+1 for capslocks instructions. Any court-use of the recordings means your submitting transcripts.
It's kinda pricey to have a service transcribe them...you can do them yourself, but be very sure that you simply transcribe the words and don't embellish the transcription such as:
* Never using CAPSLOCK to EMPHASIZE a point
* Never using any font styling such as
italics or
bold to emphasize a point
* The only emphasis you get to use is punctuation, such as an exclamation point (and then..only use one!!!!

) and in such a case, the voices on the recording better be very obvious that they're yelling.
It can take a long time to transcribe for the non-pro at it...like 3-5x longer than the actual recording. If you can't make out a word, then insert [unintelligible] on that spot on the transcription. In practice, you'll have several unintelligible spots.
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Courts hate hearing recordings. Law enforcement hates hearing recordings. Nobody wants to hear them. It's not like Hollywood. Introduce a recording and the other side will pull out a typical bag of tricks to stop you such as:
* You only recorded part of it out of context
* You're trying to entrap the other person
* You're paranoid/controlling/the bully/etc. simply because you're recording (nevermind that the court, law enforcement, etc.....all record and nobody bats an eye about it)
Nevermind that the above is all false and that by somehow you recording caused the other parent to behave badly. But if you're methodical, record always, and use your recording to a good strategy, you can mitigate all those and have the recording (transcript) used.
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Strategy
Your overall strategy has to tell the court a story.
* The story must be stupid-simple to follow
* The story must not deviate into side stories
* The story must show that your proposed plan is better than the NJ's proposed plan. Not that she's evil incarnate..just that your plan is......better.
Proving perjury
The above example of using a recording to prove the NJ has committed perjury is one of the best uses. One of the few things the court hates more than recordings is people lying to the court. The court hates to be dissed. However, due to timing, it's not like things are on TV where Perry Mason asks the witness...then introduces the recording. In court, you'll need to submit your evidence well ahead of time (like 30+ days) and the other side gets a copy at that time too. So the other side will totally prep (rewrite) their strategy to deal with the content of the recordings so that they don't get caught lying. However....if there is more than one court hearing over time...then sure...you can prove that NJ committed perjury in some previous occasion....as long as everything stays on the topic of your story.
Proving NJ is a mean-yelling-evil-name-calling-shrew
Most all courts don't care at all about this and this would likely be a waste of time.
NJ making admitting to breaking court-orders (or admitting to crimes)
This can go under "dissing the court" and possibly perjury.