Research Projects
Melting glaciers
Several years ago, well known Scottish artist Katie Paterson came to us looking for help on a new project. She wanted to listen to the sound of a melting glacier and let people experience these sounds in real time. We built a custom DolphinEar wireless system to make that project a reality and people from over 130 countries dialed into it from their home and mobile phones to hear the sounds of a melting glacier with their own ears.
What they heard (listen yourself) was the sound of the popping of ancient air bubbles compressed and frozen into the ice thousands (or hundreds of thousands) of years ago. As the ice melts, the compressed air is released suddenly as a ‘pop’. That’s what you are hearing.
But those bubbles also tell another story. By listening to the number and pitch of those bubbles we can estimate the rate of melting. What was surprising is that we saw very little difference between the popping rate when we compared recordings made during the summer and winter periods. We would have expected the melt rate to be very much lower in the cold winter months. But it wasn’t.
This project also proved you could use weak mobile telephone signals in remote areas of the world to provide useful climate and monitoring data. Access from anywhere in the world is as simple as dialing a telephone number!
Dolphins have names
Every dolphin has its own unique ‘signature whistle‘. Listening to these whistles is one way to identify specific dolphins and track their whereabouts.
Bottlenose dolphins ( Tursiops truncatus ) have elaborate sound production and receiving systems.
In the Tursiops, four major types of vocalisations have been identified: whistles, clicks, burst pulsed sounds and chirps.
Whistles are used in communication. They are continous, narrow-band, frequency-modulated pure tones, limited in frequency to the mid- and upper- range of the sonic spectrum, generally from 0.2 to 24 kHz, and of 0.5s in duration. Most of their energy is below 20 kHz.
Clicks are directional and used for echolocation. These are short, broad-band pulses ranging from .2 to 150 kHz. Pulse duration is 50 to 80ms. The interclick interval ranges from 10ms to ~160ms. Dolphins are able to click and whistle at the same time.
Burst pulsed sounds occur commonly in social and emotional context and are thought to be used for communication. These are trains of clicks with repetition rates of up to 5000 clicks per second. The high repetition rate gives a tonal quality to the sounds.
Chirps are thought to be used in communication. These sounds are pulsed, frequency-modulated, broad-band sounds. Frequency modulation occurs in different frequency bands
All of the communications related sounds are well within the human hearing range. Even the echolocation clicks can have audible components within the nominal 20kHz upper limit of human hearing – some go down to 0.2 kHz as stated above.
A DolphinEar hydrophone and the software included in the package can get you started in your own research.
Trees transporting water
A modified DolphinEar 200 Series hydrophone was used to record the sounds made by a horse chestnut tree transporting water through its root system and up the tree trunk to the leaves. The recording was used by Roosmarijn Pallandt who incorporated these heartbeat-like sounds into a piece of music which was played to delegates at the United Nations COP26 Climate Conference in Glasgow.
Shisha pipes and Climate research
A researcher in the Middle East came to us to ask if DolphinEar hydrophones could detect bubbles within a shisha pipe – one of those water pipes where tobacco is filtered through a reservoir of water before it reaches the user’s mouth.
He wanted to calculate the volume of smoke and any harmful or addictive substances that reached the user. This was done by mounting the DolphinEar hydrophone disk under the base of the shisha pipe. Using the spectrogram software that comes with every DolphinEar hydrophone he was able to calculate the size of the bubbles based on their pitch using Minnaert resonance. (see https://en.wikipedia.org/wiki/Minnaert_resonance and follow the links to research papers. See also: https://pubs.aip.org/asa/jasa/article/131/1/EL61/824297/Laboratory-investigation-of-a-passive-acoustic )
A similar technique can be used to calculate the release of greenhouses in various situations. (see below)
Methane in the cryosphere
Bubbles hold many secrets, for example, how much greenhouse gas is being released from frozen methane hydrates that lie on the sea bottom, or in Arctic ponds as plant matter decays with increasing global temperature.
Flow rates from these seeps are of interest for their potential contribution to atmospheric methane levels.
Just as with the bubbles in the shisha pipe example above, a DolphinEar hydrophone with spectrogram software can be used to record the release of methane bubbles and calculate the rate of gas emissions using Minnaert resonance.
(see https://en.wikipedia.org/wiki/Minnaert_resonance and follow the links to research papers.
See also: https://pubs.aip.org/asa/jasa/article/131/1/EL61/824297/Laboratory-investigation-of-a-passive-acoustic ) .
Bubbling methane pockets
Methane (CH4) is released as organic matter decays in an oxygen free environment. It is why landfill sites now have methane recovery systems to capture the gases from the enormous amounts of organic waste we dump every day. This process occurs everywhere. Here is a recording from a DolphinEar user who noticed bubbles seeping up from the sand.
“I was recording this morning at Hauxley, Northumberland (warm and sunny, nice whimbrel, knot and roseate terns – shame about the F-15s) when I noticed that the beach around me was making a significant contribution to the soundscape.
“At first I thought that the bubbling noise was coming from lugworm burrows, but then I realised that I’d never heard lugworm burrows make a noise, and that the sound was coming from just a small area of beach.
“Closer inspection revealed that the sand had covered a mass of fermenting kelp, that was producing a constant stream of foul-smelling gas bubbles through the sand.
“So I dug a hole for my DolphinEar Pro hydrophone, and this is the result: Fermenting seaweed.”
We think it’s one of the most alarming and important recordings we have heard in years. The activity you can hear from just a few kilos of seaweed decomposition is astounding.
Underwater robotic research
McGill University- Aquatic Walking Robot :
“The listening apparatus consists of four DolphinEar/PRO omni directional hydrophones, which are attached at the corners of a square buoy of size 1.0 x 1.0m, shown above. Sampling frequency was 44100 Hz, signal resolution 16 bits, sample size 2048 samples.”
JASA: Aquatic noise stress in fish
Effects of varying levels of noise and vibration on behavioral and physiological stress responses in two species of freshwater aquarium fish
Alexandra Rose; Jeanette Thomas; Allen LaPointe
Scientific Papers
DolphinEar™ hydrophones have along history of use in the scientific community. Here is a small sampling of published papers showing the diversity of projects where they have been used …
A method to reduce the multi-path propagation effect in hydroacoustic characterization.
GM Constantin, M Paun, A Danisor… – OCEANS 2023 …, 2023 – ieeexplore.ieee.org
… The possibility of determining the characteristics of a DolphinEar ProTM hydrophone was … To measure the frequency characteristic of the DolphinEar Pro™ acoustic transducer, a two…
Submerged calling by oregon spotted frogs (Rana pretiosa) Remote from breeding aggregations
J Bowerman – Reptiles & Amphibians, 2010 – journals.ku.edu
… sub-surface listening was conducted using a DolphinEar™ hydrophone (model DE100-6-112), with a 6-m cable and preamp or DolphinEar™ PRO hydrophone connected directly to a …
Sensing River and floodplain biodiversity–developing a prototype
U Wissen Hayek, F Gutscher… – Journal of Digital …, 2023 – research-collection.ethz.ch
… DolphinEar Pro™ hydrophones (https://dolphinearglobal.com). The VR mic was mounted on top of a monopod. The hydrophones were attached to each end of a 20 cm long rod and hung …
Effects of varying levels of noise and vibration on behavioral and physiological stress responses in two species of freshwater aquarium fish: Fathead minnows …
A Rose, J Thomas, A LaPointe – The Journal of the Acoustical Society …, 2008 – pubs.aip.org
… of several fish galleries at the Shedd Aquarium using a BK 2560 SPL meter; Leq, SEL, and minimum & maximum decibel levels were measured up to 2 kHz using a DolphinEar …
Field observations of iceberg deterioration
B Veitch, M Williams, A Gardner, B Liang – PERD/CHC Report, 2001 – researchgate.net
… hydrophone, the DolphinEAR™. The frequency response is a few Hz to more than 22kHz, and the sensor is packaged with power supply and cable. Two DolphinEAR units were procured, …
Spectral analysis of ultrasound rf image data to monitor cavitation and thermal bubble formation in HIFU treatment
C Hsieh, PP Smith, G Ye – 2008 IEEE Ultrasonics Symposium, 2008 – ieeexplore.ieee.org
… RESULTS The response of the DolphinEar™ hydrophone was investigated first to monitor the thermal emission of bubbles. Figure 5(a) shows the response after HIFU heating. Spectral …
The Influence of Boating Noise on the Parental Care Behaviors of Smallmouth Bass (Micropterus dolomieu)
A West – 2025 – rave.ohiolink.edu
… collected through video recording via an underwater drone (QYSEA FIFISH V6) and all sound measurements were recorded via an omnidirectional hydrophone model: DolphinEar™ …
Proposed framework for multi-level extreme machine learning for underwater thruster’s fault classification using YIN fundamental frequency estimator and pitch sound
TK Chan, CS Chin – 2017 2nd International Conference on …, 2017 – ieeexplore.ieee.org
… The hydrophone utilized in this project is the hydrophone from the DE200 kit from DolphinEar which comes with an 8-metre cable length, headphone amplifier, …
Positioning of autonomous underwater vehicles using machine learning techniques
EV Carrera, C Soria – 2023 IEEE Seventh Ecuador Technical …, 2023 – ieeexplore.ieee.org
… The testbed configured for the positioning of an underwater vehicle consists of a pool of irregular dimensions, where four DolphinEar DE200™ hydrophones are arranged in two …
Health stages diagnostics of underwater thruster using sound features with imbalanced dataset
TK Chan, CS Chin – Neural Computing and Applications, 2019 – Springer
… A low-cost hydrophone and DE200 from DolphinEar comprises of 8-meter cable length with a headphone amplifier. The amplifier was then connected to a handheld voice recorder, …
Underwater acoustic noise characteristics of shallow water in tropical seas
AZ Sha’ameri, YY Al-Aboosi… – … on Computer and …, 2014 – ieeexplore.ieee.org
… The signals were received through a broadband hydrophone (7 Hz a 22 kHz) model DolphinEAR™ 100 Series, located about 5000 meters from the shore and at different depths from 1 to …
Diurnal variability of underwater acoustic noise characteristics in shallow water
YY Al-Aboosi, A Kanaa, AZ Sha’ameri… – TELKOMNIKA …, 2017 – telkomnika.uad.ac.id
… The segments were received through a broadband hydrophone (7 Hz ~ 22 kHz) model DolphinEAR™ 100 Series, at different depths from 1 to 5 meters with sea floor at a depth of 10 …
Passive positioning of autonomous underwater vehicles
EV Carrera, D Guevara – International Conference on Applied …, 2022 – Springer
… The scenario also includes four DolphinEar DE200™ hydrophones connected to a Behringer U-phoria UMC404HD audio interface with a cumulative sampling rate of 192 kHz and 24-bit …
Male calling activity in syntopic populations of Rana latastei and Rana dalmatina (Amphibia: Anura)
R Sacchi, R Cigognini, A Gazzola, F Bernini… – Italian Journal of …, 2015 – Taylor & Francis
… We used a continuum recording system consisting of an omnidirectional underwater hydrophone (DolphinEAR™ piezo transducer, frequency response 7–22000 Hz) connected …
W STATION ‘BOMB-OGENESIS’
search.ebscohost.com
… With the aide of sponsors Virgin Mobile and Dolphinear™, she placed a hydrophone into the lagoon where the glacier is disappearing and callers were able to hear the sounds of water …
First description of the acoustic repertoire of Rana italica (Anura, Ranidae)
E Razzetti, R Sacchi, JE Platz – The Herpetological Journal, 2006 – ingentaconnect.com
… Recordings were obtained using a omnidirectional MPC piezo hydrophone (Dolphinear, frequency range 7 – 22,000 Hz) and a Sony TC-D5 cassette recorder. All records were …
Wake-like skin patterning and neural activity during octopus sleep
A Pophale, K Shimizu, T Mano, TL Iglesias, K Martin… – Nature, 2023 – nature.com
… Stimulus strength was calibrated using a hydrophone (DolphinEar DE200™), placed in the position of the octopus. Three strengths of stimulus 6, 40 and 86 dbV were delivered to the …
Acoustic conditioning for recall/recapture of escaped Atlantic salmon and rainbow trout
MF Tlusty, J Andrew, K Baldwin, TM Bradley – Aquaculture, 2008 – Elsevier
… Once calibrated, the system was validated routinely in the experimental tanks with a DolphinEar 100 series hydrophone (www.dolphinearglobal.com). The system allowed for sound intensity …
DETERMINING THE EFFECTS OF PATERNITY ON LOCOMOTIVE PERFORMANCE AND MORPHOLOGICAL VARIATION IN LOGGERHEAD HATCHLINGS
AR Hennessey – 2025 – hammer.purdue.edu
… To enhance detection, staff also utilized surface microphones (DolphinEar Pro™) to listen for in situ sounds associated with hatchling activity, such as digging, chirping, or movement …
Cruise Report
WR Nelson, RS Appeldoorn – R/V Seward Johnson: a submersible …, 1985 – bodc.ac.uk
… Description of acoustic equipment: The acoustic study on this cruise was carried out using a DolphinEAR™ 7Hz-22000Hz omnidirectional hydrophone. At each station (except station 6 ) …
Underwater Music: Tuning Composition to the Sounds of Science
S Helmreich – The Routledge Companion to Biology in Art and …, 2016 – taylorfrancis.com
… Heated’s liner notes report the use of the following: “2 × 8011 DPA hydrophones, 2 × DolphinEAR/PRO™ hydrophones and 2 × 4060 DPA microphones.” Winderen is artist and empirical …
New water and air pollution sensors added to the Sonic Kayak citizen science system for low cost environmental mapping
AGF Griffiths, JK Garrett, JP Duffy, K Matthews, FG Visi… – BioRxiv, 2020 – biorxiv.org
… Much of this cost is taken up by a hydrophone costing ~£300 (DolphinEar pro™), and the waterproof bluetooth speaker costing ~ £140 (Ultimate Ears Megaboom 3), each of which may …
Experimental multipath delay profile of underwater acoustic communication channel in shallow water
YY Al_Aboosi, AZ Sha’ameri – Indonesian Journal of Electrical …, 2016 – researchgate.net
… The signal was received using a broadband hydrophone (7 Hz–22 kHz) model DolphinEAR™100 Series). The maximum cable length was 30 m Figure 4. The wind speed was about 7 …
Course of an Isolated Ranavirus Outbreak in a Pelobates fuscus Population in The Netherlands
A Spitzen-van der Sluijs, F Pasmans… – Journal of …, 2016 – meridian.allenpress.com
… The common spadefoot toad is difficult to detect because both sexes call for mates under water; hence, a hydrophone (DolphinEar DE200™) was used from 2010 onward to detect their …
The Northern Red-legged frog (Rana aurora) at the Millard Learning Center
E Higgs, J Duncan, T Overeem, M Catanzaro, M Lewis – 2018 – galianoconservancy.ca
… aurora, the surveyor must place a hydrophone (Dolphinear™) into the water …
[BOOK] Wild soundscapes: discovering the voice of the natural world
by Bernie Krause (Author), Roger Payne (Foreword) – 2016 – books.google.com
Through his organization Wild Sanctuary, Bernie Krause has traveled the globe to hear and record the sounds of diverse natural habitats. Wild Soundscapes, first published in 2002, …
Aqua: An amphibious autonomous robot
G Dudek, P Giguere, C Prahacs, S Saunderson… – Computer, 2007 – ieeexplore.ieee.org
… The listening apparatus consists of four DolphinEar/PRO™ omnidirectional hydrophones, which are attached at the corners of a 1 m 1 m square buoy, shown in Figure 5. …
[PDF] z Mammalia aequatorialis ? O TS
JP Oña, A Eguiguren, P Moscoso – researchgate.net
… to humpback whale songs in real-time, tourists were given semi-professional headphones (Sony ZXl 10) connected to a Tascam DR-40 digital recorder and an H2aXLR or DolphinEar™/…
Whale Song is a Language Precursor with Context Free Grammar
K Otsuka – 2025 – researchsquare.com
Previously, no evidence existed for the early stages of language evolution. Here, the recursive ordering rules of hump back whale song—encoded in the mutually exclusive periodic … Data were collected off Ma’alaea Bay, Maui Island. The recordings of song were made using a system that connected 8 m, 12 m, and 24 m DolphinEar DE200 hydrophones™ to ZOOM R20 multitrack PCM recorder via XLR terminals, with a sampling rate of 44,100 Hz and 24-bit resolution.
Complex Sound Discrimination in Zebrafish: Auditory Learning Within a Novel “Go/Go” Decision-Making Paradigm
A Patel, S Mattapalli, JS Kanwal – Animals, 2025 – mdpi.com
Previous anatomic and physiologic studies of the peripheral and central auditory system, with rare exceptions, have relied on the use of tonal stimuli. Figure 2C,D show the spectrograms of both sounds as recorded with a hydrophone (DE-PRO™, DolphinEar Global™) with an omnidirectional configuration and a wide frequency-response of 1 Hz to 24 kHz.
Sound enhances wastewater degradation and improves anaerobic digester performance
John H. Loughrin1 · Nanh Lovanh1 · Stacy W. Antle1 · Michael D. Bryant1 · Zachary P. Berry2
Biogas production and wastewater quality from anaerobic digesters were studied to determine whether sound at sonic frequencies (< 20,000 Hz) could enhance their performance. Recording was performed using a DolphinEar DE200™ hydrophone (www.dolphinearglobal.com) interfaced to a computer using Audacity recording software
A Compact Monopole Antenna for Underwater Acoustic Monitoring Beacons
By Alin Danisor https://doi.org/10.3390/S22218392
Protected wetlands such as deltas, lakes or rivers provide a sanctuary for many endangered species. In order to protect these areas from illegal human interventions, it is necessary to monitor the unauthorized entrance of motor boats. In order to mitigate such an impact, we have developed a network of floating beacons for underwater acoustic monitoring, using LoRa communication modules operating at 433 MHz. The sound transducer is a DolphinEar PRO-10™ wideband (1–24 kHz) omnidirectional hydrophone.
Sound enhances wastewater degradation and improves anaerobic digester performance
2019. John Loughrin, Wastewater, Anaerobic Exercise. SN Applied Sciences
Hydrophone model DolphinEAR DE200 series. Biogas production and wastewater quality from anaerobic digesters were studied to determine whether sound at sonic frequencies (< 20,000 Hz) could enhance their performance. Anaerobic digesters exposed to sound produced approximately 12% more biogas than did non-exposed digesters, and sound-treated digestate had significantly lower chemical oxygen demand. Sludge at the end of the 100-day digestion averaged 19% less carbon and 18% less nitrogen in sound-treated digesters as compared to sludge from untreated digesters. UWAN is registered by the hydrophone model (Dolphin-EAR DE200 series), that they convert into a discrete time representation for more treating and store in a computer at type (PC).
Statistical properties of underwater acoustic noise in Lake Hamrin, Diyala, Iraq
Thamer Easa Murad, Yasin Yousif Al-Aboosi
Department of Electrical Engineering, Collage of Engineering, Al Mustansiriyah Universit, Baghdad, Iraq
The greatest challenge in underwater acoustic communication systems is the minimization of underwater impact noise. This article offers an empirical example for determining the statistical properties of underwater acoustic noise in the in Lake Hamrin. Hydrophone model DolphinEAR DE200 series
Song recordings suggest feeding ground sharing in Southern Hemisphere humpback whales
Elena Schall1*, Divna Djokic, et al.
The Atlantic sector of the Southern Ocean (ASSO) has one of the highest densities of Antarctic krill (Euphausia superba) compared to other polar and subpolar regions, which attracts migratory baleen whale species to aggregate in this area for feeding. DolphinEar/PRO™ hydrophones used in Ecuador recordings.
Male calling activity in syntopic populations of Rana latastei and Rana dalmatina(Amphibia: Anura)
2014 Edoardo Razzetti, Italian Journal of Zoology
These are two amphibian species protected by the European Union. The two species have very have different repertoires of vocalisations. Recordings were made using a DolphinEAR™ piezo hydrophone, frequency response 7–22000 Hz)connected by a 20-m shielded wire to a PC that recorded sounds non-stop within the pond.
Convergence and divergence of songs suggests ongoing, but annually variable, mixing of humpback whale populations throughout the North Pacific
2019 Manami Yamaguchi
The purpose of this study was to describe the relationship of humpback whale populations across the North Pacific based on song composition. Recording equipment varied between locations, but all were professional quality digital recorders and hydrophones as follows: Philippines, Zoom H4N recorder with DolphinEAR Pro™ hydrophone …
Bahan Ajar-1 Teknik Audio Engineering
M Bimo Cahyo Pratomo
The DolphinEAR™ Hydrophone mic can be planted underwater to a depth of 100 meters for long periods of time to monitor underwater sounds (whales, dolphins, submarines, human voices from ships, etc.)
America’s Loch Ness Monster: Champ
2019 Katy Elizabeth
“On July 2014 at approximately 7:45 PM in an area of Lake Champlain called Scotch Bonnet with our Dolphinear™ Hydrophone system, we captured a pulsating sound, a lower frequency of Echolocation.”
Soundhunting in a City: Chronicles of an Urban Field Recording Expedition
2012 Budhaditya Chattopadhya
… is an art practitioner, primarily engaged with the audio media. He incorporates field recording, visual image and spatial practice generating a diverse range of sound-based artworks for installation and performance. He is also involved with practice-based research in perception and cognition of sound. The equipment used included … a DolphinEar™ Professional Hydrophone.
Evaluation of Neural Networks for Data Classification, Recognition, and Navigation in the Marine Environment 2004 Brian Howel
Sound sources in this category include propeller noise, hull transmitted engine noise, fin swishing of a diver, and various pump and motor sounds. For military and harbor security applications, these are the sounds of the utmost interest. DolphinEar™ hydrophone was used for Boat, Humpback Whale, Dolphin sound detection and recording
The Water Beetles of Pollardstown Fen
Dr. Tom Lawrence (1966–2011)
Dr. Lawrence was a composer, radio artist and acoustic ecologist. He lectured at Dublin City University. He is published by Gruenrekorder, Touch Music [mcps] and EarthEar. Many of his recordings were made with a DolphinEar PRO™ hydrophone.
Sample listings from Google Scholar and Academia.org. Many more can be found from other sources on the net.
Includes Spectogram software
Every DolphinEar hydrophone comes with a free copy of spectrogram software for Windows PCs.
Hydrophone with 8 metre (26 foot) cable, headphone amplifier, earphones, manual and...
Hydrophone with 16 metre (52 foot) cable, headset amplifier, earphones, manual and...
Hydrophone with 24 metre (78 foot) cable, headphone amplifier, earphones, manual and...
Hydrophone with 32 metre (105 foot) cable, headphone amplifier, earphones, manual and...
Hydrophone with 48 metre (157 foot) cable, headset amplifier, earphones, manual and...