Tag Archives: hydrophones

Hydrophones

A hydrophone is a underwater microphone designed to be used to record or listen to aquatic soundscapes. During River Listening we are testing various hydrophones and experimenting with different recording methods. This post introduces the hydrophones we are using during the River Listening Labs and community workshops.

H2a-XLR Hydrophone

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The H2a-XLR Hydrophone is made by Aquarian Audio Products, a company that designs and builds quality hydrophones for eco-tourism, research and recording professionals. These hydrophones have been used in a variety of applications worldwide, including research, industry, medical and military, and they offer an exceptional cost-performance ratio for those involved in auditory applications. Their designs prioritize high sensitivity, low noise, compatibility with standard audio components, and durability. Aquarian hydrophones produce a great sound at a very affordable price and are our preferred hydrophones for the River Listening community workshops.

JrF D-series hydrophones

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We love the D-series hydrophones handmade by Jez riley French in the UK.  These hydrophones sound great and are very light weight for travelling.  JrF also makes basic hydrophones, but the D-series have are low noise with a flexible specially designed cable and weighted to submerge to any depth needed.
More information here

Aquaear CR-80-40

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The Aquaear CR-80-40 is an encapsulated active ceramic hydrophone designed mainly for research purposes. High quality ceramic with sound-transparent rubber encapsulant provides excellent sensitivity and wide band (up to 80kHz). This hydrophone is ultra-low noise and is great for recording dolphins and fish.
This hydrophone is made by Burns Electronics  in New South Wales, Australia.

Cetacean Research Technology

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We also love the hydrophones made by Cetacean Research Technology in Seattle, USA. They specialize in providing hydrophones and underwater acoustic instrumentation tailored for the applications of scientists, engineers and recording artists.

Since 1994, CRT’s owner, Joseph Olson, has worked with other scientists and engineers to create these devices. As a physicist, Olson has worked with technical instrumentation and underwater acoustics for over 25 years. These hydrophones are used by individuals in over 65 countries ranging from Scripps Institution of Oceanography to National Geographic Television.

Community Field Kits

Our stereo community field kit consists of two Aquarian Hydrophones with a ZOOM H4n. The H4n features built-in XLR connectors with phantom voltage source capability and digitally controlled, high-quality preamplifiers.

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Quadraphonic Kayak Kit

The River Listening quadraphonic kayak kit consists of four Aquarian Hydrophones connected to a ZOOM H6 recorder which features built-in XLR connectors with phantom power and high-quality preamplifiers.

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Advanced Recording Kit

When using the more advanced hydrophones made by Cetacean Research Technology and  Burns Electronics we prefer to use
higher quality preamplifiers. The products we find to produce the best sound quality are made by Sound Devices. We particularly like the MixPre-D,  which features two studio-grade mic/line inputs with available limiters, high-pass filters and phantom power. The “D” in MixPre-D indicates the infusion of extensive digital technology. In addition to 24-bit AES digital outputs, USB audio streaming is provided for Mac OS, Windows or Linux computers. When the MixPre-D is connected to a computer with a USB cable, the operating system recognizes it as a USB Audio Class compliant device. This means we can connect the MixPre-D to a digital recorder, a laptop, or even an iPad during the River Listening Labs.

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We also love the Sound Devices 722, a favourite among many field recordists and sound artists. This is undeniably one of the best products available for field recording. The 722 is a portable, high-resolution audio recorder with internal hard drive and is a very durable device. It has similar high-quality low-noise microphone preamplifiers to the MixPre-D, with the added flexibility to record to its internal hard drive and removable memory cards.

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Why listen to rivers?

In our current state of environmental crisis, biodiversity assessment is critical to understanding the rapid ecological changes taking place across the globe. In the last ten years, there has been a strong emergence of non-invasive monitoring involving auditory recordings of the environment. This emerging field is commonly referred to as soundscape ecology and shares many parallels with other fields, including bioacoustics. Soundscape ecology has an array of creative possibilities that have been deeply explored by practitioners including Bernie Krause. The literature suggests it will continue expanding within scientific fields, with a particular focus on the importance of soundscape conservation, the impact of noise pollution, and the value of soundscapes to assist with biodiversityanalysis. There are now a growing number of international projects and scientific institutions embracing methods of bioacoustics in biodiversity analysis of aquatic environments.

River Listening is a practice-led interdisciplinary collaboration of freshwater biodiversity, virtual technologies, soundscape ecology and environmental sound art to explore methods of hydrophonic recording, soundscape analysis and virtual dissemination. Despite the rapidly growing interest in emerging auditory fields such as bioacoustics, there is yet to be standardised approaches to field recording and interpreting the data. While scientists have developed advanced software tools for species recognition, there is a growing need to consolidate the available tools and explore the value of listening to the data in new ways. There are also exciting possibilities to make this data available for a wider audience through digital technology and creative collaborations.

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Leah Barclay recording on the Noosa River

The River Listening Synapse residency specifically involves field labs on the identified rivers experimenting with various hydrophonic recording techniques and sound processing. The labs each involve a three-week immersive engagement process, which is based on a methodology developed during my doctoral research. The labs involve three daily recording sessions; sunrise, midday and dusk. Each recording session is approximately two hours, with a custom-made quadrophonic hydrophone rig attached to a moving kayak. These recordings are databased onsite, and made available online for analysis at the Australian Rivers Institute.

In addition to the kayak recordings, other field kits are distributed on location to capture sounds without human intervention. These include a stationary hydrophone that records from the same location during the entire field lab and a series of smaller field kits to capture the soundscapes above the water. The additional field kits are useful to analyse particular sound sources in the hydrophone recordings that might be difficult to identify. The recording sessions are accompanied by community workshops and creative development experiments involving streaming and processing the hydrophone recordings. The team will facilitate a range of community events and will also collaborate with existing programs in each river community.

The field labs are designed in an open format and encourage collaborations with the local community. The future outcomes will be made available through a virtual sound map and public listening sessions in Queensland, Australia. The database of recordings will form the foundation for a series of experiments at the Australian Rivers Institute to explore new methods in understanding and analysing the data from a scientific and creative perspective.

I’m thrilled to have the opportunity to collaborate with The Australian Rivers Institute (ARI) on River Listening. The Australian Rivers Institute is Australia’s largest university aquatic ecosystem research group with globally recognised expertise in river, catchment and coastal ecosystems. ARI is currently leading a range of innovative projects revolving around catchment and river ecosystem processes, aquatic biodiversity and conservation, and aquatic ecosystem monitoring and assessment. 

While I’m working with several researchers at ARI, the scientific grounding of the River Listening collaboration is directed by ARI Senior Research Fellow Dr Simon Linke, one of Australia’s leading freshwater conservation scientists, whose pioneering work in biomonitoring and river conservation planning has been used by agencies and NGOs from South East Queensland to the Congo. Simon has a strong interest in bioacoustics and was introduced to me Dr Toby Gifford, a music technologist from the Queensland Conservatorium of Music. Dr Gifford is a world-leader in real-time audio processing, machine listening and automated musical scene description who has worked with the ARI to explore future frameworks for a real-time bioacoustic wildlife population monitoring network for Australian waterways. We hope some of the results from River Listening can be incorporated into the broader aquatic bioacoustics visions of ARI in the future.  

As the international interest in the emerging auditory fields of bioacoustics and acoustic ecology continues to expand, there are clear opportunities to harness virtual technologies to develop accessible community engagement around the creative and scientific possibilities of listening to the environment. River Listening provides a model to develop a truly interdisciplinary approach at the critical stage of creative development and it is anticipated the future results will be beneficial to national ecosystem monitoring programs. I also hope that River Listening could become a catalyst for community engagement and interdisciplinary thinking at a time when the conservation and management of aquatic ecosystems is a critical priority. At the conclusion of the River Listening labs in Queensland, the research team hope to expand this project across Australia and  beyond.

Mary River, Queensland
Mary River, Queensland