If one doesn't shout, but speaks loudly is as comprehensive in the eyes of G'd, for is it that G'd can't validate something aloud, and the same way as those things spoken silently? Certainly He can hear both, as we can see in Hannah's prayers to have a son (1 Samuel 1:10-13), and she had, the great Israel's Judge Samuel. Indeed, we see:
10 In her deep anguish Hannah prayed to the Lord, weeping bitterly. 11
And she made a vow, saying, “Lord Almighty, if you will only look on
your servant’s misery and remember me, and not forget your servant but
give her a son, then I will give him to the Lord for all the days of
his life, and no razor will ever be used on his head.”
12 As she kept on praying to the Lord, Eli observed her mouth. 13
Hannah was praying in her heart, and her lips were moving but her
voice was not heard. Eli thought she was drunk
Even though her voice wasn't heard, her movements was characterized by Eli, as being drunk by such movements, then, applying to the same context, depending on the situation, it can be that a person still speaking aloud can be blessed or bless other ones.
Just as another example, I quote (1 Corinthians 14:16):
Otherwise, if you give thanks with your spirit, how can anyone in the
position of an outsider say “Amen” to your thanksgiving when he does
not know what you are saying? (ESV)
However one can't expose by falsehood as it says (Matthew 6:5):
“And when you pray, you must not be like the hypocrites. For they love
to stand and pray in the synagogues and at the street corners, that
they may be seen by others. Truly, I say to you, they have received
their reward. (ESV)
Also, it's pointed out in 1 Corinthians 14:14 that one can't stand in vain thoughts:
For if I pray in a tongue, my spirit prays but my mind is unfruitful.
(ESV)
Another example is (Psalm 142:1):
A Maskil of David, when he was in the cave. A Prayer. With my voice I
cry out to the Lord; with my voice I plead for mercy to the Lord. (ESV)
King David also points out again (Psalm 77:1):
To the choirmaster: according to Jeduthun. A Psalm of Asaph. I cry
aloud to God, aloud to God, and he will hear me. (ESV)
So, if the loud prayer is in peace (not with anger), then it doesn't matter, in my perception, if it's loud or silently, and observing that the mind in silence can have the worst thoughts.