The forensic analysis conducted by Central Forensic Sciences Laboratory (CFSL) located here has said "there is continuity in the conversation".
"Recorded conversation is in continuity, no abrupt change in speech signal has been detected," police sources said quoting from the report.
They also said there was no no change in background voice pattern.
The purported telephone conversation among Shanti Bhushan, Yadav and Singh suggested attempts being made at influencing a judge.
However, S R Singh, Director of Truth Labs, which conducted its tests on behalf of Bhushan, maintained that he would stand by the report he had given that it was doctored.
The conversation had "multiple gaps and signs of electronic editing at very very critical places", Singh had said in his report.
The CD and its transcript were shown to complainant Shashi Bhushan, who is co-chairperson of the joint committee to draft the Lok Pal Bill, and got it countersigned by Bhushan before it was given to the lab for testing, they said.
Delhi Police spokesperson Rajan Bhagat said the case has been transferred to the special cell for investigations.
Sources said they may call in Bhushan for questioning in connection with the case. They also said the genuineness of the CD can be conclusively proved if they can find the original CD and compare it with the audio files.
The new report triggered a fresh round of war of words with Amar Singh demanding the resignation of Shanti Bhushan and Prashant Bhushan from the joint drafting committee on Lokpal Bill while civil society members raised doubts over the forensic test reports. .
Amar Singh said, "at least on moral grounds Bhushans should quit the panel (drafting panel) and Anna Hazare should replace them with someone more credible."
Countering Singh`s demand, human right activist Swami Agnivesh expressed surprise over two different report on the same CD.
"It is surprising that CFSL report claims the CD is not doctored. American experts have confirmed tampering, so CFSL report can not be trusted fully," he said.
"It is a conspiracy against the anti-corruption movement led by Anna Hazare. There should be an investigation as to how this CD from 2006 came out suddenly and who is responsible behind it," he added.
Agnivesh demanded the CD should be verified from more labs and authorities to get a common view.
Another member of the Lokpal Bill Drafting Committee Arvind Kejriwal refused to comment on the controversy.
"I don`t have to say anything. Talk to Prashant Bhushan. I am here to draft the Lokpal Bill. My motive is not to get into this. My motive is that the country gets a good anti-corruption law. I am devoting all my energies into it and dint want to divert," he said.
Meanwhile, Congress General Secretary Digvijay Singh commenting on the reports targeted Bhushan for getting the CD verified on their own.
"Shanti Bhushan does investigation on his own saying I am clean. This is a new way of investigating charges. I think this is intriguing that this crusaders of corruption, father-son duo, does not find corruption in allotment of two pieces of 1000 square meter land in Noida."
Police have also recovered the CD from an English newspaper which will be sent for forensic examination. The senior Bhushan in his complaint had mentioned that the newspaper reporter had approached him for his comments with the CD.
Police had earlier registered a case under Section 469 (forgery intended to cause disreputation) against unknown persons on a complaint filed by Bhushan, who alleged that the CD was forged and intended to malign his reputation and derail the process of joint drafting committee on Lokpal Bill.