Elephants have their only ability to warm nearby or far herds of an inpending danger. All these can be done through acoustic, visual, chemical & seismic methods. Here are some of the sound they do make...https://www.elephantvoices.org/multimedia-resources/elephant-calls-database-contexts.html

Good day Lily.

I stumbled upon this post of yours.
Have you been able to make any advancement on this topic, or get any feedback from anyone?

I have been asked a similar question by a group, looking at early warning systems for large mammals, like elephants, of possible danger situations.

On my side, it is still a very new project, however, my use case has more to do with the trains that kills the elephants, but we also have a use case for early warning systems to recognize poachers and early warning systems to intercept any possible threat.

So if you are in a position, and willing to share any information, I would like to find out more, if there has been any developments regarding this topic aon your side.

Kind regards 
​Mischa

Hi,

Generating infrasound is generally energy intensive and expensive.  You can google "infra-subwoofer" and despair at the prices!  But those are for audiophiles.  I came across a fan type speaker design a long time ago that I think can be adapted,  Another possibility is to use pyrotechnics to generate infrasound, but that would not be reusable and I suspect development will be even more of a headache.  An intriguing possibility is to use basically a fogger - - those noisy smoky fumigators -- but built to produce the lower frequency.