In 2021, scientists experimenting with fiber optics picked up a strange signal: the cacophony of cicadas. It could lead to a new way of monitoring insects.
Fibre optics can be used to measure a remarkable number of properties.
The electrical transmission industry makes significant use of fibreoptic current sensors, and distributed fibreoptic temperature sensors.
The latter is particularly useful as you can measure the temperature at any point along the fibre's length, allowing you to detect hot-spots in cables.
Cicadas are pretty loud; I'm sure you can pick up much quieter things with a fibreoptic microphone.