It is possible Reeva Steenkamp's screams on the night she was shot and killed by Oscar Pistorius were as loud as a plane's engine, a court has heard.

State Prosecutor Gerrie Nel questioned acoustic expert Ivan Lin on the sounds heard on Valentine's Day last year when the athlete's girlfriend was killed.

When asked if he would put Ms. Steenkamp's screams at 120 dB, Mr. Lin said "120 means extremely loud, you can almost hear it 100 metres away. It is a very slight possibility, but it is possible".

Reporter Emma Hurd said "Mr. Nel is trying to make the point that Reeva Steenkamp would have screamed loudly because she was 'screaming for her life'".

After quizzing Mr. Lin about some of the technical details in report, Mr. Nel contended that, without exception, everybody heard a woman's screams on that night.

He said "Four state witnesses all heard screams by a woman. That must be reliable even for a scientist".

Pistorius's defence team have previously said the screams came from him, as he was upset that he had killed Ms. Steenkamp.

Next to give evidence was Peet van Zyl, Pistorius's manager.

Mr. van Zyl, who has worked with the athlete since 2006, told the court Pistorius had a "heightened sense of awareness".

This led to him always parking his car in open spaces with plenty of lighting, sitting close to the door in restaurants and locking his hotel room door when he was travelling.

Mr. van Zyl recalled an incident on an airplane when Pistorius removed his prostheses because of severe blisters on his stumps.

"At some stage one of the legs fell over and when an airhostess tried to pick it up politely, Oscar Pistorius had felt someone close and (he) was startled" Mr. van Zyl said.

"He grabbed his leg from her".

Large parts of the trial have focused on Pistorius's relationship with Ms. Steenkamp, which had started around three months before her death.

Mr. van Zyl said their relationship was "loving and caring" and they were always calling each other pet names. Pistorius planned to take her to an Andrea Bocelli concert in Italy, Mr. van Zyl told the court.

It was revealed that Pistorius was moved from a room he was sharing with another athlete at the 2012 Olympics because, Mr. Nel said, Pistorius was constantly on the phone arguing.

Mr. van Zyl said he heard there was an issue between the pair, but was not aware why they did not get on.

Before the court adjourned for the day, Mr. van Zyl was asked if he though Pistorius was paranoid. He replied he was not qualified to offer an opinion.

The trial has resumed after an adjournment for a month of psychiatric tests, which found Pistorius was not mentally ill at the time of Ms. Steenkamp's death and that he is fit to stand trial.

Pistorius denies murdering Ms. Steenkamp, claiming he mistook her for an intruder in his home.