The following from Campbell Clark June 6th article in the Globe and Mail:
Yesterday, Jack Mitchell, a U.S. forensic audio expert who conducted a preliminary review of portions of the originally released recordings, said they had been altered. He said he did not believe the changes occurred in the digital-copying process.
"These tapes have been edited. This is not a maybe. This is not something that's unexplained. This is not, 'Oh, this is odd.' This is a definitive statement. The tapes have been edited," Mr. Mitchell said.
He said he could not say with certainty how the alterations occurred, or conclude definitely that it was done intentionally.
However, Mr. Mitchell said that he not only found instances of possible edits, including sections where it appeared that phrases had been added to the recordings, but also a telltale repeat of a brief snippet of conversation that was repeated exactly.
"The entire thing repeats exactly. It's not the speaker repeating his phrase. This repeats exactly in the same way, with the same rhythm, with the same timing, with the same noise signatures. This is impossible," he said.
Mr. Mitchell said that he is not aware of such a glitch ever being produced in a digital transfer.
"I don't know how it could. I really don't," he said.
Errors in digital transfer can produce crashes that end the recording, or "dropouts" where brief gaps lasting a fraction of a second to a few seconds are created.
"But as far as it actually taking the digital file and sort of combining them and doing its own editing and changing things, I think that's nonsense. I've never seen it, I've never heard of a report of it."
The same repeat -- where Prime Minister Paul Martin's chief of staff, Tim Murphy, says "cup of tea" -- was found last week by Glen Marshall, a former RCMP engineer hired by the Liberal Party to examine the recordings.
Mr. Harper's communications director, Geoff Norquay, and his press secretary, Carolyn Stewart-Olsen, could not be reached yesterday.
Mr. Mitchell operates a forensic audio firm called Computer Audio Engineering in Albuquerque, N.M., which has done work used in court cases for U.S. federal prosecutors, several U.S. police forces, and prosecutors and defence attorneys.
He said he has not seen any reports of any other examination of the recordings, except a written statement issued by Mr. Dosanjh's office that alleges at least six sections of the tape were altered, which was sent to him by The Globe.
Mr. Mitchell reviewed two portions of the recordings where Mr. Dosanjh claimed to have found changes, totalling about eight minutes, to determine if there was evidence they had been altered.
The repeated "cup of tea" section is not on a new version of the recordings issued by the Conservatives last Thursday. Those new versions contain 14 minutes of new audio material -- pieces of conversations that are interspersed throughout the recording in a variety of places, which were missing from the first version that was released to the public.
Mr. Mitchell said he thought it was unlikely that such interspersed material was accidentally cut when it was copied to compact disc, as the Conservatives maintain.
"I've never heard of it. Is this something new taking place out there that I haven't heard of? Well, you know, that's always possible, but I don't think so. It would be all over the place if this happened. There are people out there making audio CDs all the time, and nobody has mentioned anything like this ever happening."
In addition, a section of another conversation reviewed by Mr. Mitchell, in which Mr. Dosanjh asserts that any arrangement made with Mr. Grewal "requires a certain degree of deniability" appears to have been edited in from another conversation, as Mr. Dosanjh had alleged. But Mr. Mitchell said it would take further analysis to determine that with certainty.
"The phrase is suddenly -- the amplitude is higher, the frequency content is different, meaning that essentially there are more bottom frequencies in it. The noise signature is different, and on either side of that phrase, they're the same."