How much will I get out of this if I'm in a position where I can't always sound out the words I'm learning?

[John Brooks]

My plan for these lessons is to use the hours of freetime I'm given with my job.
I work in a warehouse babysitting machines making sure they run properly. Very mind numbing boring work. I've used this time to get through several novels via audiobooks. I've also managed to learn spanish using audio lessons in conjunction with corrections fed by spanish speaking employees.
What I'm concerned with in these lessons is that I will be in a bit of an embarrassing situation if I'm constantly muttering "Toire wa, doko?" to myself. Will I not get the full effect from these lessons if I don't draw attention to myself while I'm not alone?

[Sai]

speaking the words out loud is essential when learning a new language i would think, pronouncing words in your head isnt the same as doing it out loud, its more difficult and when you speak the language aloud and it also becomes more familiar and coherent, that's what i think.