The unsolved mystery sounds of the Southern Ocean #ASA187

Quack-like sounds off the coast of New Zealand in the ’80s may have been a conversation.

Acoustical Society of America

 

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Looking from the stern of the ship as it tows the long horizontal array of hydrophones. The tow cable can be seen going through the metal horn at the stern. The hydrophone array is several hundred meters behind the ship and about 200 meters deep.

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Credit: Ross Chapman

MELVILLE, N.Y., Nov. 21, 2024 – Mysterious, repeating sounds from the depths of the ocean can be terrifying to some, but in the 1980s, they presented a unique look at an underwater soundscape.

In July 1982, researchers in New Zealand recorded unidentifiable sounds as a part of an experiment to characterize the soundscape of the South Fiji Basin. The sound consisted of four short bursts resembling a quack, which inspired the name of the sound “Bio-Duck.”

“The sound was so repeatable, we couldn’t believe at first that it was biological,” said researcher Ross Chapman from the University of Victoria. “But in talking to other colleagues in Australia about the data, we discovered that a similar sound was heard quite often in other regions around New Zealand and Australia.”

They came to a consensus that the sounds had to be biological.

Chapman will present his work analyzing the mystery sounds Thursday, Nov. 21, at 10:05 a.m. ET as part of the virtual 187th Meeting of the Acoustical Society of America, running Nov. 18-22, 2024.

“I became involved in the analysis of the data from the experiment in 1986,” Chapman said. “We discovered that the data contained a gold mine of new information about many kinds of sound in the ocean, including sounds from marine mammals.”

“You have to understand that this type of study of ocean noise was in its infancy in those days.  As it turned out, we learned something new about sound in the ocean every day as we looked further into the data—it was really an exciting time for us,” he said.

However, the sounds have never been conclusively identified. There are theories the sounds were made by Antarctic Minke whales, since the sounds were also recorded in Antarctic waters in later years, but there was no independent evidence from visual sightings of the whales making the sounds in the New Zealand data.

No matter the animal, Chapman believes that the sounds could be a conversation. The data was recorded by an acoustic antenna, an array of hydrophones that was towed behind a ship. The uniqueness of the antenna allowed the researchers to identify the direction the sounds were coming from.

“We discovered that there were usually several different speakers at different places in the ocean, and all of them making these sounds,” Chapman said. “The most amazing thing was that when one speaker was talking, the others were quiet, as though they were listening.  Then the first speaker would stop talking and listen to responses from others.”

He will present the waveform and spectrum of the recordings during his session, as well as further evidence that the work was a conversation between multiple animals.

“It’s always been an unanswered issue in my mind,” Chapman said. “Maybe they were talking about dinner, maybe it was parents talking to children, or maybe they were simply commenting on that crazy ship that kept going back and forth towing that long string behind it.”

Do pipe organs create an auto-tune effect? #ASA187

Pipe organs create sympathetic resonance in concert halls and church sanctuaries

Acoustical Society of America

 

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Ashley Snow studied the resonant effects of the D-K Organ on concert hall acoustics at Coe College in Cedar Rapids, Iowa.

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Credit: Ashley Snow

MELVILLE, N.Y., Nov. 20, 2024 – The pipe organ, with its strong timber base and towering metal pipes, stands as a bastion in concert halls and church sanctuaries. Even when not in use, the pipe organ affects the acoustical environment around it.

Researcher Ashley Snow from the University of Washington sought to understand what effects the world’s largest class of musical instrument has on the acoustics of concert halls that house them.

“The question is how much the pipe organ contributes to an acoustic environment—and the bigger question is, what portion of music is the acoustic environment, and vice versa?” Snow said.

Snow will present data on the sympathetic resonance of pipe organs and its effect on concert hall acoustics on Wednesday, Nov. 20, at 11:00 a.m. ET as part of the virtual 187th Meeting of the Acoustical Society of America, running Nov. 18-22, 2024.

Snow hypothesized that the pipe organ creates an auto-tune effect since its pipes sympathetically resonate to the same frequencies they are tuned to. This effect may enhance the overall musical sound of ensembles that play in concert halls with organs.

A sine-sweep—a resonance test in which a sine-wave shaped signal is used to excite a system—was played through loudspeakers facing the organ pipes and measuring the response with a microphone at different positions. Data was gathered by placing microphones inside and around the organ pipes during a musical performance and a church service.

“I was way up in the ranks dangling a probe microphone into the pipes, trying my hardest not to make a sound or fall,” Snow said.

Snow verified experimentally that sympathetic resonance does occur in organ pipes during musical performances, speeches, and noises at frequencies that align with musical notes, and that the overall amplitude increases when the signal matches the resonance of one or more pipes.

Investigation into the significance of these effects on the overall quality of musical performance to listeners in the audience is still ongoing. Snow hopes to expand this research by comparing room acoustics between rooms with and without the presence of an organ, along with categorizing and mathematically modeling the tuning system of various world instruments. “What about the sympathy of a marimba, cymbal, or piano strings? Or the mode-locking of horns in a band? Would it sound the same if these things were separated from each other? For better or for worse? I want people to think about that.”

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Media are invited to attend a virtual press conference about this research and other sessions on Monday, Nov. 18. A full schedule is available at https://acoustics.org/asa-press-conference-schedule-for-monday-nov-18-asa187. To register for virtual press conferences or sessions, email media@aip.org.

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Media are invited to attend a virtual press conference about this research and other sessions on Monday, Nov. 18. A full schedule is available at https://acoustics.org/asa-press-conference-schedule-for-monday-nov-18-asa187. To register for virtual press conferences or sessions, email media@aip.org.

———————– MORE MEETING INFORMATION ———————–

​Main Meeting Website: https://acousticalsociety.org/asa-virtual-fall-2024/  
Technical Program: https://eppro01.ativ.me/src/EventPilot/php/express/web/planner.php?id=ASAFALL24