title: Acoustic property reconstruction of a pygmy sperm whale (Kogia breviceps) forehead based on computed tomography imaging.
abstract: Computed tomography (CT) imaging and sound experimental measurements were used to reconstruct the acoustic properties (density, velocity, and impedance) of the forehead tissues of a deceased pygmy sperm whale (Kogia breviceps). The forehead was segmented along the body axis and sectioned into cross section slices, which were further cut into sample pieces for measurements. Hounsfield units (HUs) of the corresponding measured pieces were obtained from CT scans, and regression analyses were conducted to investigate the linear relationships between the tissues' HUs and velocity, and HUs and density. The distributions of the acoustic properties of the head at axial, coronal, and sagittal cross sections were reconstructed, revealing that the nasal passage system was asymmetric and the cornucopia-shaped spermaceti organ was in the right nasal passage, surrounded by tissues and airsacs. A distinct dense theca was discovered in the posterior-dorsal area of the melon, which was characterized by low velocity in the inner core and high velocity in the outer region. Statistical analyses revealed significant differences in density, velocity, and acoustic impedance between all four structures, melon, spermaceti organ, muscle, and connective tissue (p < 0.001). The obtained acoustic properties of the forehead tissues provide important information for understanding the species' bioacoustic characteristics.
authors.affiliation: Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, People's Republic of China.
authors.forename: Zhongchang
authors.initials: Z
authors.lastname: Song
authors.affiliation: Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, People's Republic of China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Xu
authors.affiliation: Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, People's Republic of China.
authors.forename: Jianchen
authors.initials: J
authors.lastname: Dong
authors.affiliation: Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, People's Republic of China.
authors.forename: Luru
authors.initials: L
authors.lastname: Xing
authors.affiliation: Radiology Department, People's Hospital of Sanya, Sanya 572000, People's Republic of China.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.affiliation: College of Ocean and Earth Sciences, Xiamen University, Xiping Building, Xiangan South Road, Xiangan District, Xiamen 361005, People's Republic of China.
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, Xiamen University, Xiamen 361005, People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, People's Republic of China.
authors.forename: Songhai
authors.initials: S
authors.lastname: Li
authors.affiliation: Dove Marine Laboratory, School of Marine Science and Technology, Newcastle University, Cullercoats, North Shields NE30 4PZ, United Kingdom.
authors.forename: Per
authors.initials: P
authors.lastname: Berggren
mesh_terms: D000158:Acoustic Impedance Tests; D000162:Acoustics; D000273:Adipose Tissue / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D000825:Animal Structures / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D000818:Animals; D003238:Connective Tissue / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D004455:Echolocation / Q000502:physiology; D005152:Facial Muscles / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005260:Female; D006257:Head / Q000033:anatomy & histology*; D009296:Nasal Cavity / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D009928:Organ Specificity; D013016:Sound; D014057:Tomography, X-Ray Computed; D014907:Whales / Q000033:anatomy & histology* / Q000502:physiology