It is very important for audio forensic experts to develop their critical listening skills over time. Critical listening skills are extremely important for voice identification. Headphones and studio quality speakers will aid in critical listening skill development and investigation of spoken word recordings. The tone and pattern of voice vibrations vary from person to person and can be more audible using headphones for some testing procedures and studio speakers for others.
Headphones are used to prevent outside disturbance and enhance an audio forensic expert’s critical listening focus, whereas studio speakers provide another perspective and are easier to work with and adjust to. Headphones can also provide a level of sound fidelity different from and more accurate than loudspeakers. Studio speakers use the listening environment (room acoustics) to aid in critical listening and to make it easier to quickly move through voice files. Headphones may slow down an expert’s work, but may also add to their listening focus. In other words, headphones may be a bit clunky and harder to get used to, but they can help an expert hear sounds that loudspeakers will produce differently because of room acoustics.
Whether audio forensic experts are using headphones or studio speakers, they need to abide by some standards. When comparing spoken word samples for the purpose of identification, experts must base their processes on information learned and accepted in the scientific community, in state police crime labs, by other forensic experts, and by the designers and developers of electronic equipment (especially computer equipment) and testing software programs. The process requires visual, electronic, and auditory examination of every aspect of the words spoken. The examiner must use and apply critical listening skills not only to the words themselves, but also to the way the words flow together, the pauses between the words, and the way the words are formed by the mouth and larynx of the person speaking. Speakers and headphones can aid them in this process.