Startling more easily has nothing to do with your ears, its a reflex...I have a real heightened sense of smell and awaiting for a referral as its affecting my breathing by clamping up my throat. I also can not tolerate certain materials on me or even near me as this also affects my breathing in the same way as smells.

The smell issue really amazes and baffles me as in ALS the neurons obviously die but with increased sense of smell the olfactory cells/neurons are multi-plying thus why you are able to smell certain smells others cant.

The proper name for increased sense of smell is Hyperosmia, I very much doubt you will find much info online as to the cause etc...

Good luck, and sorry to hear of your diagnosis.

Best wishes, Jeannie x