The detection of echolocation clicks is key in understanding the intricate behaviors of cetaceans and monitoring their populations. Cetacean species relying on clicks for navigation, foraging and even communications are sperm whales (Physeter macrocephalus) and a variety of dolphin groups. Echolocation clicks are wideband signals of short duration that are often emitted in sequences of varying inter-click-intervals. While datasets and models for clicks exist, the detection and classification of clicks present a significant challenge, mostly due to the diversity of clicks' structures, overlapping signals from simultaneously emitting animals, and the abundance of noise transients from, for example, snapping shrimps and shipping cavitation noise. This paper provides a survey of the many detection and classification methodologies of clicks, ranging from 2002 to 2023. We divide the surveyed techniques into categories by their methodology. Specifically, feature analysis (e.g., phase, ICI and duration), frequency content, energy based detection, supervised and unsupervised machine learning, template matching and adaptive detection approaches. Also surveyed are open access platforms for click detections, and databases openly available for testing. Details of the method applied for each paper are given along with advantages and limitations, and for each category we analyze the remaining challenges. The paper also includes a performance comparison for several schemes over a shared database. Finally, we provide tables summarizing the existing detection schemes in terms of challenges address, methods, detection and classification tools applied, features used and applications.

翻译：回声定位信号的检测是理解鲸类复杂行为及监测其种群数量的关键。依靠回声定位信号进行导航、觅食甚至通信的鲸类物种包括抹香鲸（Physeter macrocephalus）和多种海豚群体。回声定位信号是短时宽的宽带信号，通常以变化的脉冲间隔序列形式发射。尽管目前已有相关数据集和模型用于处理这些信号，但由于信号结构的多样性、多个动物同时发声造成的信号重叠，以及来自例如枪虾和船舶空化噪声等非目标噪声瞬变的干扰，使其检测与分类仍面临重大挑战。本文系统综述了自2002年至2023年间提出的多种回声定位信号检测与分类方法。我们根据方法论将所调查的技术划分为若干类别，具体包括：特征分析（例如相位、脉冲间隔、持续时间）、频率分析、能量检测、有监督与无监督机器学习、模板匹配以及自适应检测方法。本文还综述了用于信号检测的开源平台以及可供测试的公开数据库。针对每篇文献，文中详细说明了所采用方法的细节、优势与局限性，并对每类方法分析了尚存的挑战。此外，本文在共享数据库上对多种方案进行了性能对比。最后，我们通过表格形式，从所应对的挑战、方法、检测与分类工具、所用特征及应用场景等方面，总结了现有的检测方案。