Using an Infrasound Monitoring System With LabVIEW NXG to Understand How Elephants Communicate

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"Thanks to LabVIEW and CompactDAQ, we could quickly create a system to record infrasonic noises from the ZSL elephants and display the data to zoo visitors in an engaging way to promote science and wildlife conservation….Maybe, with the help of machine learning, one day we can improve the welfare of elephants in captivity."

- David Catto, Austin Consultants Ltd

The Challenge:
As part of its new Centre for Elephant Care, the Zoological Society of London (ZSL) wanted to integrate technologies to visualise the infrasonic communications between the herd as an outreach exhibition to promote elephant conservation.

The Solution:
Austin Consultants used LabVIEW and CompactDAQ to develop a unique infrasonic monitoring system with precise acquisition, signal processing, and web-based visualisation. Now on display at the zoo, the system engages and educates the public on how elephants communicate. We also created a version in the new LabVIEW NXG software due to its simple-to-use integrated web tools that make updating and maintaining the system faster.

Author(s):
David Catto - Austin Consultants Ltd
Natalie Latham - Zoological Society of London, Interpretation Developer

Zoological Society of London

Founded in 1826, the Zoological Society of London (ZSL) is an international scientific, conservation, and educational charity. As part of the unveiling of a new £2m Centre for Elephant Care at the zoo’s Whipsnade site, ZSL wanted to further enhance public understanding of these magnificent creatures and promote the conservation of the endangered Asian elephant through a demonstration that visualises how elephants communicate. Some elephant communication is through grunts and grumbles that fall below the human hearing range. Many of these noises take place within the infrasound spectrum that elephants, with their sensitive hearing range, can pick up but people cannot.

 

Austin Consultants

Austin Consultants is an NI Alliance Partner. The company delivers innovative and flexible client-focused engineering design, development, integration, and test solutions to ensure clients fulfill their business and technical goals. From strategy, software development, hardware design, build and integration, to data analytics and machine learning, the company’s smart end-to-end services provide bespoke support at each stage of the product life cycle.


Figure 1. Asian Elephants at ZSL Whipsnade Zoo

 

Walk With the Elephants, Talk With the Elephants

Austin Consultants and ZSL agreed to use a sensitive microphone capable of capturing sound down to 1–2 Hz to capture the noises being made by the elephants. We could then translate live data onto a projected display alongside the viewing platform in the centre, which visualises and explains live elephant communications to visitors. The system would also play back pre-recorded communications to ensure that all zoo visitors could experience and understand how the elephants communicate, even when the elephants were out of microphone range.

We also needed to meet a tight deadline for project delivery because of a royal visit to officially unveil the elephants’ new home by Her Majesty, Queen Elizabeth, accompanied by His Royal Highness, The Duke of Edinburgh.

 

Data Acquisition and Signal Processing

Noise performance and sensitivity were critical aspects of this project, so our team selected LabVIEW and the NI-9250 input module in a CompactDAQ chassis to manage signal processing and data acquisition with prebuilt functions.

We used the NI-9250 to measure signals from the integrated electronic piezoelectric (IEPE) microphones to deliver a wide 
dynamic range, incorporating software-selectable AC/DC coupling and IEPE signal conditioning. When used with NI software, this module provides processing functionality for condition monitoring, including frequency analysis. The PCB Piezotronics IEPE  microphone we chose had a working range that dropped below 20 nHz, but also had a flat frequency response over this infrasound range, making analysis slightly easier in the short timescales. The features of the NI-9250 combined with the ease and speed of configuring LabVIEW to the project requirements made both products a natural choice.

We mounted the CompactDAQ system and microphone within the elephant centre, keeping acquisition close to source to reduce 
additional electrical noise. We acquired the signals at a sample rate of 25 kHz, fully utilising the anti-aliasing filtering and differential inputs of the NI-9250. We processed and logged the data using code written with LabVIEW on an industrial Windows PC positioned in a plant room within the elephant centre close to the viewing platform and display.

 

Web-Based Data Display and Migrating to LabVIEW NXG

We originally encoded the generated data in JSON and passed it to an attractive web-based front-end display (made with HTML and JavaScript) through a web socket connection. We wanted to make sure the visitors could see that the data was live, so we simultaneously detected and displayed both the infrasonic sounds and the sounds that fall within human audible range.

During development, NI released LabVIEW NXG and the LabVIEW NXG Web Module, which includes tools to create a web-based display from within the software itself. Our original system used many external tools to get the data from LabVIEW to the web, so we decided to migrate the system to LabVIEW NXG. This means we can now use a single environment to capture data, code the application, configure the web server, and design and host the webpage using a WebVI, which is extremely powerful. We could include cutting-edge JavaScript components right inside the WebVI to give the customer the wow factor they wanted. Keeping everything in one tool makes future upgrades and system maintenance simpler and faster.

The migration itself was a relatively simple process, as we used the built-in migration tool in LabVIEW NXG. We could simply supply the location of our existing project to create a new LabVIEW NXG version. The system generated a conversion report to tell us what did and did not migrate correctly, so we could quickly make minor changes to the code and fix the issue.

Austin Consultants user experience and web design specialists worked with ZSL to understand the requirements for the display 
interface to ensure it fulfilled not only the educational and informational requirements, but also the accessibility and cognitive needs of the wide range of zoo visitors.

After reviewing many interface options, we identified a real-time frequency spectrum with ~10 seconds of history as the most effective and interesting. The public can hear audible noises, then turn and look at the display to identify any inaudible sounds that may have been made at the same time. The final display runs within a full-screen chromium browser and harnesses advanced web technology, including 3D WebGL rendering and visualisation engines.


Figure 2. Simultaneous Visualisation of Audible and Infrasonic Elephant Communications

 

Engage and Inform

We faced several challenges in designing this system. We were working in a niche area of the audio spectrum and distilling complex information into a user friendly, exciting, and inspiring display. Many people have commented on how interesting it is to just stand and watch the display!

The infrasound region is full of other noises such as the movement of buildings, low-end engine noise, and air conditioning systems. Our processing helps remove some of these distracting noises, but deliberately not all of them, to give the public reference even when the elephants are feeling a little shy.


Figure 3. Marching Elephants at Whipsnade Zoo

 

The new approach with LabVIEW helped ZSL harness technology to deliver new insights and promote scientific understanding of the elephants and their behaviour. As part of the royal visit to officially unveil the centre, the Duke of Edinburgh was very interested to learn about the technology used.

 

Applying Machine Learning to Interpret the Elephant Noises

To further understand the elephant noises, the Austin Consultants machine learning team are currently working to develop an algorithm that can identify certain types of calls, patterns, and maybe even specific individual elephants. The longer-term ambition of this exciting project is to attempt to interpret these calls, for example, by associating them with activities and behaviours. This could even help us determine when an elephant is ill, but not displaying any visible symptoms.

This also has wide applications for industry. For example, we can apply machine learning algorithms to condition monitoring and predictive maintenance of industrial equipment. By analysing typical models of operation, we can use changes that fall outside normal parameters to provide an early indication of a potential fault; thus, highlighting a maintenance requirement before the equipment fails, reducing down time, and cutting costs.

 

Conclusion

Thanks to LabVIEW and CompactDAQ, we could quickly create a system to record infrasonic noises from the ZSL elephants and display the data to zoo visitors in an engaging way to promote science and wildlife conservation. With the new tools in LabVIEW NXG, we could quickly move all data acquisition, analysis, and control within the LabVIEW environment. We are now finalising the migrated system and hope to deploy in the near future. Maybe, with the help of machine learning, one day we can improve the welfare of elephants in captivity.

 

Author Information:
David Catto
Austin Consultants Ltd
Tel: 0800 772 0795
marketing@austinconsultants.co.uk

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