Invitation to the Institute of Acoustics, UK
In 1995 the organizers of the Sonar Transducer '95 conference from the University of Birmingham, UK invited me to present a paper on North American developments in the field of high-power sonar transducer design. I asked my American colleague Jan Lindberg from the Naval Undersea Warfare Center in New London, CT to coauthor this work and he readily accepted. Our paper on the state-of-the-art in Canada and the United States was well-received. The proceedings cover is shown here.
- "Recent transduction developments in Canada and the United States", D.F. Jones and J.F. Lindberg, Sonar Transducers '95, Proceedings of the Institute of Acoustics, 17(3), pp. 15-33 (1995).
Playback Experiments With Whales
By 2000, my broadband barrel-stave transducer was incorporated into a portable underwater transmitter system capable of producing sound in a relatively wide audio frequency band. This sea-going equipment, known as the Broadband Acoustic Transmission System (BATS), was developed in collaboration with my long-time contractor Sensor Technology Limited in Collingwood, Ontario.
I had built a close relationship with marine mammal experts at the Hal Whitehead Laboratory in the Department of Biology at Dalhousie University in Halifax and they borrowed BATS for vocal mimicry experiments with pilot whales off the coast of Cape Breton, Nova Scotia in the summer of 1999. We gave a paper at the 139th Meeting of the Acoustical Society of America in Atlanta, Georgia in 2000, and published a paper in Sea Technology magazine:
- "Playback experiments with long-finned pilot whales using a new broadband transmitter", D.F. Jones and L.E. Rendell, Journal of the Acoustical Society of America, 107(5), Pt. 2, May 2000, p. 2774.
- "Broadband acoustic transmitter for marine mammal applications", D.F. Jones and L.E. Rendell, Sea Technology, 41(8), August 2000, pp. 10-14.
Sluice the Trapped Humpback Whale
I was monitoring the news about a humpback whale that swam through the sluice gates of the Annapolis Tidal Generating Plant in Annapolis Royal in August 2004. The whale was putting on quite a show for the spectators, who gathered on the causeway over the Annapolis River to watch and take photos as it breached and played around each day. After about a week I contacted the Department of Fisheries and Oceans to offer my assistance to help lure the whale back through the sluice gates using my portable BATS transmitter and humpback whale calls.
This was not my idea, it was done successfully before with Humphrey the humpback whale who swam into San Francisco Bay and up the Sacramento River in 1985. I contacted the marine mammal researchers involved in that rescue and they sent me extensive notes concerning their efforts. They had obtained audio recordings of humpback whales on feeding grounds in Alaskan waters from the University of Alaska so I did the same. One of those recordings was very similar to my recordings from sea trials in the Bay of Fundy. This recording would be my Plan B.
I drove to Annapolis Royal with all my gear early one morning and set everything up near the bow of the small fisheries patrol boat manned by two crew. For anyone who has a picture of the guy sitting in the bow, that's me! I also had a hydrophone and headset so I could listen to everything underwater. I did an interview with one outlet before departing. We set off upriver from the causeway, which was packed with onlookers and media. When we found Sluice 'he' was headed back to the sluice gates so we did not have to broadcast anything underwater. We followed Sluice to the gates but by this time water was pouring through as the Bay of Fundy tide was coming in. There was no chance any marine mammal could swim through the oncoming torrent of water, and besides, Sluice was about to be served a fresh fish dinner!
At this point, Plan B kicked in and my idea was to make the relatively quiet underwater river environment sound like the Bay of Fundy. I did that for quite some time and at one point Sluice came right up to me to check out the sounds I was broadcasting (see the Nova Scotia Power press release below). That was the only time I heard his voice - briefly, just one call! My hope was that Sluice would be a bit homesick and would leave when the tide turned. We also broadcast these same whale vocalizations on the ocean side of the gates but these sounds would likely have not been heard on the river side over the sounds of the water rushing through the gates.
In the morning I returned to the patrol boat from my hotel and we set off to find Sluice. Only one reporter was there and we talked casually for a bit. We sailed almost 20 km, all the way to Bridgetown where the river became very narrow. There was no sign of the whale. I could not detect any whale vocalizations either. We assumed he had left the river overnight. Unfortunately, I cannot take any credit for success because we had a very loud thunderstorm that night and the marine mammal experts I talked to in the days to follow, had no idea how a whale in a quiet shallow river would react to loud thunder.
I left for Dartmouth but a few days later, as I recall, Sluice returned to the river only to leave again on his own. I made a second trip to the river to see for myself that he wasn't there any longer. This was the story from my perspective - a story never told in print until now.
"Nova Scotia Power press release: Sluice Update, Sep 02, 2004
Annapolis Royal, NS - The humpback whale that entered the Annapolis River via the sluice gates of the Annapolis Tidal Power Plant on Aug. 23 remains in the river and its activity level continues to suggest the whale is in good condition, is under no undue stress and has ample access to food such as herring and mackerel, which enter the river at high tide.
On Aug. 30-31, the Department of Fisheries and Oceans (DFO) in collaboration with Defence Research and Development Canada (DRDC) broadcast the sound of feeding humpback whale vocalizations in waters on both sides of the sluice gates in hopes this would coax the whale into returning to the Annapolis Basin and its natural habitat in the Bay of Fundy. Although the whale took interest in these sounds, even circling one of the transmitters, it did not exit the river. Nova Scotia Power has decided not to run the Tidal Plant this weekend."
Acoustic Bar Codes
An experiment using a signal I called acoustic bar codes (ABCs) was tested near the Berry Islands in the Bahamas and near the Western Bank on the Scotian Shelf using my BATS transmitter. The ABC signal was made-up of the ambient noise of the ocean plus information in the form of "silent bars". These experiments were presented at the 150th Meeting of the Acoustical Society of America in Minneapolis, Minnesota in 2005. It was such a novel idea that the conference committee selected it for a Lay Language Paper for the press and general public (see website link below).
- "Preliminary investigation of acoustic bar codes for short-range underwater communications", D.F. Jones, Journal of the Acoustical Society of America, 118(3), Pt. 2, September 2005, pp. 2038-2039.
- "Communicating underwater using natural ocean noise", ASA 150th Meeting Lay Language Papers, 2005. Website Link: https://acoustics.org/pressroom/httpdocs/150th/Jones.html
Hurricane Juan Paper
When Hurricane Juan made landfall in Nova Scotia on September 28, 2003, we were living in Dartmouth. The strongest winds in the eastern eyewall of the storm passed directly over Halifax. At 9:30 p.m. I was setting up audio recording equipment upstairs to capture the sounds of Juan as it passed over our house. At the same time, meteorologist Chris Fogarty from the Canadian Hurricane Centre was boarding a reconnaissance flight at the Halifax International Airport (now the Halifax Stanfield International Airport) to drop air-launched dropsondes into the storm.
From my audio recordings I was able to determine wind gust frequencies at different times throughout the night, and even captured the sounds of nearby trees breaking. As it happened, Chris and I became aware of each others measurements and wrote a unique paper combining his wind data with my acoustic data, and even explained how these trees broke. The paper appeared in Acoustic Research Letters Online, a web-based publication of the Acoustical Society of America.
- "The acoustic heartbeat of Hurricane Juan", D.F. Jones and C. Fogarty, Acoustic Research Letters Online, 6(2), April 2005, pp. 85-91.
Hermit Thrush Paper
Beginning in 2003 I became interested in the vocalizations of bird species. I recorded many of them in my travels around the province. By far the most intriguing vocalizations were those of the Hermit Thrush that migrated to Nova Scotia in the spring each year. What I noticed as I studied their song structures using audio editing software (spectrographic analysis), was that each Hermit Thrush had its own repertoire of songs, and no two birds sang even one identical song. This made me wonder if I could identify a single individual from one migration year to the next. And so, an experiment was undertaken.
I recorded more than 4000 songs from 17 Hermit Thrushes at 11 sites in and around the Halifax/Dartmouth metropolitan area from April 2003 until July 2006. My experiment went longer than the two consecutive years I had planned (2003-2004) because Hurricane Juan (September 2003) essentially destroyed the habitats where the birds made their homes in 2003. I had to start again in 2005 then see if the birds returned to the same locations in 2006.
Two of the birds in 2005 did return to their exact locations in 2006 and I recognized every single one of their songs from the year before using my audio analysis software. Both birds sang their own repertoires - not one new song nor one forgotten! I published a paper on this first-of-its-kind Hermit Thrush voice-print in the Journal of the Canadian Acoustical Association:
- "Voice-printing the Hermit Thrush (Catharus Guttatus), D.F. Jones, Canadian Acoustics, 34(3), September 2006, pp. 14-15.