Which bat detector?

Recent advances in bat detector technology mean that a lot of the advice on the internet is out of date, hence this is our up-to-date (Dec 2025), tried and tested, advice on how to choose the right bat detector for you. On this page we have:

It is very possible to watch bats without any equipment, especially where they emerge from roosts, or shortly after dusk along well-used bat flight paths.  However as bats echolocation is mostly beyond the range of human hearing, a bat detector is key if you want to hear bats to locate their presence, learn more about them, and be able to understand the differences between species.

Our top recommended bat detectors had not changed for a several years, however new devices with greater abilities at disruptive cheaper costs mean our 2026 recommendations are mostly brand new. (Prices from April 2025)

Summary of our advice for 2026:

Full Detailed List of recommendATIONs:

Bat detectors use several technologies, to enable us to hear ultrasound bat calls that are above the range of our hearing. These are referred to throughout our recommendations, and you can find detailed descriptions of the technologies employed below.

For a naturalist, or interested amateur

If you want to listen to bats out in the field then the Pipistrelle family of devices developed by Phil Atkins from Wiltshire using the RaspberryPi Pico offer advanced features at a market disrupting cost. They also have upgradable software on board, which means new features may be made available at a later date.

To achieve the low cost, they use a very simple construction, hence the long term durability of these new devices is unknown, and may depend largely on use, and original build quality.

Examples of the simple construction include:

  • They do not have an in-built speaker. Instead they use a simple 3.5mm jack for connection to wired headphones or speaker.
  • An open battery pack is glued to the back of the device.
  • A tiny off/on switch
  • The microphone may not be quite as sensitive as more expensive commercial devices.

There are several options in the Pipistrelle family of devices:

  1. For mobile phone/tablet users: The Griff 384kHz USB microphone with a free application will let you see, listen to, record, and view ultrasonic echolocation calls on a colourful, interactive spectrogram display. It can be worn as a credit card sized badge. Currently only available as a self build project (8 to £12 each when building 5). Allow an extra £2-3 for adaptor cable(s).
    Download the apps here:
  2. Best value handheld: The mini PiPistrelle is a auto-tuning Heterodyne and Time Expansion detector, The tuned frequency is announced via a synthetic voice, and LEDs provide frequency range information. It can also be used as a ultrasound mic with a mobile device (i.e. exactly like a Griff).
    It is available assembled at €65 +postage, or as a self build project (£16 each when building 5).

The bat group are running “Build a Bat Detector Workshops” for these, and other devices in the π•pistrelle family.

There are many other basic detectors available, the following are tried and tested Hetrodyne models:

  • Magenta 5 (£116) – this is a good quality, robust, Heterodyne detector.   Simple manual digital backlit tuning, inbuilt torch, and fairly loud volume.   The group has three sets of a dozen of these for loan on Bat walks, and has had superb after sales service from the manufacturer. These devices last for years!
  • The BatBox III D (£170) in various versions was the first, and the “go-to” Heterodyne bat detector for group members for many years.   Manual tuning. Still a solid choice.
  • The Elekon Batscanner (£259), is an auto tuning Heterodyne.  There is also a unique Stereo version  (£319), that when used with headphones reportedly indicates which direction a bat is coming from.

For a committed amateur or Ecologist:

If you want to automatically identify bat species, and record the echo-location calls for later desk analysis a full spectrum detector/recorder like the Echo Meter Touch 2 (£185-£345), used with a phone or tablet is a great tool.

This is a combination of a Ultrasonic microphone that plugs into your phone or tablet, and software that you install.   With this you can listen to, record and view ultrasonic echolocation calls on a colourful, interactive spectrogram.  The software can even suggest the most likely species detected.

There are two current versions of the EMT:

  • Echo Meter Touch 2 (£185) – “Good enough” for most non pros.  For most bats it is similar to the Pro, but is poorer at highest frequencies, and hence it will miss some of the quieter Lesser horseshoe calls.  The group uses these for our Big Bat Counts.
  • Echo Meter Touch 2 Pro (£345) – The industry standard, lower noise, a few more settings, and more sensitive at higher frequencies.
    • The original black Echo Meter Touch, is no longer made, but fell between the two above in price and performance.

In practice results do vary, in general:

  • The software works better on faster, more expensive devices, and the application seems more stable and reliable on iOS (iPhone) devices, than on Android (8.0+)
  • It’s important to check that your device is compatible.
  • Depending on speed of the device, there is some lag as the software analyses the sound from the microphone, hence its difficult to match echolocation with bat behaviour (feeding buzzes etc..)
  • The software can mimic Heterodyne or Time Expansion output to the speaker, but again this can be laggy or broken up sound, and is worse on slow devices.

However having said this, the combination of near real time graphs of frequency detected over time, and auto ID, of species mean that a novice with a EMT2 will usually detect more bats, than a seasoned bat worker of 30+ year experience with their trusty Heterodyne detector.  The book by John Russ, British Bat Calls, is very useful in understanding  the displayed sonograms.

So complete has been the revolution, that there are young bat ecologists starting their careers, that only talk about “hockey stick” , or “staple shaped” calls, and have never heard a bat call via a heterodyne detector.

However many ecologists use both devices in tandem:

  • An EMT with sound off, to detect bats on screen, and check peak frequencies.
  • Then a Heterodyne detector to tune to the specific frequency identified on the EMT, to enable watching of bat behaviour and hear echolocation in real time.

Passive (Static) bat Recorders:

Unlike the handheld devices above, these devices are left out for several nights, and record all the ultrasound they hear for later analysis. Static full spectrum devices like the Song Meter SM4Bat (£1020) are often deployed by professionals in the field unattended for weeks at a time.  But the cost prohibits amateur use. However over the past years a couple of low cost alternatives have become available:

PipPyg

Part of the π•pistrelle family of detectors, this can be bought assembled for €65 +postage, or self-built for £20 each (when building 5+). The PippyG is designed specifically for bat recording, and hence has far fewer configuration options than the AudioMoth making deployment much easier. Testing has shown a comparable recording performance to Audiomoth. The firmware supports the industry standard GUANO format metadata, including Timestamp (local time).

Designed as a AudioMoth “clone”, it is a similar form factor, however the microphone placement and greater depth means it cannot fit in AudioMoth cases, and different DIY cases have to be made. The OBO Bettermann 2000016 Junction Box (75x75mm), is a good base to start from.

AUDIOMOTH

The result of a partnership between Oxford and Southampton Universities has produced the AudioMoth (£80), a tiny, low cost, static ultrasound recorder.   While the AudioMoth produces more noisy recordings, and is not as sensitive as professional equipment, its low cost means it can be deployed in many different situations without worry.

The device has been trailed by the BCT over the past years as part of their British Bat Survey and the development has matured. It is a general purpose ultrasound recording device, and is very configurable. Hence it needs careful configuration to make it suitable for bat recording.

The official case does result in some loss of recording quality, and many AudioMoths are deployed in DIY cases.

Bat detector technologies:

Heterodyne Bat Detection

In Heterodyne bat detectors the bat calls are picked up by an ultrasonic microphone and compared against a selected frequency. This can either be set manually, or auto selected by the device as the loudest ultrasound frequency. A sound is then produced that is the difference between the selected frequency, and the part of the bats call close to that frequency (within 5kHz).

The rhythm and pattern of the bats call is retained, and so, if the bat can be seen, the bats behaviour can be compared to the calls they are making. However the sounds produced by a heterodyne bat detector bear little relation to the actual sound produced by the bat.

Heterodyne detectors produce sounds that are quite melodic and easy to listen to, and you will hear descriptions such as “wet slaps, dry clicks, whipcracks…”.   With experience it is possible to identify some species with heterodyne detectors. See this page for more info.

You can listen to some examples of echolocation call recorded via Heterodyne detectors for most species on our “Bat species in Somerset” page.

Time Expansion Bat Detectors

Time expansion detectors work by storing the call in their internal memory and then replaying it back 10x or 16x slower thus lowering the frequency. The advantage of this system is that the bat echolocation is heard exactly as the bat made it. In the case of 16x time expansion this results in the bat call being played exactly 4 octaves lower than when the bat produced it.

A disadvantage is that when it is playing back a call it can’t listen for other bats, so it may miss some bats. But in the past the main disadvantage was cost, typically over £1000. However this technology is now available on low cost devices.

The group has one Petterson D240x available for loan to members.

Full spectrum bat recorders

These detectors display and record sounds at their original frequencies, i.e. ultrasonic sounds are not converted to a lower frequency in order to make them audible. They offer the ‘best of both worlds’ able to capture sound in the same high level of detail as Time Expansion, but they record in real time continuous monitoring as with Frequency Division (see below for details of these older detectors).   Hence they have become “the standard” with professional ecologists, either handheld, or as “static” devices left out in the field recording for many nights at a time.  The recordings made are then downloaded, and analysed later.

The resulting sound files are very large so these detectors tend to use a triggering system so that recordings are made only when sounds are above certain frequency and amplitude thresholds.

Until very recently these detectors were in the highest price range for detectors (£1000’s) and hence quite rare in amateur hands.   However recent advances in mobile technologies mean there are now affordable options.

A key feature to check is if your desired recorder produces recordings with metadata in the industry standard GUANO format. See this website for the GUANO standards.

Frequency Division Bat Detectors

These older devices detect all frequencies at the same time so there is no need to tune and you don’t risk missing any species. Recordings are made by the device dividing the frequency by a known factor (usually 10x) so the calls can be heard and be recorded for later analysis on computer (usually by a separate recorder).  Sonograms are not as good as those produced by other types.  The big downside is that frequency division is not a pleasant noise to listen to for any length of time and you do not get the pleasing tones of a heterodyne detector.

Common Frequency Division devices are:

  • The Batbox Duet (£276) has been a standard of the bat group members for many, many years.  It has both systems but only the heterodyne signal is fed to the speaker, with the frequency division and heterodyne signals being fed to separate channels of the line out socket.  A separate recording device is used to make recordings for later analysis with free software.
  • The Batbox Baton (£88) has just frequency division and produces sonograms as good as the Duet. It also comes with Batscan software.

The group has a few Batbox’s available for loan to members.

Where to buy a Bat Detector?

Bat detectors are mostly sold online. A web search of “bat detector” will bring up links to the major retailers.   The Bat group has used the following suppliers over the years:

The π•pistrelle family of detectors are available fully assembled and tested from: