Here is the list of functions and classes that can be converted to C/C++ using MATLAB Coder: https://www.mathworks.com/help/coder/ug/functions-and-objects-supported-for-cc-code-generation.html
In particular, sonarEmission appears to be on that list, and the help page for this class confirms that it supports generation of C/++: https://www.mathworks.com/help/fusion/ref/sonaremission-class.html
Note that you can't just convert sonarEmission to C++. What you do is you write your own function that uses sonarEmission, and then you use MATLAB Coder ("codegen" command) to convert your function, and all other functions and classes it uses (including sonarEmission etc) into C/C++.
