The Iterative Signal-Based System (ISBS): Structuring Bioacoustic Data for Interpretable Identification

What this was about

Pankowski presented ISBS, a hybrid neural-symbolic framework for classifying cetacean vocalisations from passive acoustic monitoring. It works in three phases: detection (manual now, neural detection in progress), description (45 acoustic descriptors plus contextual metadata such as location and recordist), and classification with IKBS, a symbolic knowledge-based system from his lab. A proof of concept on over 500 events from the Watkins marine mammal sound database classified vocalisations into harmonic, impulsive and stationary acoustic domains. In Q&A an audience member explained that Camtrap DP is being adapted as a TDWG standard for bioacoustic data.

Why it matters. Neural classifiers are opaque, and there is no consensus on how to describe cetacean calls. A descriptor-based, interpretable approach could support a shared ontology of vocalisations and studies of how calls vary over time and between populations.

In the room

• Passive acoustic monitoring yields weeks of recordings with sparse events (e.g., minke whales detectable 100 km or more away), so manual processing is very time-consuming.
• Neural networks classify well but lose the information on why a call is classified as it is. Annotators also disagree on how many vocalisations a spectrogram contains, and there is no international consensus.
• Detection: neural approaches are acceptable for detection because explainability matters less there. Manual detections supply known cases for the knowledge base, and boat noise is a major problem.
• Description: 45 acoustic descriptors (temporal, spectral/frequency, cepstral) plus contextual metadata such as recording location and recordist, together with any expert annotations.
• Classification uses IKBS, a knowledge-based system developed about 20 years ago in the lab for corals and turtles and adapted here to vocalisations.
• Proof of concept: Watkins marine sound database, seven cetacean species seen around Reunion, more than 500 events, classified into harmonic, impulsive and stationary domains or combinations. Results were described as promising; the transcribed accuracy figure is garbled.
• Next: classify vocalisation types rather than species. The long-term hope is individual-level recognition and a consensus ontology of cetacean vocalisations.

Notable moments