According the sources, the prosecution filed an application seeking voice samples of Lakhvi and the other accused in view of a request made by Indian authorities.
The application is expected to be taken up at the next hearing on Aug 28.
Indian authorities had asked the voice samples of the accused so that they can be matched with recordings of Pakistan-based handlers, who were coordinating the actions of the 10 terrorists who carried out the attacks in Mumbai on Nov 26, 2008.
The trial has been conducting behind closed doors in the heavily-guarded Adiala Jail in Rawalpindi for security reasons.
Lakhvi and six other suspects have been charged under the Anti-Terrorism Act, Pakistan Penal Code and a cyber crimes law.
They have been accused of planning and facilitating the attacks on India's financial hub that killed 166 people in Nov 2008.