Using Wildlife Acoustics SM2 and EM3 detectors with SonoBat versions 2.9.7 and 3.1
 
 
SonoBat SM2 Batch Attributer panel.
 
 

Screenshot of the SM2 Batch Attributer utility. Use this to batch process files or directories of files from Wildlife Acoustics SM2 and EM3 detectors to embed metadata and Wildlife Acoustics frequency adjustments for recordings made with SMX-US microphones.

 
 

Wildlife Acoustics SM2BAT and EM3 detectors produce files with subtle differences in frequency response and signal characteristics than files from other bat detectors such as those from Pettersson or Binary Acoustic Technology. This affects their analysis using SonoBat, particularly when comparing with SonoBat reference files and when using the SonoBat automated. In many cases the signal differences between recordings made with different detectors can exceed the already subtle differences between the calls of some species. Post-processing compensation can adjust the raw files from SM2 detectors to yield comparable results to others when analyzed using SonoBat.

Note: Previous guidance for using SM2 files with SonoBat recommended post-processing SM2 files using the SonoBat SM2 Batch Compensation utility.

We no longer recommend batch compensation. SonoBat versions 2.9.7 and  3.1 performs internal compensation upon recognizing SM2 and EM3 files. See the guidance below for analyzing legacy batch compensated files with SonoBat versions 2.9.7 and  3.1.

Different procedures will apply when using SM2 and EM3 detectors with SonoBat depending upon whether the units recorded wac files or wav files, or whether using SMX-US or SMX-UT microphones. However, with all methods we encourage good data management practice by including metadata notes in your recorded files. Your recorded data can become meaningless unless you know its source, when you recorded it, and other details about it such as the field conditions when recorded, i.e., the metadata of your data. You could add this information one file at a time using the SonoBat file attribute editor. Instead, you can embed metadata to all the files from a single recording session in just one operation using the Wildlife Acoustics wac2wav converter (if recorded as wac files) or the SonoBat SM2 Batch Attributer utility. This embedded metadata will display when you view your files in SonoBat.

Recording settings: We recommend using SM2 units in triggered wav mode . In triggered wav mode, SM2 units also operate intelligently to only write bat-like files to memory and discard noise files (and eliminate the need to scrub noise files in post-processing!). Even though recording without compression, you will likely get more endurance from your installed memory because your units will only record bat pass events, rather than recording continuously as they do in wac mode. If you do use WAC mode, use the highest quality WAC0 setting. We recommend setting the SM2 amplifier gain to 36 dB. The higher setting of 48 dB will increase the sensitivity of the unit, however you acquire the very best call samples from bats that fly closest to the microphone, and with 48 dB many of the close approach calls become overloaded and unusable for species discrimination.

1 Set Compression to OFF. You must have firmware v3.1 or later for triggered wav operation. Max recording durations of 3 or 5 seconds works well for recording full sequences without overlap of other sequences.

Triggered wav operation and post-processing

SM2 recording with SMX-US microphones. SM2 recordings made with SMX-US microphones require post-processing frequency response filtering to optimize their faithful representation of ultrasound recordings. Post-process these files with the SonoBat SM2 Batch Attributer utility to embed metadata notes and enable the SMX-UT filter (i.e., set it to yes). The SMX-UT filter option will apply frequency adjustments provided by Wildlife Acoustics to match the optimized frequency response built in to their EM3 detectors and SMX-UT microphones.

SM2 recording with SMX-UT microphones. SM2 recordings made with SMX-UT microphones already have optimized frequency response adjustments and need no further adjustments. Use the SonoBat SM2 Batch Attributer utility to embed metadata notes with the SMX-UT filter setting disabled, i.e., set it to no.

EM3 recording. Wav files recorded on EM3 detectors already have SMX-UT type frequency response adjustment and need no further adjustments. Use the SonoBat SM2 Batch Attributer utility to embed metadata notes with the SMX-UT filter setting disabled, i.e., set it to no.

Post-processing of WAC recordings

WAC recording acquires a continuous record of the recording session. These files require post-processing to parse them into individual files of bat pass events (call sequences) and conversion to wav file format for analysis with SonoBat.

  1. If you do not already have it, download the most current version of the wac2wav converter (Mac or PC) from the Wildlife Acoustics download page: http://www.wildlifeacoustics.com/downloads.php (Current version 3.3.0 as of this writing.)
  2. Prepare a receiving directory on your hard disk for the files you will convert. Perhaps name it SiteName-Date.
  3. Launch the wac2wav converter. Click on the Add Files… button and navigate to the wac files you want to convert. You may select multiple files. Click on the Change Destination… button and navigate to the receiving file on your hard drive where you want to accept the converted files.
  4. Specify a 3 or 5 Max duration to split the triggered events into separate files. Note: if you do not do this you will get one ginormous and unusable wav file!
  5. Set the Min spacing to 0 seconds so that you will not miss any bat passes that occur immediately after a previous pass.
  6. If you recorded the files using an SMX-US microphone, select the SMX-UT filter. If you recorded the files using an SMX-UT microphone or with an EM3, leave the filter set to None.
  7. Check the SonoBat box and enter any descriptive or field notes to embed as metadata into each file that will display in the note field when opening the files in SonoBat.
  8. Click on the Convert Files button. When done, you can begin viewing and processing the converted files with SonoBat.
  9. You may want to run the files through the SonoBat Batch Scrubber uitility to eliminate noise files, depending on the recording situation.

Viewing and analyzing SM2 and EM3 recordings in SonoBat

Ultrasound recordings made with Wildlife Acoustics SM2 and EM3 detectors have subtle differences in low level noise compared with other detectors. You can increase your throughput of identified calls if you adjust your SonoBat preference for acceptable call quality downward from the default setting of 0.80 to 0.70 to compensate and enable the consideration of more calls.   SonoBat quality preference settings
Use caution to avoid too many low quality calls to pass through as acceptable as that may compromise correct classification with SonoBat 3. To increase the recognition of sequences for tallying bat passes, reduce the acceptable quality to tally passes from the default setting of 0.20 to 0.10 or perhaps as low as 0.05. The ambient noise and acoustic conditions will affect how low you can adjust this setting and avoid errant tallies of non-bat signals. If uncertain of how this setting will perform with your data, run some test batches and inspect the results to guide your selection. Most users will probably want to err on the side of caution and use a higher value that avoids tallying any non-bat signals.
     

SM2 aware button.

Filter and preemphasis settings when SM2 aware.

  When SM2 aware, SonoBat will recognize files with sampling rates of 196 and 384 kHz as originating from Wildlife Acoustics SM2 or EM3 detectors. SonoBat will then perform internal routines and adjust settings to optimize processing of these files. When SM2 aware, SonoBat will set the frequency filter to unfiltered and the preemphasis setting to none upon opening any files with sampling rates of 196 and 384 kHz. Note that if you later process files from other detectors, you should set those controls back to their default settings of 5 kHz, medium, and filter mode to autofilter if you prefer.

Viewing and analyzing legacy SM2 and EM3 recordings processed with SM2 compensation

With SM2 aware enabled, SonoBat versions 2.9.7 and 3.1 will automatically detect and perform internal compensation to optimize processing of native SM2 and EM3 recordings (with proper SMX-UT filtering if needed- see above).

SM2 or EM3 recordings previously processed with the SonoBat SM2 Batch Compensator utility have compensation encoded into the waveform stored in the file. Processing previously compensated files in SonoBat versions 2.9.7 and 3.1 with SM2 aware enabled would compensate already compensated files and yield spurious results.

SM2 aware button set to off.

Filter and preemphasis settings when SM2 aware is off..

  To use SM2 or EM3 recordings previously processed with the SonoBat SM2 Batch Compensator disable the SM2 aware setting in the SonoBat prerence panel and set the frequency filter to the default value of 5 kHz and the preemphasis setting to medium. Set the filter mode to autofilter if you prefer
     
   
     
 

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