Imagine for a moment that you’re sitting at home after a long day at work, enjoying some time in your living room, watching TV or the like. All of a sudden, you hear the door open behind you. You sit and wonder who could have walked in, until the anonymous person speaks. The second you hear their voice, you recognize and register immediately who has entered the room. The same scenario can happen all day at work as well. You learn to recognize your co-workers voices after hearing them all day for several months, even years.
As these examples show, we recognize and interpret characteristics of voices very quickly. Why is this? Vocal characteristics are very distinct amongst all people regardless of race, gender, or ethnic background. If you spend a decent amount of time around someone, you become used to the vocal characteristics they express and can immediately correlate those characteristics with the identity of who is speaking to you.
Vocal Identification in audio forensics relies on the ability to recognize these characteristics in any unknown human voice. In the examples above, the repetition of exposure to those vocal characteristics make you respond without even thinking twice about who could be behind you. The difference in regards to audio forensics is that a forensic expert doesn’t always know anything about the voice in question. This requires the forensic expert to rely on their ‘critical listening skills.’
So, how is this done? What specific characteristics are forensic experts actually looking for? They look for the types of speaking characteristics that could be relevant and specific in identifying a person’s voice. Everyone has very distinct features to their voices, regardless of how slight or severe they might be. When compiling information for voice identification, the forensic expert must listen over and over to the unknown voice with pen and paper taking scrupulous notes of all speech characteristics. They focus specifically on things such as inflection, pronunciation of certain words, any form of an accent, stutters and lisps, amongst other variables. Make careful and precise notes about all of these variables. They try to be as SPECIFIC as possible. The forensic expert will then create a voice profile for this person.
If by chance the forensic expert has access to the suspect thought to be the unknown voice, this puts them at more of an advantage. The goal then is to create an exemplar of that person saying the same message in question with the same delivery heard in the recording. This is called an ‘exact exemplar.’ They will review and compare notes from both the original recording and the exemplar itself. An exemplar gives you a more neutral quality, and isn’t biased by background noise, feedback, or any other external features that may have affected the original recording.
By understanding the critical listening phase of voice identification, you will better understand the value and importance of voice identification as a tool for the audio forensic examiner and audio forensic expert.
For more on Voice Identification, check out Ed Primeau’s latest book, “That’s Not My Voice!” available on Amazon.
Tags: voice identification