Post #62 elaborated clearly the scope for the sound engineering. It is the acoustic study. In short, the field study the characteristics of the sound wave, exploitation of the sound wave characteristic, generation & transmission of the sound waves. There are easily 3 type of disciplines involves :-

1) Treatment of the sound / background noise level / echo / reverberation - material for the floor, walls, ceiling. More related to architectural.
2) Treatment of noise / vibration - dampening / destruction of unwanted sound wave. More related to mechanical engineering.
3) Generation of sound, amplifying of sound, transmission of sound & receiver of sound. More related to the electrical engineering under the sub-category of extra low voltage services.

There are a few acoustic consultant in the market. if not mistaken, the Prahkun Acoustic is quite welll known for this field. You can check on their website. http://www.prakhun9.com/

Same, for a sound engineer to give the best, you need to study all. You cannot study a fraction of it & claim you are sound engineer. Whatever mixer or audio equipment you are providing will not give the best performance if you do not know how the surrounding affect the transmission of the sound. A simple echo / reverberation will screws up your solution & you will look like a crap. Like it or not, sound engineering will covers all that aspects.

If you only interested on the electronic part, it will leans more towards the electronic engineering instead of sound engineering.