /or Chime App.
• Deploy in desired location.

An example of a more thorough approach to set-up, might include additional steps, things like:

• Configuring the unit to turn on/off at desired times. Up to 4 times in a 24 hour period.
• Setting-up the filter settings.
• Setting-up time duration settings (Minimum trigger duration).

During my extensive testing, I found The uMoth to reproduce sounds very accurately. I found it to offer plenty of sensitivity, with very little self noise. 

Just to outline what each of the three switch settings provide:

• USB/OFF

Consider this a starting point: With a USB cable connected, it allows you to: Set the on-board clock, configure scheduled recording(s), and apply new firmware.

When not connected to a computer, it serves as an Off switch.

• Custom

If configured (recording schedule has been set): The uMoth will start running it's configuration. In order for this to happen, the clock must be set - Either during configuration, or with a chime from your smartphone.

• Default

This will cause The uMoth to start recording continuously. It will use whichever sample rate, and gain level is configured. The clock doesn't need to be set.

Below, are just a few short spectrograms, made using The uMoth, and using Kaleidoscope Pro software, from Wildlife Acoustics:

Eptesicus Fuscus - Big Brown Bat

Eptesicus Fuscus - Big Brown Bat

Lasionycteris Noctivagans - Silver-Haired Bat

Some additional features:

• EFM32 Gecko processor

• Capable of recording at sample rates up to 384kHz

• Records uncompressed WAV files to microSD card

• Powered by a two pin JST-PH connector 

• Can be used with 3.7 V - 6 V batteries

• Analog MEMS microphone

• Analog pre-amplifier with adjustable gain

• Measures just 26 x 36 mm

• Configurable USB interface

• Onboard real-time clock keeps track of time in UTC

• Exposed header for GPIO expansion 

Pros:

• Excellent, sensitive, low-noise microphone.

• High-quality, detailed recordings.

• Very small size.

• Long battery life versus size of batteries (LiPo).

Cons:

• Configuration isn't as easy as other (more expensive) static recorders.
• Cannot always be ordered immediately (may need to join a campaign).
• The clock must always be set: Either via a few clicks, while connected to PC, or via the smartphone chime app.

Again, the only way to order this device, is through either of the manufacturer's respective web sites:

GroupGets - $99.99 + Shipping

LabMaker -  Not available (currently sold out)

I've also been (slowly) working on creating videos, and posting them on my YouTube channel. I would greatly appreciate it, if you would visit, and please consider subscribing. Not for the reason why most YouTubers ask for you to "please subscribe, and hit that button...and bell" and whatever else - No, I'm only asking, for the sheer desire to share information.

As it has always been one of my main goals, from the very beginning with this blog - For it to be a free, non-profit, ad-free place - where I help get the word out about the latest and greatest bat detectors. It's basically the only place on the Web, where you can get completely honest, unbiased, reviews of bat detectors (and associated equipment).

So, again, as for my YouTube channel - I have no expectation of ever achieving 1,000 Subscribers. And that's totally fine.

However, if you know of anyone who might find my (short) videos of interest, please share! It would be nice to have around 100 subscribers one day...

Thanks! 

I've also just started to create simple videos, which allow me to share the actual sound recordings produced by the different bat recorders. There are a few there (so far...) of recordings from this uMoth. 

I may as well mention...My Twitter: @batdetectors

And my Instagram: batdetectors

I'll also take this opportunity to mention, that we've talked about doing a live webinar/presentation review of The AudioMoth USB Mic. It is tentatively planned for The BatAbility Club, in November. As always, it will be a live, detailed, presentation - with opportunities for Club members to ask questions, etc.

This brand-new USB Mic, is the very latest device just developed, by the Team at Open Acoustic Devices in the UK. As far as I know, I'm the only one outside of The Open Acoustic Devices Team, to actually get my hands on one! They aren't available for sale yet. I'm happy to state that I've had plenty of time to test this new USB Mic:

Firstly, I really like it!

And, secondly, I did post a written review of it here on the blog.

 

It is a versatile USB Microphone because it can be attached to either a laptop or smartphone. 

When it does become available for purchase, it will be affordable, at or below the $100 mark...

Until next time,

Happy bat detecting!