sound/auditory methods are an acceptable way for shinobi though the restrictions are you need to have the Sound Release skill.
To use easier terms, genjutsu is induced through user chakra affecting opponent chakra. Therefore my question was how do you get your chakra to affect your opponent aside from ordinary hand seals or the use of dojutsu kekkei genkai? As an Uchiha and now going for Mangekyou Sharingan permission you'll need to more adept in your knowledge of genjutsu else you'll disgrace the mere attempt. Nevertheless I'll answer this and we'll proceed since I'm sure you'd like to proceed a bit further and have a stronger knowledge of genjutsu for future endeavors.
anyway you can think of getting your chakra into your opponent is a way in which you can induce genjutsu. chakra for genjutsu is taken from point A to B through aided by hand seals and/or precise chakra control. Any other way of inciting an A to B transfering of the chakra to your opponent is a way to activate it. The five senses; visual, auditory, olfactory, tactile, taste. These are all ways in which you can induce genjutsu. Affecting visual stimuli with your chakra, using sound waves to carry your chakra, using strong smells and scents to carry your chakra, physically touching your opponent, and however the hell taste is used. Nevertheless, none of these ways are implemented in our RP canon, this is more so for whenever you decide to submit your own genjutsu. Figuring out how you want to cast genjutsu and trap your opponent is part of the process. As well, being weary of people who have genjutsu with these factors in mind and knowing how to avoid/defend against them since they are not the most traditional kinds of genjutsu.