###### Abstract  
Emotional communication is a multi-modal phenomenon involving posture, gestures, facial expressions, and the human voice. Affective states systematically modulate the acoustic signals produced during speech production through the laryngeal muscles via the central nervous system, transforming the acoustic signal into a means of affective transmission. Additionally, a substantial body of research in sonobiology has shown that audible acoustic waves (AAW) can affect cellular dynamics. This pilot study explores whether the physical-acoustic changes induced by gratitude states in human speech could influence cell proliferation and Kief7 expression in non-auditory cells (661W cell line). We conduct a series of assays, including affective electroencephalogram (EEG) measurements, an affective text quantification algorithm, and a passive vibro-acoustic treatment (PVT), to control the CO\({}_{2}\) incubator environment acoustically, and a proliferation assay with immunolabeling to quantify cell dynamics. Although a larger sample size is needed, the hypothesis that emotions can act as biophysical agents remains a plausible possibility, and feasible physical and biological pathways are discussed. In summary, studying the impact of gratitude AAW on cell biology represents an unexplored research area with the potential to enhance our understanding of the interaction between human cognition and biology through physics principles.  
emotions; human voice; gratitude; cell proliferation; protein expression; mechanotransduction; sonobiology +
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that humans can perceive and differentiate the emotions of others by listening to voice signals [20; 21; 22; 23; 24].  
One emotion that falls within the positive emotion category is gratitude. Consider the affective feeling of having a flat tire on a remote road and a passerby stops to assist you in changing it. Such unexpected acts of kindness can evoke strong feelings of gratitude, emphasizing the importance of social support in times of need. Gratitude is strongly associated with higher well-being, social relationship benefits, and lower stress and depression levels [25; 26]. Several studies have revealed that gratitude correlates with areas of the anterior cingulate cortex (ACC) and medial prefrontal cortex (mPFC) [27; 28]. Electroencephalogram (EEG) devices have demonstrated their potential for classifying positive emotions, including gratitude, with an accuracy of approximately 80% [29]. Likewise, the use of gratitude letters has been demonstrated to be an effective method for inducing feelings of gratitude in laboratory settings [30; 31], and affective dictionaries have been proposed as a systematic method for assessing and quantifying the emotional content of textual data [32; 33].  
Additionally, several studies have demonstrated the capacity of audible acoustic waves (AAW) to alter cell behavior [34; 35]. The well-established field of mechanotransduction examines the physical-biological process by which AAWs reach the extracellular matrix and interact with cell nuclei [36; 37; 38]. Building on this idea and the concept that emotions act as physical modulators of human speech, we hypothesize that gratitude AAWs could influence cellular dynamics through the human voice. Specifically, this pilot study aims to determine whether gratitude, as a biophysical agent, can affect the proliferation of non-auditory cells.