Life and The Way to Knowing: So You Want To Hunt The Yowie? - Part 4

Software

At some point you will want to analyse some of the samples you have collected. Hair for example can be obtained directly from traps, leaf litter where it has been naturally shed or even from scat. Audio recordings may be noisy and unclear. They would thus benefit from some filtering and post-production amplification or compression through an audio editing program. The following software can assist with both of these undertakings.

Hair Analysis

Hair ID

http://www.ecobyte.com.au/index.html

Hair ID is a software package that has been designed to make the process of hair analysis simpler and more accessible. The software package has two main parts:

A database of information on the hair of 110 Australian mammal species. This database is the first published extension to the original material published in the Brunner and Coman (1974). The information in the database is original material that is not available anywhere else.

A comprehensive reference section that describes the nature of hair, and gives detailed instruction on the techniques of hair analysis. This section is an updated and extended version of the original work in Brunner and Coman (1974) presented in electronic format.

Audio Editing

So you may have recorded some audio but there is so much hiss or background noise that you can't really hear the important sounds unless you have headphones on, stand on one leg and hold your tongue to the left. Honestly that's not really going to cut it.

Some of the problem may be due to the equipment used to record the sound sample (more on that later) but there may be some post-processing that can be done to clean up the sound, reduce the white noise and bring up that elusive sound from where it is hiding in the background.

To do that you will need some audio editing software. There are literally hundreds of programs available in various quality and price ranges. Below are just a few of the ones around, beginning with a free product.

Audacity – Free Multi-track Audio Editor and Recorder

http://sourceforge.net/projects/audacity/

Avisoft Bioacoustics Software – Various levels from Lite to Pro

http://www.avisoft.com/downloads.htm

http://www.avisoft.com/pricelist.htm

Raven – acquisition, visualization, measurement, and analysis of sounds

http://www.birds.cornell.edu/brp/raven/RavenOverview.html

http://www.birds.cornell.edu/brp/raven/RavenPricing.html

iZotope Rx5 Audio Editor

https://www.izotope.com/en/products/audio-repair/rx

iZotope Rx Post Production Suite

https://www.izotope.com/en/products/bundles/rx-post-production-suite/

I have used Audacity a few times for mixing/patching songs and I have seen iZotope RX5 in use but have not checked out the others. A helpful feature of RX5 is its ability to graphically display the frequency of an audio event. This may be used to differentiate between events that may otherwise be indistinguishable due to similar timing between events, such as Yowie stomping and Wallaby hopping.

(https://www.youtube.com/watch?v=negFjmMnlOM 3:34 to 6:20, [YouTube User] TheRusty222).

Whichever product you choose make sure you run through available tutorials that may be available and perhaps seek out an audio-specific forum where you can get good advice for free.

Audio Recording Equipment

Audio – General Considerations

With the advance in technology, high quality digital recorders are everywhere now. Having said that, there are some points you should consider aside from things like microphone type/pattern that you can read about in the resources linked above.

Size

Many audio recorders are portable but that also comes with some quality and endurance compromises. The audio may be compressed to save space and the battery life may mean a shorter run time on site. Do some homework on the specifications before buying.

Sample Rate and Audio Format/Compression

This can be confusing so I apologise in advance. When choosing a recorder you want to get one that can give you access to the data in a format that contains the most information. There are two factors to consider.

How many bits at a given sampling rate is recorded, and

In what format is it recorded?

Sample Rate

Recorders give specifications like 16-bit/44kHz or 24-bit/96kHz, so what is that about? The number of bits refers to an instantaneous sample of information taken from a live audio signal and 24-bits is obviously more information than 16-bits. This parameter is called bit depth and is a limiting factor for dynamic range and signal-to-noise ratio of recordings. The kHz figure is the sample rate or how many times this sample is taken per second and again, 96 kHz is better than 44 kHz and 192 kHz is better again with more information captured. Sample rate can determine the range of frequencies captured.

The latest crop of handheld recorders offer 24-bit/96kHz specifications. To get any better sample rates the devices are bigger and possibly impractical for field use.

Audio Format

So as you capture your data you need to save it into a file format you can edit and play on a computer. The main types of file formats are:

Uncompressed audio files such as WAV
Lossless Compression. File types like FLAC and WMA (lossless), and
Compressed audio files like MP3, AAC and WMA (lossy).

In the latest generation of handheld recorders you generally get a choice of an uncompressed format like WAV as well as a compressed option like MP3. Both should have selectable bit-rate. If you opt for compression try to select a higher bit-rate like 256kbps so less information is lost in the compression process while still saving space. Again it will be a trade-off between data storage and audio file quality.

Audio Recorder Models

These are numerous so pick one with the right features for your budget. Some examples are linked below that have multiple hand held models at different price points, however, there are many other brands available like Sony, B&H, Olympus, etc.

NAGRA - http://www.nagraaudio.com/recorders/

ZOOM – https://www.zoom.co.jp/products/field-video-recording/field-recording

TASCAM – http://tascam.com/applications/recording/handheld_recorder/

Audio Recorder - Field Use considerations

So now that we have surveyed the scene a bit, you may want to start thinking about how you are going to use the recorder in the field. When you do, there are some microphone, size and package considerations.

Attended Use

If you are going to use the microphone while you are there with it, then you may be able to get some use out of a directional or parabolic microphone rig that can concentrate sound from the specific direction in which it is pointed. In this case you may not need to worry so much about protecting the recorder and can just take it along with you.

Unattended Use

If you wish to capture audio (especially nocturnal vocalisations) over an extended period, then you will want to try and protect the recorder from weather and possible tampering damage. Of course this will mean that using direction microphones is out of the question so you will need to rely on the cardioid microphones built into the recorder. You may want to buy a recorder that has stereo microphones to increase the capture angle.

So you will want to put the recorder in some type of container that remains open where the microphones are situated. Do an internet search and there will be all sorts of rigs in use but a simple and easy one would be a bit of PVC pipe open at one end and painted or wrapped in camouflage net. Mount on a tree or at ground level in a suitably protected location.

Microscopes

Last but not least we will need to pick up some equipment for the making bigger of very tiny things.

When analysing hair samples and the components of scat it is beneficial to have a microscope with variable magnification of at least up to x400 or x500 magnification. It also pays to have one with a USB camera option to be able to import sample photographs into software for comparison with known samples.

Below are a couple of likely rigs. Shop around as there are a lot of options available.