Interpretation of a voice recording could determine the result of Gable Tostee's murder trial.

The Brisbane jury is expected to retire today to decide whether the 30-year-old murdered Warriena Wright by intimidation.

She fell while climbing down the balcony from Tostee's Surfers Paradise apartment in August 2014.

Correspondent Sarah Motherwell said the judge will sum up today, and the decision rides on Tostee's cell phone audio.

"The fact that they fought, they fact that she screamed 'no' repeatedly before her death, and that final moment, as he closed the door on her, saying he would let her go, but "you've just been a bad girl."

Another factor is the alleged choking of Wright.

The prosecution alleges Wright was choked for 45 seconds beforehand.

Motherwell said there's no evidence on Wright's body, only audio from Tostee's phone.

"Miss Wright is no longer talking, and there's sounds of her gurgling and laboured breathing. They're alleging in that moment that Tostee is restricting her in some sort of choke hold."