Pretoria - Oscar Pistorius' voice, and his ability to scream at a certain level, is under the microscope at his murder trial this afternoon.
The defence called its second witness for the day, Ivan Lin, an electrical engineer who specialises in acoustic consultation.
He said he examines how human beings perceive sound.
Lin was asked by the defence to determine the difference between male and female screams from different distances, and is presenting his report to the High Court.
Some of Pistorius' neighbours told the court during their own testimony they heard the sound of a woman screaming on the night the athlete shot and killed Reeva Steenkamp. But Pistorius' defence team have argued that the sounds neighbours heard were actually the athlete himself in a state of extreme agitation.
Lin said there were no studies that suggested all female or male voices sounded the same.
He said that perception isn't always an accurate reflection of the original event, and numerous psychological factors could come into play when hearing such a traumatic set of sounds.
He added that people can't always differentiate between male and female screams.
The engineer said that it is incredibly difficult to exactly reconstruct the sound conditions of the night of the shooting.
He said he'd examined how the closed barriers, such as the bathroom window, the balcony and cubicle doors. Even meteorological or weather conditions could have affected sound.
Meanwhile, a missing piece of evidence stalled proceedings earlier today, with the state called on to identify what happened to it.
Prosecutor Gerrie Nel had asked another witness, Dr Gerry Versfeld about whether Pistorius would have had trouble maneuvering over an electrical cord on the ground while running on his stumps. The cord was also much discussed during Pistorius’s cross-examination.
Defence advocate Barry Roux asked the court to order the state to provide the cord, which he had previously asked for and not received. Nel said that the state did not have the cord and that it was never seized from the scene by investigators, and was never placed into their inventory.
A very displeased Judge Thokozile Masipa said that those responsible for sealing the house after the investigation should be asked to respond to the defence's queries on the location of the cord.
Lin said that from about 80 meters away on a balcony, an audible, maybe even intelligible sound could be heard from inside the toilet cubicle.
He did say however, that if the neighbours were more than 170 meters away, they would have been unlikely to hear the noises coming from the cubicle.
It would also be difficult to determine the emotion or gender of these screams from such a distance.
Prosecutor Gerrie Nel said because of the technical nature of Lin's testimony and because he only received his report today, he asked for time to properly examine the report and continue cross-examination on Tuesday.