Forensic analysis of audio recordings isn't just a plot device in American TV series. Audio Experts perform similar tasks daily, although the real-world process differs significantly from the simplified depictions often seen on screen. A few button presses won't magically reveal hidden information or transform an audio recording into something entirely different. The truth is, forensic audio analysis is a complex process requiring specialized expertise. Gábor Balla, a forensic audio engineer, provides a brief overview of this field.
A well-written expert opinion should be comprehensible not only to the expert who authored it and other specialists in the field but also to the requesting authority. The summary of the opinion should be clear and concise, aiding the requester in understanding its implications. This principle guided us when we developed three methodological papers in the field of audio forensics. Our goal was to present our methodology, and especially the conclusions drawn from our examinations, in a manner that would be understandable to non-experts. The principles we employed can undoubtedly be applied in other fields where the integrity of an object submitted to an expert needs to be assessed.
The primary goal of audio enhancement is to reduce noise in recordings. Noise is present in all recordings, even those made in very quiet environments. Noise is caused by the physical properties of the recording equipment and the surroundings. In most cases, it's the ambient noise that needs to be reduced. If the recording is made on a busy street, in a car, or in a noisy place, the noise will drown out the desired speech. Other types of noise can include noise from electrical devices such as mobile phones, air conditioners, or transformers. In some cases, wind noise or noise from the recording equipment can also be a problem. Often, multiple types of noise occur simultaneously.