The Use of Forensic Musicology in Criminal Investigations

Review Article

Austin J Forensic Sci Criminol. 2023; 10(1): 1095.

The Use of Forensic Musicology in Criminal Investigations

Zaroon; Jumana Rashid; Anwaar Iftikhar; Hamid Bashir; Rukhsana Parveen*

CAMB, University of the Punjab, Lahore, Pakistan

*Corresponding author: Rukhsana Parveen CAMB, University of the Punjab, Lahore, Pakistan. Email: [email protected]

Received: May 23, 2023 Accepted: June 20, 2023 Published: June 27, 2023

Abstract

Forensic musicology is the scientific study of music in a legal context. It can be used to help identify the composer of a piece of music, to determine the ownership of a copyright, or to resolve disputes over the use of musical works. Forensic musicologists may also be called upon to give expert testimony in court cases involving questions of music.

Forensic musicology is a relatively new field, and there are no formal educations or training requirements for becoming a forensic musicologist. However, most forensic musicologists have advanced degrees in music theory, musicology, or a related field, and many also have experience working as professional musicians. Forensic musicologists use their knowledge of musical composition, history, and performance to answer questions raised in legal cases.

Forensic musicologists typically collaborate with attorneys, judges, and other legal professionals to provide expert testimony or analysis in court cases. In some cases, they may also be asked to testify in front of a grand jury or give depositions. Forensic musicologists may also be consulted by law enforcement agencies to help identify unknown pieces of music or to authenticate recordings. This review will focus on the application of forensic musicology in civil and criminal cases.

Keywords: Forensic; Forensic musicology; Music; Legal

Introduction

Forensic musicology gained significant popularity as a discipline in the late years of the twentieth century [1]. There are many potential applications of forensic musicology used in different fields today. Many countries around the world are currently demonstrating a deep extent of utilizing voice analysis. This trend is especially far more noticeable in developed countries [2]. The significance of voice recognition and analysis cannot be undermined as they play a pivotal role in solving so many criminal cases every year [3]. Criminology aside, forensic musicology has played a critical part in infringement cases involving the music industry [4].

Forensic musicologists have been called to courthouses over many decades to check the similarities between two pieces of music. These connoisseurs analyze the similarities between the music pieces and give a verdict on whether the two music pieces are similar or not. In cases with substantial evidence of similarity or infringement, these forensic musicologists have to testify in open court as well. This practice came to be in use fairly recently. The practice before was nowhere near this professional. Forensic musicologists create legal evidence that is based on logic and reason. The evidence that these experts can create holds a visual significance. This might be one of the many reasons why courts in different countries have started viewing different music samples as violations of copyright [5,6].

A term that is currently being used frequently in copyright laws is ‘reverse engineering’. This term refers to the use of previous work done in the early years and presenting that work or a form of it in the recent version. More efficient legal regulations are being put into place regarding this how to cover this aspect of copyright laws with forensic musicology. Forensic musicology is a study that evolves every day. New techniques are being tested and applied to increase the effectiveness and efficiency of the system and the results that are produced as a result of forensic musicology [7]. Since forensic musicology is playing its role for almost two hundred years the disciples of forensic musicology has only been recognized consistently since the late 20th century. Recent emergence of it has contributed to the dearth of academic study on its method, history and important figures.

Importance of Forensic Musicology

The ongoing transition of the music business to digital recording and distribution has enhanced the expertise that legal professionals need from specialists. A wide range of legal concerns, including the identification and authentication of published works and musical recordings, performance rights, and legal rulings involving copyright infringement are supported by expert testimony for forensic musicology. Even though there have been legal instances concerning music and performance infringement since the 19th century, there is no established approach in the field of forensic musicology that allows for an objective forensic assessment [8].

To understand and realize the importance of forensic musicology, a basic understanding of the working of voices and sound is mandatory. This understanding will further lead to understanding the frequency, and pitch of the sound, and finally, getting to know the complex processes such as Automatic Speaker Recognition (ASR), forensic voice comparisons, and so on. Vibrations in the atmosphere produce the sound that we hear, and the frequency of a sound is a measure of how fast +or slow it makes the air vibrate around it [1].

For two voices to belong to the same person, there should be considerable similarities between the two. Otherwise, the alternative is that the voices belong to different people if they do not share similarities. Apart from the similarities, the voice should be clearly and categorically distinct in nature. The complexity of the human voice makes it extremely difficult to pinpoint one voice to one person based on similarities and distinctiveness. The same person may sound different in a cold or any other health issue that affects the voice [9].

Forensic musicology has been used to distinguish between the different music types in countries such as Africa where there is an amalgam of so many cultures with different traditions and music types. By use of forensic musicology, experts have been able to clearly define the boundaries and have been able to distinguish between the many types of music in different cultures of Africa. Forensic musicology therefore is helping in the detection of following areas in music [10].

Voice Recognition

Voices and faces both contain intricate stimuli that provide vital social information. Both play a role in the recognition and differentiation of certain individuals. These parallels raise the possibility that speech recognition technology may have evolved similarly to facial recognition technology in certain ways [11].

Voice Recognition is the ability of a machine how well it perceives a spoken command by a person and how the machine interprets this information. This technology has been utilized by some of the biggest tech industries of today, such as Amazon, Microsoft, and Apple. These companies have applied the technique of voice recognition and made custom software for their tech devices. For instance, Apple has made Siri, Amazon has Alexa and Microsoft has Cortana. Recent years have seen a significant convergence between the methods and techniques used to develop man-machine interaction based on the word and the data statistical modelling paradigm (such as HMM-based acoustic modelling, n-gram-based language modelling, and concatenative speech synthesis). Of course, over the course of nearly three decades, these techniques have actually improved the quality and performance of the system, leading to this convergence of modelling paradigms [12].

For a computer to recognize anything, the signal has to be digital in nature. In that regard, the audio is initially converted to a digital form by a process known as analog to digital conversion. These conversions of speech patterns are stored in the computer on the hard drive. Pattern recognition is used by a comparator to check these speech patterns [13].

The acoustic characteristics of voice also reveal a speaker's identity in addition to their views and intents. The ability to identify people from their sounds has been studied in lab settings. Voice recognition, however, includes two components: (1) the ability to identify the voice of a known individual, and (2) the ability to familiarize a voice, that is, to encode a voice and retain some feature of it in long-term memory [14].

Automatic Speaker Recognition is an application of forensic musicology with immense scope and significance in not only an investigative approach but also the reporting of evidence. When we take an example of a case that is normally encountered by law enforcement officials on a routine basis, one such where a victim has received a call of a threatening nature [15]. In this scenario, a suspect list is made by comparing the voice on the call with that of the criminals. This sample voice on the call is called the trace [16]. Automated speaker-recognition systems have become a crucial tool for identity verification in many e-commerce applications, as well as in everyday commercial encounters, forensics, and law enforcement [17]. By analyzing a variety of acoustic, prosodic, and grammatical aspects of speech in a method known as structured listening, human professionals skilled in forensic speaker recognition may execute this task even better. Forensic speech scientists and linguists have been working on techniques for forensic speaker recognition for many years in an effort to help eliminate any prejudice or previous notions about the reliability of an unknown audio sample and a reference template from a suspected suspect [18].

Forensic voice comparisons come in handy in criminal cases where physical evidence is absent or sufficiently minimal. In case of a ransom call from a hostage situation where there is no physical evidence such as DNA or fingerprints to go on, the only lead available is the voice of the caller. By running this trace with the database of voices present, there is the formation of a list of potential suspects. Further analysis of this sample recording can yield even a single entity where it is highly likely that the caller and suspect are one and the same person [19].

Study of Tampered and Original Sounds

Before 1950s and even in some cases now sounds and voices are analyzed by experts known as linguists. These professionals are trained in linguistics, which is the scientific study of speech as well as language. This type of voice analysis is called linguistic analysis. This field has been upgraded and different linguistic features are examined and compared in this study by the experts. The whole sample speech or trace is broken down into chunks. These separate chunks are carefully listened to by linguists. This part of the analysis is known as the auditory analysis since it deals with specific sounds.

Copy-move, deletion, insertion, substitution, and splicing are all methods of faking audio. As copy-move forgery entails shifting a portion of the audio to another point inside the same stream, its applicability are constrained in comparison to other methods. On the other side, integrating recordings from various speakers, devices, and surroundings may be involved in the deletion, insertion, replacement, and splicing of forged audio [20]. Different systems have been suggested to study the tampered verses original sound such as one suggested system's main goal is to resolve the following problems with high accuracy and a high categorization rate:

1. Determine the difference between authentic audio and audio that has been altered by combining recordings made using the same microphone in various settings.

2. Environment categorization of authentic and fake audio produced via splicing. Regardless of speaker or content (i.e., text), detect counterfeit audio.

3. Reliable authentication using briefly fabricated audio [21].

Studying sound and making a comparison using these different developed software and tools have helped courts to study cases with legal and visual evidence [22]. This could help a judge to see how songs look onto a paper that he could clearly differentiate between original and tempered sounds [23].

Music as a Weapon

Acoustic weapons have been developed since the end of the past century as part of a non-lethal weapon invention. According to theories put forward by many experts over the years, the effect sound has on the body and its functions have been focused majorly. Sound and music have also been linked as a means of eradicating the subjectivity of a person during interrogation. Every article in the US press that has been linked to the use of music to torture prisoners or detainees has culminated in a reaction from the virtual side as well in the platform known as the blogosphere [24]. The Joint Non-Lethal Weapons Task Force's founding in 1997 in US is working for the Department of Defense have been developing "acoustic weapons," which accounted for a third of the Task Force's budget from 1998 to 1999. Whereas theorists of the interrogation chamber concentrate on the ability of sound and music to destroy subjectivity, those of the battlefield place more emphasis on the physical impacts of sound [25].

In the Yugoslavian wars that took place in the 1990s, music was seen as a symbol of differences in ethnicities. It was seen as a means of violence. Experts have ruled that understanding music and the reaction and address of the public to this could have made sense of the ethnic conflict that rose during the wars. During the wars, music has been used as a weapon and means of torture in prison. It was used to invoke feelings of fear and anxiety in the prisoners by making it take the shape and form of a cleansing ritual. That being said, some ethnic groups also took strength from music and boosted their morale in the tough and challenging times of the wars [26]. In many ways, lower- and middle-class opinions and frustrations with people, things, and governments that exercise authority over the masses are fairly accurately reflected in popular music.

The second part of the 1960s saw groups headed by the young that fundamentally contested preexisting forms of political and cultural authority. This was when the desire for social change and the challenge to authority reached its highest degree of intensity. All this is reflected in the music of that era [27]. Popular music and social movements have a link that has not gotten as much attention as its significance merits. More research is critically required since, in addition to frequently lagging behind other disciplines in its attempts to comprehend the nature and significance of popular media, especially popular music and the different protest movements of 1960s [28].

Frequency-Based Testing for Identification of Distinct Types of Sound

There is a lot of information that can be gathered by the voice of a person. This voice can tell the origin, the birthplace of a person along with the area of the upbringing of that person. Different areas and people have different languages, accents, and dialects. Not surprisingly, the voice of a person is revealing about the heritage and culture as well. The differences in the shape and size of vocal cords along with the upbringing in how to use them cause people's voices to differ from each other [29].

Experts use spectrograms to analyze voices between people. Spectrograms are visual images of speech sounds that are made by specialized software. This process of analysis by looking at spectrograms is termed acoustic analysis. By looking at two spectrograms from different individuals saying the same word, there will be many differences seen in both, even though the word both of them said was the same [30].

If the spectrogram appears brighter, it can be deduced that there was more sound energy in terms of frequency at that particular time. An increase in sound energy will cause increased brightness to appear on the spectrogram. Spectrograms can reveal differences in how individuals from varying backgrounds speak the same words of a language. One person saying a word will not appear exactly as the spectrogram of another individual saying the same word. The human voice is far too complex, much like fingerprint and DNA [31].

There are variations in voice parameters and signals even in individuals of the same culture, and ethnicity. Children such as siblings share similar genetic markers and the same environmental parameters. Even in these conditions with so many similarities, they still will not share the same cadence of voice [32].

Some features that are part of a routine linguistic analysis include looking at the voice quality, pitch, and wording as well as grammar usage, timing, and rhythm of the voice. The level of fluency is also a parameter that is used by experts during their analysis. The vowels and consonant sounds made by a person are also looked at by experts. The accent of the speaker is also an important feature to look at.

Apart from the use of spectrograms, experts have other techniques to analyze voice samples as well. Audio pieces of evidence are not submitted as such in court hearings. Experts use two techniques to validate the authenticity of the audio clip as well as the message being delivered in it by two main categories of forensic multimedia. These include content authentication to confirm the contents of the sample. The other category used is noise reduction to deliver the message loud and clear and without any doubts about the perceived notions [33].

A court verdict holds tremendous value therefore, many techniques are applied to deliver the best evidence in terms of sound that is authentic in nature with minimal background noise [34].

Analysis Criteria in Forensic Musicology

Publishers and artists have traditionally turned to the legal system to seek compensation from someone they accuse of profiting from the theft of one of their original works. A forensic musicologist is typically called in to evaluate the pieces and provide testimony on their parallels and differences. Because of their capacity to transform unprocessed auditory data into admissible evidence, forensic musicologists have evolved into the knowledgeable listeners who decide how jurors of fact will testify both visually and aurally about the songs presented at trial. While hearing the similarities between two songs is a significant component of forensic musicologists' expertise, a significant portion of their job is visual in nature [35]. One of their main responsibilities is to take the songs' different components such as speed, rhythm, harmony, etc. and reduce them to their melodic "fingerprints." The musicologist must next convert the melodies into visually comparable, 'eye observed' notes on a scale. The forensic musicologist creates a "knowledge structure" through which the songs may be understood, experienced, and debated in addition to making them detectable [36]. Musicology analysis as like other forensic cases is performed by the field experts. These experts have the high knowledge regarding music. Since the music is so vast therefore the expertise are limited to a certain direction. Following are the major analysis performed by a forensic expert to solve or narrow down a certain case in music [37].