Fig 2 -

• Main Authors: Marie J. Zahn (11414012), Kristin L. Laidre (3227658), Peter Stilz (43450), Marianne H. Rasmussen (3340494), Jens C. Koblitz (11414015)
• Format: Still Image
• Language: unknown
• Published: 2021
• Subjects: Cell Biology; Neuroscience; Physiology; Ecology; Inorganic Chemistry; wider ventral beam; narrow beam width; high source levels; div >< p; calculate sonar parameters; 212 db pp; 120 meters distance; monodon monoceros </; delphinapterus leucas </; ranging animals using; acoustic programs throughout; 4 °; showing; wild belugas (<; situ </; narwhals (<; acoustic classification; 2013 using; wild belugas; west greenland; vertically scan; two locations; sea ice; scanning behavior; results provide; results indicate; recording equipment; pack ice; may differ; linear 16; findings support; evolutionary adaptation; effectively navigate; echolocation signals; clicks centered; captive contexts; captive belugas; baffin bay; axis clicks; 42 minutes; 04 hours; Baffin Bay; Greenland; Baffin; Beluga*; Delphinapterus leucas; Monodon monoceros; narwhal*; Sea ice
• Online Access: https://doi.org/10.1371/journal.pone.0257054.g002

Schematic showing experimental setup and spatial criterion for on-axis click selection in the (A) vertical and (B) horizontal planes. The radiation pattern of an echolocation click is shown where the passive sonar equation was applied. The source level (SL) is the sound pressure level calculated from the received level (RL) and transmission loss (TL) on the acoustic axis; apparent source level (ASL) is the sound pressure level calculated for off-axis clicks/clicks of unknown recording aspect. Vertical on-axis clicks were isolated when the whale’s acoustic axis (i.e. the maximal intensity of the whale’s beam) was vertically centered on the array which was determined by -3dB beam width calculations. For each scanning sequence (i.e. click train with first ascending then descending amplitudes), the highest intensity click was isolated as a horizontal on-axis click where the whale was pointing its beam towards the array (not to the left or right), assuming constant SL.