Kershenbaum Arik, Roch Marie A
National Institute for Mathematical and Biological Synthesis, Knoxville, Tennessee 37996.
Department of Computer Science, San Diego State University, San Diego, California 92182.
J Acoust Soc Am. 2013 Dec;134(6):4435. doi: 10.1121/1.4828821.
Dolphins and whales use tonal whistles for communication, and it is known that frequency modulation encodes contextual information. An automated mathematical algorithm could characterize the frequency modulation of tonal calls for use with clustering and classification. Most automatic cetacean whistle processing techniques are based on peak or edge detection or require analyst assistance in verifying detections. An alternative paradigm is introduced using techniques of image processing. Frequency information is extracted as ridges in whistle spectrograms. Spectral ridges are the fundamental structure of tonal vocalizations, and ridge detection is a well-established image processing technique, easily applied to vocalization spectrograms. This paradigm is implemented as freely available matlab scripts, coined IPRiT (image processing ridge tracker). Its fidelity in the reconstruction of synthesized whistles is compared to another published whistle detection software package, silbido. Both algorithms are also applied to real-world recordings of bottlenose dolphin (Tursiops trunactus) signature whistles and tested for the ability to identify whistles belonging to different individuals. IPRiT gave higher fidelity and lower false detection than silbido with synthesized whistles, and reconstructed dolphin identity groups from signature whistles, whereas silbido could not. IPRiT appears to be superior to silbido for the extraction of the precise frequency variation of the whistle.
海豚和鲸鱼使用音调哨声进行交流，并且已知频率调制对上下文信息进行编码。一种自动化的数学算法可以对音调叫声的频率调制进行特征描述，以用于聚类和分类。大多数自动的鲸类哨声处理技术基于峰值或边缘检测，或者需要分析人员协助来验证检测结果。本文引入了一种使用图像处理技术的替代范式。频率信息作为哨声声谱图中的脊线被提取出来。谱脊是音调发声的基本结构，并且脊线检测是一种成熟的图像处理技术，很容易应用于发声声谱图。这种范式被实现为免费可用的Matlab脚本，命名为IPRiT（图像处理脊线跟踪器）。将其在合成哨声重建中的保真度与另一个已发表的哨声检测软件包silbido进行比较。这两种算法也都应用于宽吻海豚（瓶鼻海豚）特征哨声的真实世界录音，并测试它们识别属于不同个体的哨声的能力。对于合成哨声，IPRiT比silbido具有更高的保真度和更低的误检率，并且能够从特征哨声中重建海豚身份组，而silbido则不能。在提取哨声的精确频率变化方面，IPRiT似乎优于silbido。
