The CBI had last week moved an application before the court seeking her voice samples for verification as it has got hold of some call records after taking over the investigation in the sensational murder mystery.
"I give my consent for the test," she told the court.
Magistrate R V Adone had allowed CBI's application and directed that jail manual be followed while conducting the voice sampling test.
The court then asked her to wait for the special public prosecutor to arrive.
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"I will give my consent, but I want to know that this (voice sample test) is to match with what?" she asked.
Patil told Indrani that her voice samples are needed to match with some voices.
When Indrani sought to know more, Patil told her she was not supposed to know it and that it was part of the investigation.
43-year-old Indrani, her former husband Sanjeev Khanna and her driver Shyam Rai were last week remanded in judicial custody till November 7 in the murder case.
They have been arrested on the charge of murdering 24-year-old Sheena, daughter of Indrani, and disposing of her body in a Raigad forest in April 2012.
The case is being probed by CBI after the Maharashtra government had sought its transfer from Mumbai Police to the central investigation agency.
Indrani, wife of ex-CEO of Star TV Peter Mukherjea, was recently hospitalised after her platelet count dipped drastically. But she was discharged soon after doctors at JJ Hospital found that she was not suffering from dengue as suspected.