Neurovegetative and Emotional Modulation Induced by Mozart’s Music

Introduction

Music is a ubiquitous component of human life, so that the “power” of music is perceived and experienced by human being, more or less consciously, in almost every moment of their life, since we constantly live immersed in sounds. Several studies investigated the potential of music and sounds on human cognition and social capabilities (e.g., [1]). In the last decades, the idea that music can be used for therapeutic purposes led to the birth of a new discipline: music therapy [2]. According to the psychiatrist and musician Rolando Omar Benenzon, music therapy is a psychotherapy technique in which sound, music, and musical instruments are used to foster a process of connection between the therapist and the patient or the patients’ group, with the aim of improving the quality of life and rehabilitating and recovering patients’ footing in society [3]. As a matter of fact, the discipline of music therapy has been developed since antiquity [4].

William James defined our “susceptibility to music” [5]: music affects the human being relaxing, animating, comforting, exciting, and also representing a therapeutic potential in patients with different neurological conditions (e.g., [6^-8]). Music has always been associated with the treatment of mental illness, given the potential of music in reducing anxiety, stress, tension, and pain (e.g., [9^-13]). However, most studies only refer to self-reported information provided by the patients; therefore, potential associations between subjective and objective parameters – such as physiological values – remain to be deeply evaluated to show more reliable results and foster the use of music as a standardized method of intervention for anxiety and pain relief.

Over the years, various sound- and music-based treatments have been developed with different purposes (from relaxation to performance improvement, up to more complex therapeutic objectives). Examples of techniques are psychophony (sound is used as a direct factor of intervention), sound therapy (the diapason is used to stimulate certain points of the body), sound massage (an instrument is held close to various body areas to “massage” the body), and therapeutic listening (personal listening of classical music). Concerning the latter, a specific enhancement of cognitive skills has been described and it has been defined as the “Mozart effect” [14^, 15].

The “Mozart Effect”

A study that appeared in 1993 described how listening to the Sonata for two pianos in W. A. Mozart’s D Major K 448 induced an improvement in cognitive learning [15]. Authors suggested that Mozart’s music helps organize neuronal circuits of the cerebral cortex (mainly the organization of firing pattern of the right hemisphere processes of spatiotemporal tasks performance) and strengthen the creative processes of the right hemisphere of the brain, predominantly associated with spatial abilities. Since then, the enhancement of cognitive performance induced by music exposition is known as the “Mozart effect.” This finding sparked a series of studies that investigated the cognitive effects of classical music more specifically. For a detailed description of these studies, see Figure 1 [8^, 16^-24]. All in all, the findings provide compelling evidence to previous experiments that the Mozart effect can be an artifact of arousal and mood [18^, 25^, 26].

Open multimedia modal

Psychophysiology and Music

Generally, musical stimuli and sound stimuli can arouse organic and psychological manifestations of the dynamic functions of the human being [3]. Music cannot be separated from perceptual, symbolic, and personal processes [27]. Indeed, music can stimulate central emotions in the brain and release biochemical signals that change the physiological state [28], as revealed, e.g., by heart rate (HR), blood pressure, and skin conductance. Several cardiac and neurological functions, as well as biochemical measurable effects, are triggered by different kinds of music [29]. For example, sedative and arousal music, compared to the silence condition, influenced the electrical function of the heart with a transitory effect on heartbeat and electrocardiographic signals [30]. Fried [31] pointed out those factors affecting the relationship between the autonomic nervous reactions and music, such as age, sex, life-style, physical fitness, health, temporary states induced by alcohol, coffee, emotional factors, attitudes toward music and its role in one’s life, and attitude toward the musical selection. McClellan [32] identified some features of pancultural music that seemed to be useful to calm and reduce tension, such as the rhythm of the music. Beyond heartbeat, HR variability (HRV) is related to neurocardiac function and is generated by heart-brain interactions and processes of the dynamic nonlinear autonomic nervous system (ANS) [33]. For details, see Figure 2 [33^-40].

Open multimedia modal

In addition to heartbeat system, some authors focused on breath as a response system and in the context of relaxation and stress techniques [41]. Indeed, some forms of music have been reliably shown to have a profound beneficial effect on breathing [31]. Abnormal respiratory rate (greater than 20 breaths per minute) indicates physical discomfort and can be an important predictor of serious clinical events [42^, 43]. Koelsch and Jäncke [44] summarized the effect of music on cardiorespiratory system, pointing out that music reduces HRV (in particular exciting music) and increases heart and respiratory rate (in particular exciting and/or pleasant music).

Materials and Methods

Results

Participants were overall not affected by excessive values of general distress, anxiety, depression, and stress, as resulted from the DASS-21 data (see Table 1) compared to the data reported in previous studies [49]. As well, breathing rate [43] and SpO₂ were overall in a normal range. Among the four dimensions of the ITAMS questionnaire taken into account, anger, tension, and vigor were significantly reduced after Control condition, whereas no significance nor tendency was found after Destructured listening about the reduction of fatigue and tension, and a strong tendency emerged for the reduction of vigor. After Mozart listening, fatigue was significantly reduced (and a tendency emerged also for tension), whereas vigor was not affected (see Table 2).

Open multimedia modal

Open multimedia modal

Comparing the measures acquired during each condition, no significant differences emerged for SpO₂ (χ²₍₂₎ = 3.11, p = 0.212) and breathing flow (χ²₍₂₎ = 1.95, p = 0.378). Although almost statistically trivial, a difference emerged for breathing rate, which was higher during Mozart listening than in the other conditions (χ²₍₂₎ = 4.15, p = 0.126, η²_p = 0.09). HR did not change by listening condition (F_{2, 34} = 0.66, p = 0.524), as well as the HRV metrics of SDNN (F_{2, 32} = 1.63, p = 0.218) and pNN50 (χ²₍₂₎ = 2.73, p = 0.255). Among nonlinear metrics derived from Poincaré plots, nonsignificant differences were found for both SD1 (F_{2, 34} = 2.56, p = 0.092, η²_p = 0.13) and SD2 (F_{2, 34} = 2.16, p = 0.130, η²_p = 0.11) with lower values during Mozart listening; instead, neither CSI (F_{2, 34} = 1.67, p = 0.204) nor CVI (F_{2, 34} = 1.11, p = 0.331) did change across conditions. LF/HF did not significantly change, (χ²₍₂₎ = 1.00, p = 0.607). The nonlinear parameter HFD, even though not significantly, was slightly lower during Destructured listening (F_{2, 34} = 2.54, p = 0.117, η²_p = 0.13) (see Table 3).

Open multimedia modal

Partial correlations (see Table 4) revealed that in Control condition fatigue change was significantly associated with HR (rho = −0.552 and p = 0.021), and tendencies were found for fatigue change with breathing flow (rho = 0.400 and p = 0.059) and for tension change with HFD (rho = −0.372 and p = 0.073); controlling for general distress, the association of fatigue change with HR was mitigated (rho = −0.449 and p = 0.036), while the association of tension change with HFD was exacerbated (rho = −0.472 and p = 0.023). In Destructured condition, significant associations were found for anger change with HR (rho = 0.524 and p = 0.021) and for fatigue change with breathing flow (rho = −0.486 and p = 0.048) and tendencies for fatigue change with breathing rate (rho = −0.417 and p = 0.096) and for vigor with HR (rho = 0.449 and p = 0.054); after controlling for general distress, only trivial differences occurred. In Mozart condition, only a tendency in the association of vigor change with LF/HF was found (rho = 0.406 and p = 0.061); after controlling for general distress, only trivial differences occurred.

Open multimedia modal

Discussion

The results of our study show that listening to Mozart did not empower the relaxation – neither subjective nor objective – in healthy young adults. In other words, Mozart’s Sonata in A major K 331 did not empower a contextual set which per se produces relaxation.

It was advocated to better define the influence of sound, noise, and music on psychological and physiological variables [55]. In our study, listening to the beat or silence reduced the vigor subscale, whereas listening to Mozart’s Sonata did not. We did not find any significant difference for SpO₂, HR, SDNN, PNN50, CSI, CVI, LF/HF across the conditions but tendencies for SD1 and SD2 – with lower values listening to Mozart’s Sonata – and for HFD, with higher values during control. Breathing volume did not differ across conditions, and a tendency was found for breath frequency, with higher values when listening to Mozart. Almost surprisingly, we may affirm that Control was the most relaxing condition, and Mozart’s Sonata slightly supported arousal most of all. Orini and colleagues [56] also reported silence to be the most relaxing condition assessing a panel of heart, breath, and HRV metrics to depict the changes while listening to pleasant or unpleasant music, compared to silence.

The musical components more conducive to relaxation (considered in terms of relaxing music for anxiety control and not relaxing music for any purpose), in descending order, can be listed as follows: tempo, melody, beat, harmony, rhythm, liking, complexity, key, scale, articulation, interval, melodic range, and familiarity [46]. Slow attacks, low rhythmic complexity, and low dynamic range define relaxing music [57]. The physiological relaxed state may be triggered by music with slow tempo, mellow timbre, and soft volume [58]. The most used piece for investigating the Mozart effect is Sonata K448, made up of three tempos, all in a major key: Allegro con spirito (D major), Andante (G major), and Allegro molto (D major). The first and third tempo are part of the “fast tempo” group (about 84–168 bpm), the second beat slows down for a while (Andante); the sensation that the piece arouses in the listener is of joy and cheer. The piece used for this study, extracted from Sonata K 331, has a moderately slow tempo and a lulling rhythmic and melodic trend and arouses calm; therefore, its characteristics, despite several musical variations, are more prone to a relaxing piece than K 448. Nonetheless, it produces a positive effect on mood, maintaining arousal compared to only beat or silence.

Considering the psychophysiological association, we argue that there was not a necessary entanglement between psychological effects and physiological dynamics of cardiovascular system. This is in line with other findings, such as those of Hernandez-Ruiz ad colleagues [58], although they considered only the end of listening; they also argued that the profile of responders versus nonresponders may drive the results. The reasons for what physiological measures do not necessarily parallel psychological responses may lie on conscious interpretations of emotion, on the nondichotomous response of arousal or relaxation, and on the plethora of metrics of interest. The variations in mood variables in response to listening conditions are only partially associated with physiological features; those with higher HR encountered a higher reduction in fatigue, but only in Control condition, partially mitigated when controlling for general distress. This makes sense as fatigue change and general distress were negatively correlated (rho = −0.526, p = 0.008), i.e., the more stressed you are, the more you benefit of a relaxing condition. This was also revealed by the negative association of HFD with tension change, i.e., the reduction in tension was underlain by higher fluctuations of heart rhythm. In Destructured condition, the greater the reduction in fatigue, the more relaxed the breath, and the higher the HR, the lesser the reduction of anger and vigor. In Mozart condition, the higher the LF/HF ratio, the lesser the reduction of vigor. Therefore, each condition was underlain by meaningful, but unique, psychophysiological signatures. Id est, each condition was defined by a specific psychophysiological associative signature, possibly resulted from a different involvement of autonomic pathways.

As a limit of this study, it would have been helpful to contrast two or more different pieces of music balanced for emotionality on the basis of tempo and melody; the duration of the musical stimulus, lower than most of similar studies, limits the comparison of current findings with literature evidence. It would have been helpful to compare the psychophysiological response with personality, empathy, music preference, anthropometric variables, and basal status of ANS. For example, introverts can benefit from fast-tempo music for tasks requiring greater mental effort, while extroverts contrarily can predispose themselves to excessive risks [59]. Similar responder profile differences may lead to several psychophysiological outcomes when listening in relaxing conditions. Sensitivity to music features vary whether listeners are trained musicians [47]; although we assessed the level of musical competence, the percentage of volunteers with advanced competence (conservatory or other advanced musical courses attended) was too low for using this variable for statistics. Even though HRV complex metrics represent an intriguing hallmark of stress, disease, and aging, caveats should be highlighted about the use of HRV diverse metrics for feasible applications, as large misuse and overuse flaw such indexes.

Conclusions

Considering the potential of music in affecting neuropsychological and behavioral variables, we suggest that an individual approach to music should drive the music as medicine [4]. A very interesting example concerns the genetic regressive sounds, causing greater regressive effects in the human being than any other sound, more or less constant and above all independently of the pathology or individual characters. One of these sounds is the heartbeat [3]: infants exposed for 4 days to a heartbeat-like noise cried less and gained more weight than the control group; newborns in the womb undergo an auditory imprinting of the mother’s heartbeat probably causing cascading associative learning mechanisms lasting beyond early life [60]. More generally, this finding adds important evidence in the dynamic frame of the nature versus nurture preference for sounds and music (e.g., [61]). It would be interesting to furtherly investigate whether and how the psychophysiological effect induced by auditory stimulation could refer to its similarity to “biological musicality.” In this regard, sound identity (ISO) refers to the set of sounds that characterizes each human being [14]. As Benenzon argues, music therapy acts through our ISO, which is represented by sound, acoustic, and movement energies [3^, 62]. The ISO approach may represent a music-based application of the personalized therapy model, which accounts for an ad personam modeling of dynamic processes and aims to increase both rapidity and effectiveness of psychopathological therapies [63]. The analysis of sonogram and spectrograms linked to individual features, as already proposed for psycholinguistic structures [21], may unveil novel insights within this framework. All in all, further efforts are needed to extend the insights on the complex link between music and psychology, considering the effect of music on behavioral responses and personality traits [64].

We have argued that listening to Mozart’s music may stimulate arousal even during relaxing conditions. Objective and subjective measures of relaxation represent a complex set of variables, not necessarily entangled. Finally, we advocated for further ad personam musical pieces, basing on physiological individual signature, to produce tailored musical psychotherapy.

Statement of Ethics

The research was conducted ethically in accordance with the World Medical Association Declaration of Helsinki and followed the ARRIVE guidelines. Ethics approval was not required in accordance with national guidelines as reported in the Italian Ministry of Health circular n. 6, 2002, and the Italian Legislative Decree n. 211/2003, which define interventional and noninterventional trials that are subjected to the ethical approval; this study does not involve patients, children, or animals, as well as drugs, genetic samples, or invasive techniques. Written informed consent to participate in the study was obtained from all the participants after a full explanation of the procedures.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

This research was supported by the “Departments of Excellence 2018–2022” initiative of the Italian Ministry of Education, University and Research for the Department of Neuroscience, Imaging and Clinical Sciences (DNISC) of the University of Chieti-Pescara.

Author Contributions

Conceptualization: Margherita Di Cesare, Danilo Bondi, and Tiziana Pietrangelo; methodology: Margherita Di Cesare, Alessandro Tonacci, and Danilo Bondi; formal analysis: Alessandro Tonacci and Danilo Bondi; investigation: Margherita Di Cesare and Danilo Bondi; writing – original draft: Margherita Di Cesare, Alessandro Tonacci, Danilo Bondi, Giulia Prete, and Gianluca Malatesta; writing – review and editing: Margherita Di Cesare, Alessandro Tonacci, Danilo Bondi, Vittore Verratti, Giulia Prete, Gianluca Malatesta, and Tiziana Pietrangelo; funding acquisition: Tiziana Pietrangelo; resources: Alessandro Tonacci, Danilo Bondi, Vittore Verratti, and Tiziana Pietrangelo; and supervision: Vittore Verratti and Tiziana Pietrangelo.

Data Availability Statement

The data that support the findings of this study are not publicly available, as the key point of the procedure (the musical stimuli) is not owned by the authors, but are available, along with physiological time series and psychological results, from the corresponding author DB upon reasonable request.