Acoustics are increasingly regarded as a remote-sensing tool that provides the basis for classifying and mapping ocean resources including seabed classification. It has long been understood that details about the character of the seabed (roughness, sediment type, grain-size distribution, porosity, and material density) are embedded in the acoustical echoes from the seabed. This study developed a sophisticated yet easy-to-use technique to discriminate seabed characteristics using a split beam echosounder. Acoustic survey was conducted in Tongyeong waters, South Korea in June 2018, and the verification of acoustic seabed classification was made by the Van Veen grab sampler. The acoustic scattering signals extracted the seabed hardness and roughness components as well as various seabed features. The seabed features were selected using the principal component analysis, and the seabed classification was performed by the K-means clustering. As a result, three seabed types such as sand, mud, and shell were discriminated. This preliminary study presented feasible application of a sounder to classify the seabed substrates. It can be further developed for characterizing marine habitats on a variety of spatial scales and studying the ecological characteristic of fishes near the habitats.

Introduction
 Material and Methods
  Acoustic data analysis
  Depth normalization
  Seabed roughness (E1) and seabed hardness (E2)
  Key seabed features
  Seabed classification
  Data validation
 Results
  Seabed echogram and its property
  Ground truth of acoustic seabed classification
  Backscattering characteristic by seabed type
 Discussion
 Conclusion
 References

• Rina FAJARYANTI(Department of Maritime Police and Production System/Institute of Marine Industry, Gyeongsang National University)
• Myounghee KANG(Department of Maritime Police and Production System/Institute of Marine Industry, Gyeongsang National University) Corresponding author