Bioacoustics & Ecoacoustics Glossary

Quality index (or index signal)

https://glossary.acousti.cloud/quality-index

en

A signal that carries reliable information about the sender because its production is subject to an unavoidable physical constraint that reflects its anatomy, morphology, physiological capabilities, or health (e.g., the lowest fundamental frequency that can be emitted by a mammal is constrained by the size of its vocal cords).

Reference: [1] Mathevon (2023), The Voices of Nature: How and Why Animals Communicate, pp. 305–308.