Bats are animals I became a little bit obsessed with after travelling around Australia in 2023/2024.

My first time seeing and recording the larger Flying Foxes was in Harvey Bay, QLD then almost daily when I lived in Sydney, NSW. There is a large colony that live in Centennial park roughly 20 mins bus journey from where I lived. Every evening they would fly over the city in search for food, it was great!

Click play on the video below to hear the Flying Foxes in Sydney!

Unfortunately we don't have the big ol'flying foxes here in the UK, but we do have a wide range of smaller bats. One particular species called the Common pipistrelle has made a roost in my garage.

What's the difference between Flying Foxes and UK Bats? 

The main difference is the fact that bats in the UK rely on echolocation to find food as opposed to using sight and smell like the Australian Flying Foxes. This poses a fun challenge when recording UK bats as the sounds they make for echolocation are ultrasonic.

What is Ultrasonic Sound?

Ultrasonic sound (Ultrasound) is sound energy with a frequency above 20kHz. Higher than the upper limit of the human hearing range which maxes out at around 20kHz. Generally, the older you get the less frequencies you're able to hear.

Luckily for me, I didn't completely fry my ears when I was learning to play the drums as a teenager so I'm able to faintly hear clicking coming from the Common pipistrelle's as they fly out of the garage in the evening to hunt.

How do we record them?

Having around 5-6 of these bats roosting at home got me excited to record them, as I can pretty much guarantee I’ll see as few of them every evening.

But to record Bats, you need a microphone capable of recording ultrasonic frequencies. The LOM MikroUcho and the little Ultrasonic Horn attachment are capable of doing that. 

The MikroUcho is a very sensitive, small Omnidirectional microphone with the ability to record really high frequencies. The Ultrasonic Horn attachment amplifies frequencies in the ultrasonic range, so in theory it'll make recording the bats easier. (Cheers Jonas for sending the mic and horn out to test, I've already captured some cool recordings!)

Sample rate

To record the bats we also need to change the sample rate on the audio recorder to 192kHz. This allows the recorder to record sound frequencies out of the human hearing range and it's crucial for when we pitch shift the recordings to identify the bats.

How do you identify the bats?

One way to identify bats is with specialist bat detectors like the Magenta Bat 5 detector. This was actually one of the reasons I ended up reaching out to to Jonas about bats in the first place, I saw him using one in an Instagram story. But if you want to figure out how to identify bats from your recordings without one, it's pretty simple.

In your editing software (in my case Cubase) you simply pitch shift the recordings DOWN -3 Octaves or -36 Semitones. This is what those specialised Bat detectors do in real time.

Here's a neat little table which tells you what echolocation frequency each UK Bat species communicates in:

One thing to note is that the frequencies above are what's shown on the bat detector. So of you recorded them, you would need to pitch down -3 octaves / -36 semitones to be able to cross reference your recordings with the bat chart.

Lets hear some RAW recordings

The following recordings were captured using the MikroUcho + Ultrasonic Horn mounted on a Radius mount, recorded into a Zoom H5studio at 192kHz. These are all unedited, it’s what you hear with your own ears.

Raw Bat Recordings (6 different recordings)

Lets hear the pitch shifted recordings

Now these are really cool! It also let me identify TWO different species in the garden. The higher pitch recordings are Common pipistrelle's and the lower pitch recording is a larger Noctule bat. Which must have made it's way over from a nearby woodland as they prefer to roost in tree cavities or old woodpecker holes.

Common pipistrelle (Pitched Down)

Noctule (Pitched Down)

Echolocation is LOUD!

I was initially confused when I first listened back to the recordings as one recording in particular sounded as if it overloaded the microphone. On the timeline it didn't look like there was anything particularly loud and I was recording in 32bit so the H5studio's internal pre amps weren't overloaded. 

I later learnt that bat echolocation can get to a whopping 110-140 dB. It's just that we can't actually hear it with our own human hearing. The MikroUcho microphone has a Maximum input pressure level: ~115 dB SPL so I’m guessing the bat must have exceeded that.

To put that in perspective, 115 dB SPL is the equivalent to a loud concert or a chainsaw. That's very loud. So to clearly see the bat exceeded that is impressive to say the least.

On the topic of Echolocation

It's kinda on the same topic but a project I’d like to explore in the future is recording Sperm Whales. Researching more about how bats use echolocation I went down the rabbit hole and learnt that the clicks Sperm Whales use for communicating can get as loud as 230dB+. That's truly mental! 

Hearing about this really made me excited about the possibility of recording them one day with hydrophones (underwater microphones like my Aquarian Audio H2d). So if you know any researchers, gimme a shout! 

What's next? 

After chatting to Jonas (founder of LOM) about the recordings I captured I'm going to experiment a little more with the microphone, ultrasonic horn and how I can process the recordings for sound design. 

The pitched down bat recordings would be really fun to use as alien or creature sound effects. There's a lot of character and variation in the sound which would work well if they were performed on a keyboard using a sampler. Slowing down the sounds as well as pitch shifting them.

Here's an example of one bat recording slowed down as well as pitch shifted using a sampler. I've also used a plug-in called Guitar Rig 6 to add some delays, filters, phasing and reverb. Quite a spoooky vibe.

Common pipistrelle Bat on a Sampler

There's a lot more I can learn about our UK bats and I'm excited to record, experiment and share the process with you along the way. Cheers for reading. 

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