Is it a condition for a supplication to be uttered aloud for it to be answered, and is the lack of specific intent in a supplication (such as praying for a job and being granted a job without pay, when one intended pay) among the reasons for not achieving the desired outcome?

Allah Almighty is aware of a person's intention and knows what their soul whispers, as He says: "And We have already created man and know what his soul whispers to him, and We are closer to him than [his] jugular vein" and "And He knows what you conceal and what you declare. And Allah is Knowing of that within the breasts." Supplication is the essence of worship, and for the one who supplicates, there are three outcomes: either the supplication is answered, or a calamity is averted, or the reward is stored for the Hereafter. And no soul will die until it has completed its provision.