Last week I received a phone call from Guy Gordon, a WDIV TVR NBC affiliate here in Detroit, Michigan. He came to the Primeau Forensics office, bringing with him a recording of an unknown voice making certain remarks. Mr. Gordon asked us to perform a voice identification analysis on the recording. The assignment was to determine if Warren Mayor Jim Fouts was the voice speaking in this recording.
Mr. Gordon also brought some recordings with known samples of Mayor Jim Fouts speaking, which I compared with the unknown recording. I performed two forms of voice identification testing (also known as speaker recognition) with a second audio forensic expert employed with Primeau Forensics. We performed both aural spectral voice ID as well as biometric voice identification testing. After analyzing the results of the testing, we concluded that the voices were a probable match. The biometric software came back with a high probability of a match between the voices across the majority of the tests. The aural spectral method also showed high consistencies between the voices with very little difference in their pitch. I was asked to interpret the results in percentage of probability, and I reported an 80% chance that the unknown voice in the recording was that of Mayor Jim Fouts.
During a voice identification analysis, it is important that I stay unbiased and focus on the science of the investigation. I have no stake in the outcome of the testing and I make sure that anything I report is based on my data and analysis. This ensures that any other expert could perform the same tests and provide the same results.
It’s important to note that the test I performed would be considered a preliminary or emergency voice identification test. The reason I call it an emergency test is because an immediate analysis was required and we, therefore, had to use any available sample of the suspected person’s voice to perform the comparison. In an ideal voice identification analysis, we would create what is called an exact exemplar. This is a recording of the suspected person reading the same dialogue as spoken in the unknown recording. In this test, we used both an in-person interview with Mayor Jim Fouts, as well as a radio interview found online. For the purposes of this test, we were able to obtain accurate voice information from the found samples. Creating an exact exemplar would lend further credibility to the analysis and results.
In many cases, an emergency voice identification test is the best option after the event in question occurs. Sometimes the suspected party is not willing to create an exact exemplar, and in some cases, the client does not want to alert the suspected party of the testing until some results have been found. Threatening calls are especially difficult to deal with, as alerting the suspected person prior to any conclusive results can be dangerous. Providing these initial results can provide the company or client the support they need to take the proper steps forward.
In this case, the emergency voice identification test was the fastest way to get results so that other city officials could move forward. We performed all the available testing to compare the voice directly with known samples. My conclusions were based on the data and results that were calculated from the voice samples. By basing my conclusions on the data, I avoid as much bias as possible so that the results are objective. High consistencies were observed between the unknown evidence recording in question and the two sample recordings we had available. The pitch comparison, formant comparison, and biometric comparison all showed the same results which led me to my conclusion of Mayor Jim Fouts being a probable match to the voice in question.
