I'd say maybe the voices in ones head need to be tested against the word of God,
First of all, Jesus Christ is the word of God, not the Bible. Yet through Isaiah the Lord explained that if you didn't listen to Him then the word of the Lord you would be order on order, line on line, here a little and there a little and that so you would going falling backwards, be snared and taken captive.
So if you mean tested against the orderly lines of the Scriptures then it is you who has been taken captive, just like Isiaih wrote!
If you do mean that we need to test what we hear with our Lord Jesus Christ, and I don't think your writing was meant to mean that, but if you did mean to check what you hear with Jesus Christ then you would be correct!! Are we not told to take all thoughts captive to Jesus Christ? Yes, but you didn't mean that and you don't really believe that if you seek Him you will find Him, even though that too is written in the Bible. Also there is a very specific test to you for testing the spirits according to what is written in the Bible, that you we should know, right?
1 Jn 4:1-3 Beloved, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world. By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God; and every spirit that does not confess Jesus is not from God; this is the spirit of the antichrist, of which you have heard that it is coming, and now it is already in the world.
So do you use that test at times? Can you even hear with your spiritual ears to you that test?
I have used it a lot, and it is pretty weird when you do use it. I would hear a voice talking to me and ask that spirit to tell me to " that confesses that Jesus Christ has come in the flesh" and while about 90% of the time I would get that confession and quickly, but sometime that spirit just disappear, and amazingly I would sometime hear the spirit actually tell me, "I can't tell you that." There were also times when asking for the confession would just infuriate the spirit and they would get upset with just the asking before leaving. BTW, you can stop that in a hurrying if you want. And probably the most amazing thing was when they would tell you something like, "I don't have to tell you that", and try to just keep on trying to tell you what they were trying to tell you.
There are other issue you come up against when testing the spirit like it written, but they are handled by then calling upon the Lord Jesus Christ and getting help and advice from Him - and that actually brings us back to what you kind of stumbled into - which is taking all thoughts captive to Jesus Christ. But again, that wasn't really what you were talking about, but was what you were actually doubting, right?
Did you not read that all those who seek find? Or perhaps you might have read in the Bible where Jesus talked about if you ask for bread, egg, or for a fish?
Luke 11:11 - 13 “For everyone who asks, receives; and he who seeks, finds; and to him who knocks, it will be opened. “Now suppose one of you fathers is asked by his son for a fish; he will not give him a snake instead of a fish, will he? “If you then, being evil, know how to give good gifts to your children, how much more will your heavenly Father give the Holy Spirit to those who ask Him?”
And so if you really want to know about discernment of spirits you really need to practice using your spiritual senses for a while to learn all this from the Lord!!!
Heb 5: 11 Concerning him we have much to say, and it is hard to explain, since you have become dull of hearing.
Heb 5: 13,14 For everyone who partakes only of milk is not accustomed to the word of righteousness, for he is an infant.
But solid food is for the mature, who because of practice have their senses trained to discern good and evil.
People write things without actually seeking and listening to the Lord our God Jesus Christ. So they scoff at the idea of hearing from Him! They think by their own understanding of the Bible they can figure out what the devil's are doing around them. But that is not accomplished by leaning on your own understanding, and not even your own understanding of the Bible!! Then the Bible is correct, but they are not!!
If you want to try and get good at discernment, start trying to hear from Jesus Christ our Lord and what He tells you via the Holy Spirit give His words to your spirit. And here is the kicker - if you practice listening to Him and give it some time, like say 20 years or so, then you will get some maturity, and with that comes the understanding that you are never going to be good enough at discernment of spirit to not need to seek Jesus Christ and what He has to say!!! You really have to go back to taking all thoughts captive to Jesus Christ and Him and the Word of God, meaning that you actually listen to Him!!
If you practice listening to the Lord you will understand the real meaning of this Proverb!:
Prov 3:5 Trust in the LORD with all your heart
And do not lean on your own understanding.
and
Prov 3: 6In all your ways acknowledge Him,
And He will make your paths straight.
and
Prov 3:7 Do not be wise in your own eyes;
Fear the LORD and turn away from evil.
And don't get confused - leaning on your own understanding of the Bible is still leaning on your own understanding!! You have to listen to Him and His voice for real understanding!!
Prov 2:'6 For the LORD gives wisdom;
From His mouth come knowledge and understanding.
Now - which word of God were you planning on testing against???
Rev 19:13 He is clothed with a robe dipped in blood, and His name is called The Word of God.
Hopefully you were talking about taking what you heard with your spiritual ears to Jesus Christ whose name is called "The Word of God:, because He speaks and His sheep hear His voice!! If not make it so!