Who has never heard sentences like: "You must cry out to God" or "I cried out to God and my prayer was answered".
It is true that the Bible speaks in various places about people crying to God; this practice is most often found in the Old Testament.

1 Samuel 7: 8 So the children of Israel said to Samuel, “Do not cease to cry out to the Lord our God for us, that He may save us from the hand of the Philistines.”

Psalm 34: 17 The righteous cry out, and the Lord hears, And delivers them out of all their troubles.

This practice of crying out to God was widespread in the Old Covenant, not only in prayers. People sometimes had to shout to inform, or to proclaim something.

Esther 6: 9 Then let this robe and horse be delivered to the hand of one of the king’s most noble princes, that he may array the man whom the king delights to honor. Then [a]parade him on horseback through the city square, and proclaim before him: ‘Thus shall it be done to the man whom the king delights to honor!’ ”

We can find examples where among the Hebrews, it was not unusual to shout or speak with a loud voice for things other than prayer.

Mark 10: 47 And when he heard that it was Jesus of Nazareth, he began to cry out and say, “Jesus, Son of David, have mercy on me!”

It was therefore not unusual to hear people screaming in the streets, in public places. In most cases, no one was offended or surprised. 
We can even see at times that God, addressing Jonah, asks him to shout against the city of Nineveh.

Jonah 1: 2 “Arise, go to Nineveh, that great city, and cry out against it; for their wickedness has come up before Me.”

In our present-day language, crying out means raising your voice loudly. You can cry out for various reasons: because of anger, in case of an emergency, to call someone, because of physical or moral pain, etc....
But we will see that when the Bible speaks of "crying out to God", we do not find exactly the same notion as in our current language.
Quite often the problem is that a majority of Christians have adapted “crying out to God” to the definition of our present-day language.
These same Christians then think that we should cry out when we pray, that we should cry out in a thundering voice when we speak to God.
But as I often say, God has no hearing problems.
It is the same pattern that comes up almost every time, everything is good so we don’t have to use our faith. Satan knows very well that faith is the only element that will give success to our prayers. Knowing this, he very often uses the same stratagem, and far too many Christians fall into this lie. If any person or teaching offers you to have your prayers answered without faith being a part of it, then my advice is to avoid this kind of way of thinking. 
We too often hear that all we need to do is to cry out to God, to pray with a loud voice to have our prayer answered, that is not what the Bible tells us.
The Bible says that God looks at what is inside us and not at external manifestations.
This is a major difference between law and grace. Those who know me often hear me say that: very often grace is the fulfilment in our thinking of manifestations that were tangible under the law. One could cry out to God under the law, but in this period of grace, to cry out to God is an attitude of the thought.

1 Samuel 16: 7 But the Lord said to Samuel, “Do not look at his appearance or at his physical stature, because I have refused him. For the Lord does not see as man sees; for man looks at the outward appearance, but the Lord looks at the heart.”

So it is not just the fact of raising your voice, of crying out to God who will change anything. God is not sensitive to appearances, He will never be impressed by decibels. Just because I will shout, or pray with a loud voice does not mean that my prayer will change anything.
The Bible also reveals to us that it is only through faith that we can obtain something from God. Only our faith is able to give us full access to the spiritual world which contains everything that God has planned to give us. The faith that is in me, once activated, is the element that opens everything from the spiritual world into my personal life.

Matthew 21: 22 And whatever things you ask in prayer, believing, you will receive.”

Jesus reminds us here that faith, this way of thinking that goes far beyond our 5 senses, this decision that we make to believe no matter what the circumstances, is the element that allows us to receive what we ask for when we pray.
There are also many passages that confirm that to cry out is not a solution in itself. In many places in the Bible we can see that people have cried out to God without any success. There are even examples where God Himself refuses to answer people who cry out to Him. 

Psalm 18: 41 They cried out, but there was none to save; Even to the Lord, but He did not answer them.

2 Samuel 22: 42 They looked, but there was none to save;  they cried to the Lord, but he did not answer them.

Job 30: 20 I cry out to You, but You do not answer me;…

Job 35: 12 There they cry out, but He does not answer, Because of the pride of evil men.

Job 35: 13 Surely God will not listen to an empty cry [which lacks trust], Nor will the Almighty regard it.

These few examples could be extended by other passages from the Bible.
But then where do we find ourselves in all these different examples, in all these different scriptures?
However, there are many teachings that recommend that we cry out to God, some testimonies from people who assure us that they have cried out to God and that their prayers have been answered.
When we read the Bible, we can also see a passage where, for example, God asks us to cry out to Him through a prophecy of Joel.

Joel 1: 14 Consecrate a fast, Call a sacred assembly; Gather the elders And all the inhabitants of the land Into the house of the Lord your God, And cry out to the Lord.

The New Covenant certainly does not contain as many examples, but we can nevertheless find some examples where people also talk about crying out to God. 

Luke 18: 7 And shall God not avenge His own elect who cry out day and night to Him, though He bears long with them?

If we had to say that we have to cry out to God thinking that it is a matter of a loud voice, then this passage also asks us to do it day and night. Here again the Bible shows us in many places that positive results in prayer are not a matter of time. I mean, just because I'm going to remain in prayer for a long time doesn't mean I'm multiplying my chances of success. Of course I can take more or less time to activate my faith, but what I mean is that the more or less long prayer in itself does not change the result.
Even the Holy Spirit cries out in this passage from Galatians:

Galatians 4: 6 And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying out, “Abba, Father!”

James 5: 4 Indeed the wages of the laborers who mowed your fields, which you kept back by fraud, cry out; and the cries of the reapers have reached the ears of the Lord of Sabaoth.

James also speaks here about people who have cried out and that God has paid attention to them.
So would it be necessary to shout to be able to call out to God?
Should we cry out to God our prayers for more success?
The answer is no, but that does not sometimes prevent us from having different sound levels when we speak to God. And that is where all the tenor of crying out to God lies.
When the Bible speaks of crying out to God mainly in the New Covenant, it is a state of heart, a state of thought.

Hosea 7: 14 They did not cry out to Me with their heart When they wailed upon their beds. “They [a]assemble together for grain and new wine, They rebel against Me;

What the Bible calls the heart is our way of thinking.  When God speaks through the prophet Hosea, He reveals to us that it is above all, in my way of thinking that I cry out to God. Crying out to God is a state of mind, a state of my spirit.
A person who screams as we said at the beginning of this teaching can do so for different reasons. But when we say that we cry out to God, it is in a particular attitude. When we are in this attitude there are several facets that we can describe as follows:
- Being in true humility
- Needing help
- Relying totally on God
- Having our faith activated
- Being in an attitude of renunciation or denying
- Having nothing more to lose

These different ways of thinking are the main ones and will position me in an attitude where I will be able to cry out to God. It is precisely because, and only because of this detailed attitude in this short non-exhaustive list, that I am in a position to receive.
- My faith is activated (I firmly believe without any doubt, no matter what the circumstances are)
- I am in humility realizing that God is much more capable than I am (supplication)
- I am beforehand in agreement with what God will say (humility)
- I do not necessarily seek my own interest, but the one of the kingdom (self-denial)
- Nothing is more important than my spiritual life.

When I am in this process, and only in this process, then according to the words that I pronounce, I will be led to different intonations of voices, more or less loud. Then I will be led to express proclamations, distress if I am in this case, trust in my Father, etc. All these attitudes, these thoughts will be able to be expressed according to the people, by whispers, sighs, cries, laughter, sung words, crying out to the way I feel these feelings in my spirit. 
Then I can say in this case that I cry out to God.
It is now easy for a new born again person to understand that when the Bible talks about crying to God, it is not about volume first. But the different intonations or volumes will only be the fruit or the by-product of what is inside me in my spirit.
We do not cry out to God with our voice so that a fruit may be created within us, and our prayer may be answered. But sometimes we raise our voices as a result of a strong thought that says that God is with me, ready to realize what He says about me in His word.

Psalm 119: 147 I rise before the dawning of the morning, And cry for help; I hope in Your word.

Bye for now.