[/heading][divider line_type=”No Line” custom_height=”4″][toggles accordion=”true”][toggle title=”Q: Will SonoBat work with my AnaBat detector?” color=”Default”]
A: No, the AnaBat uses zero-crossing, which employs a different high-frequency sound conversion principle than full spectrum detectors. Zero-crossing does not acquire sufficient signal information to render full spectrum, high-resolution sonograms.
[/toggle][toggle title=”Q: Will SonoBat work with *.wav files generated from a frequency-division bat detector?” color=”Default”]
A: A divide by ten frequency division essentially discards all but 1 in ten parts of the data and prevents the high resolution analysis that is the foundation of the SonoBat approach. You can use SonoBat to inspect frequency division audio signals, but you will get a very smeary-looking image because you only have 10% of the signal resolution of a full-spectrum signal. So the answer is yes, you can use SonoBat with frequency division, but how well you could use that information for bat identification will be limited, you will have a lack confidence for anything more than sorting of the most basic call characteristics, and you will not have access to the subtle discriminations that SonoBat can support with full-spectrum data.
[/toggle][toggle title=”Q: Aren’t time expansion bat detectors more expensive than zero-cross or frequency-division units?” color=”Default”]
A: Not necessarily. There is a greater variety of time expansion detectors available than zero-crossing detectors, some of which have special features and high prices. But a basic unit such as a Pettersson D240x will yield excellent results and has a comparable cost to an AnaBat detector together with the requisite ZCAIM unit needed to interface with a computer. No extra interface unit is needed to use a time expansion detector with SonoBat (see below). Most of the recordings displayed on these web pages and in the SonoBat demo were made using a similar Pettersson D140.
[/toggle][toggle title=”Q: How can you power Pettersson D240x detectors for longer periods than can be supported by a single 9V battery?” color=”Default”]
A: The D240x can accept 12V external gel cell battery, attached to a matching 9V connector (with appropriate polarity; positive-male / negative-female) connected to the D240x with an in-line 1Amp fuse on the positive line from the battery to protect the D240x. A recorder and solar panel charger can be integrated as well. A D240x draws about 20mA of current. For more information see: http://batterystuff.com/batteries/
[/toggle][toggle title=”Q: Can I use a Pettersson D240x as a passive recorder for multi-night monitoring?” color=”Default”]
A: Check out the following link on how to setup the D240x with a Samson Zoom H2 recorder:
These instructions provide for a single night of recording, but if you want you can take it further. The Zooms apparently accommodate larger CF cards than they say. 8 GB cards work fine, and they would probably accept 16 GB, although 8 would likely get you through at least two weeks of recording. You would need to supply external power to the Zoom, and it has a jack for that: 9V (peculiar, as it runs off two batteries = 3V, so there must be some tolerance with its voltage supply); but do note the polarity. You can power the D240x directly from a 12 V supply (Pettersson-approved). Attach the power supply to the D240x using a 9V battery clip, making sure to get the correct polarity as it would come from a single 9V battery.
You can not schedule the Zoom or D240x to cycle on or off so it stops recording during the day and resumes the following night. However, it can be accomplished by using programmable lawn irrigation timers. These take a single 9V battery that lasts for months. Take the signal from the timer and use that to control a relay to open and close the power to the D240x. When off during the day, the Zoom gets nothing to record, and keeping power on the Zoom maintains its clock setting. When power returns to the D240x it goes right back to operating as set.
For an alternative, higher tech approach, you can use Binary Acoustic Technology FR125 programmable recording units. They can be set up to trigger from D240x units. But, by this point, you’ve invested in nearly $2,000 worth of equipment, so you might as well purchase a dedicated, all-in-one, full-time autonomous recorder, like the Pettersson D500x, and keep your D240x for recording high-quality voucher calls.
[/toggle][toggle title=”Q: Can a D240x be used for a mobile transect?” color=”Default”]
A: Event though time-expansion D240x detectors only are in active recurring mode 10% of the time, because 90% of the time is spent expanding and saving the TE recording (i.e., a 1.7-second recording takes 17-seconds to process and save), operationally this doesn’t result in many missed bat passes unless bats are triggering recordings at intervals of less than 1.7 seconds (the standard setting for passive monitoring) they won’t be missed while the unit is processing data. Unfortunately, results are far more disappointing when using a D240x for a mobile survey. Mobile surveys tend to have a lot more noise that trigger recordings. That does not affect a real time recording device like a D500x as it can get right back to recording after a noise-triggered event, but with the D240x that spends ten times as long offloading the data just ends up missing too much.
[/toggle][toggle title=”Q: How can I protect my detector from rain if I leave it out overnight, or for days at a time?” color=”Default”]
A: Most detector microphones are “weather resistant” and will not be damaged by rain. It is especially important to orient microphones so they do not collect water on the sensitive membrane. Wet microphones will not faithfully record high-frequency sound until they dry out. Orienting microphones slightly below horizontal will prevent water from pooling on the membrane. (This includes moisture from condensation, dew, or fog.) Windscreens are effective, but at the expense of sensitivity. Other weatherproofing devices (tubes, reflectors, enclosures) negatively affect call quality, especially with full-spectrum detectors and therefore should not be used. Unfortunately, bat the detectors themselves are not as resistant to moisture. Using an external microphone on an extension cable and housing the detector in a weather proof box is a good solution. For added protection, the microphone and cable attachment can be shielded by a piece of angled flashing to protect connectors from moisture damage.
Lars Pettersson assures us that the external mic is essentially weatherproof so long as you do not point it up so that it can collect water. So pointing horizontally should be fine. In fact, Pettersson says the only problem with vertical would be that you can’t hear through the water; he did not seem at all concerned that the water would hurt anything. For more information see the Deployment Tips in the Resource section on this site.
[/toggle][toggle title=”Q: I’ve followed the instructions in the User’s Guide for setting the gain on my computer’s sound card, but I still can’t get the signal low enough to avoid overloading the signal level. ” color=”Default”]
A: (This is largely a Windows operating system problem) First, make sure that you have enabled the advanced settings for your microphone volume settings, and checked these advanced settings to disable any microphone boost settings, e.g., +20 dB gain. If that doesn’t remedy the overload, you may have a laptop with an exceptionally sensitive sound card, and you will need to use an attenuation cable between your detector and computer. You can get one from:
Trew Audio, Inc.
220 Great Circle Road
Nashville, TN 37228-1798
voice: 615-256-3542 or 800-241-8994
Trew Audio will make a custom cable for you. Request a 20 dB attenuation. Just ask for the same type of cable that Joel Tigner ordered.
[/toggle][toggle title=”Q: How do I add a new SonoBat regional classifier to my current suite of SonoBat programs?” color=”Default”]
A: SonoBat 3.2.x regional classifiers are available in “zip” format from this website for download. Simply unzip the file (if needed) and move the SonoBat 3.2.x.exe (or SonoBat 3.2.x.app) file into the SonoBat Suite folder in your Program files (or Applications) so that it resides with all the other SonoBat 3.2.x.exe (or *.app) files and utilities.
To create a “shortcut” to launch the new SonoBat classifier on a PC, Select the appropriate *.exe file recently moved into the SonoBat suite and Edit —> copy or CTRL-C, then go to the Start Menu, select the SonoBat Suite Folder, right click to open it, right click in the folder and Edit —> paste or CTRL-V to paste the shortcut. Then go back to the Start Menu and open the SonoBat Suite folder, and the new SonoBat 3.2.x classifier should be there. CTRL-clik to move it to a preferred position.
To create a “shortcut” to launch the new SonoBat classifier on a Mac, navigate to Applications in a finder window, select the SonoBat suite, find the new SonoBat 3.2.x classifier.app file and drag it to an appropriate position on your dock.
[/toggle][toggle title=”Q: How can I use SonoBat and full-spectrum bat detectors in public presentations about bats?” color=”Default”]
A: SonoBat can add a great enhancement to bat talks. Go to the Resources page, and follow the link there for suggestions.
[/toggle][toggle title=”Q: I’m getting so many noise files with my Pettersson D500x detector. How can I tweak my settings to avoid this?” color=”Default”]
A: Set the gain and trigger settings on your detectors dependent upon your goal; whether to sample for activity or just confident presence/absence. I don’t like to mess with lots of low quality signals if I just want to get the best files for knowing what’s around and for that purpose I use a gain/trigger combination of 80/200. That seems to work well, but will require a bit of experimentation for different habitats. The higher trigger setting should also make it less sensitive to triggering by noise. Check all the hardware in the mount around the mic and the pole and connections. If anything creaks or slaps it could generate signals that trigger the detector. To get more activity monitoring (but many more lower quality recordings), reduce the trigger setting from 200 to perhaps 120 or 80.
Of course your best solution would involve recording away from the insects or during a season when the insects don’t makes as much sound! This sounds impractical, but should be considered for longer term planning. This complication affects acoustic bat work in many parts of the world and we also suspect that it must also affect the bats, too.
As a compromise the best that you can do involves reducing the trigger sensitivity of the detector. Also, you will gain some improvement by locating the microphone as away from vegetation and the ground as you can to gain some distance from the insect sound sources and get it closer to the bats in the air that can trigger it. Example recording settings:
Gain: 70 or 80 (I typically use 80, but up to 120 when I want to get quieter signals)
Trigger level: 200 (I use 120 in quiet environments)
Trigger Sensitivity (found in the user profile menus): very low (I use medium in quiet environments)
Note: the somewhat mis-representationally named Sensitivity setting controls the duration of the sound that triggers the detector. By setting it to very low you avoid short duration sound sources (like rain drops) from triggering the detector, but “longer” ones like 2ms bat calls will still trigger the unit.
[/toggle][toggle title=”Q: What is Sampling frequency, and what is the best setting for recording high-quality calls?” color=”Default”]
A: Wildlife Acoustics bat detectors allow sampling frequencies of 192kHz, 256kHz or 384kHz. Binary Acoustic Technologies detectors allow sampling frequencies of 250kHz, or 375kHz. And Pettersson detectors allow sampling frequencies of 300kHz, 500kHz, 750kHz or 768kHz.
What does this mean, functionally? Digital sampling takes snapshots of a signal at regular intervals, equivalent to the sampling frequency (e.g., at 500kHz sampling frequency, digitizing the signal occurs 500,000 times a second). But it can’t “see” what happens between those snapshots. According to digital sampling theory, detectors can only resolve real, i.e., non-aliased, sounds up to one half of its sampling rate. This limiting frequency is called the Nyquist frequency. So, for Wildlife Acoustics detectors, that means it can only sample bat calls up to 96kHz, 128kHz, or 192kHz; Binary Acoustics Technology detectors allow resolutions up to 125kHz or ~180kHz; and Pettersson detectors allow resolutions up to 150kHz, 250kHz, 375kHz or 384kHz.
Capturing fully formed bat pulses, with the full upper frequency portions is often essential for species ID, and especially for capturing harmonics. Plus, when sampling a too low a rate, aliasing can occur, creating artifactual harmonics. This can interfere with the original signal and confound analysis. For example, recording bats out west with Wildlife Acoustics detectors at a 192kHz sampling rate can create spurious identification results for Myvo as the aliased signals resulting from a low sampling rate can appear like upsweeps typical of Myvo, when in fact the recording may actually belong to one of 6 other 40kHz Myotis species. Therefore, to render accurate recordings, you should always use the highest sample rate possible, or choose a detector that allows for the highest sample rate.
[/toggle][toggle title=”Q: What is the best method for obtaining voucher calls using SonoBat and/or bat detectors in general?” color=”Default”]
A: There are several techniques. One of the best is to use a Zoom H2 connected to a Pettersson D240x for manual tracking and reference call collection that can be off-loaded call-by-call to a laptop int he field running SonoBat using the AutoRecorder Utility. To set up the hardware and software properly, follow the directions available at the following link:
. . . and change the light setting to ON and after triggering a call, watch the seconds on the Zoom and when it counts up to 16 (or 33 for 3.4 sec) and click the StartStop button to end the playback and prevent recording the D240x button sound.
Other detector/netbook configurations using Binary Acoustics Technology equipment allow for realtime viewing of the bat call and manual tagging of using voice notes or text headers. The new Pettersson D500x FD allows for a realtime audio-output of the recorded signal. Switching user profiles to a 44.1kHz sample rate with a manual trigger allows for recording voice notes after each recording. The Pettersson D1000x is a higher quality, all-in-one recorder also with voice note capabilities. And, the new Wildlife Acoustics EchoMeter Touch with an iOS device and EchoMeter application provides similar realtime viewing and tagging capabilities.
[/toggle][toggle title=”Q: How many voucher calls is enough to capture the repertoire of a species?” color=”Default”]
A: Most researchers who record voucher calls keep moving the number up as we keep finding more and more variety and unexpected vocalizations. These days we would consider 30 calls per species to be too low by an order of magnitude. For some species we would want more than that, for other species we might feel fine with less. The number varies both by consistency of calls represented in the repertoire of the species, and its acoustic distinctiveness from other species.
Some citations to support this include:
Duffy, A.M., Lumsden, L.F., Caddle, C.R., Chick, R.R., Newell, G.R. 2000. The efficacy of Anabat ultrasonic detectors and harp traps for surveying microchiropterans in south-east Australia. Acta Chiropterologica 2(2):127-144.
Waters, D.A., and W.L. Gannon. 2002. Bat call libraries: management and pote ntial use, p. 150-157. In: Brigham, R.M., E.K.V. Kalko, G. Jones, S. Parsons, H.J.G.A. Limpens (Eds.) 2004. Bat Echolocation Research: Tools, Techniques, and Analysis. (Proceedings of the Bat Echolocation Symposium and Tutorial April 15-17, 2002) Bat Conservation International, Austin, TX. 167 pages.
[/toggle][toggle title=”Q: I have a SMX-US microphone and want to make it more directional should I invest in the SMX-horn or can I adapt a parabolic dish that I use for bird recordings to this microphone instead?” color=”Default”]
A: If done properly it should not distort the signals. However, when you reach further through the air you will enhance the differential frequency attenuation effect of propagated ultrasound. That is, higher frequencies get more attenuated than lower frequencies. So I suspect you would detect bats at greater distances, but your rate of effective species ID may diminish from the selective loss of higher frequency content..