# Numerical Modeling of Bowel Sound Propagation: Impact of Abdominal Tissue Properties
## 1 Introduction  
Bowel sounds, including rumbles, grunts, trebles, and growls, are typically produced by the movement of liquids, food, digestive juices, and air in the intestinal tract [1]. These sounds are primarily produced by the rhythmic contractions of the intestines, a process known as peristalsis. They are affected by the mechanical interactions between the digestive contents and the walls of the intestines [2]. Analyzing the presence, frequency, and intensity of these sounds provides valuable diagnostic insights into gastrointestinal diseases, particularly in their early detection. For instance, [PERSON] et al. [3] demonstrated that bowel sound analysis accurately diagnoses small amounts of ascites. [PERSON] et al. [4] utilized two-dimensional localization techniques to differentiate between irritable bowel syndrome (IBS) and [PERSON]'s disease, pioneering a new approach in the classification of functional bowel disorders. Moreover, [PERSON] et al. [5] found that bowel sounds had a positive predictive value of 72.7% for diagnosing acute intestinal obstruction, highlighting their potential in rapid screening. These findings underscore the significant clinical applications of bowel sound analysis, particularly in the early identification of gastrointestinal conditions, though further efforts to standardize and objectify the method remain essential. Bowel sound analysis has shown significant potential in diagnosing various gastrointestinal diseases and has made progress in theoretical research. However, its clinicalapplication remains challenging. Currently, interpreting bowel sounds is heavily dependent on the clinician's experience and is susceptible to interference from environmental noise and individual variability, limiting its standardized use in clinical settings. Furthermore, while conventional stethoscopes are commonly employed for bowel sound assessment, they remain subjective and fail to provide objective, standardized results [6]. The complex nature of bowel sounds, characterized by variations in frequency, intensity, and duration, presents challenges for automated detection [7] and analysis [8] techniques in achieving the accuracy needed for clinical applications. Existing automated methods often struggle to provide consistent and reliable diagnostic information when confronted with diverse disease states and individual differences. Moreover, the absence of large-scale, standardized bowel sound databases and uniform classification criteria further limits the widespread application and effectiveness of these techniques across various diseases. Most existing studies have focused on methods and devices for acquiring bowel sounds [9; 10; 11], with relatively little attention given to bowel sound simulation. The development of bowel sound simulation devices is of significant importance, as they provide objective and controllable samples that can improve the accuracy and reliability of automated analysis techniques. This advancement may also support the establishment of standardized classification and diagnostic frameworks. Additionally, such devices can contribute to the creation of large-scale, standardized bowel sound databases, promoting the widespread application of bowel sound analysis across various clinical conditions. [PERSON] et al. [12] developed a mathematical model of bowel sound generation, simplifying the vibration of the intestinal wall into a spring-mass-damping system. Their study primarily focused on the mechanisms of sound generation within the intestine [13]. However, existing research has limited insight into the propagation of bowel sounds within the abdominal cavity [14]. The physical properties of various tissue layers, including thickness, density, elasticity, and impedance, heavily influence the propagation characteristics of bowel sounds [15]. Individual differences, particularly in fat layer thickness, can lead to significant attenuation and distortion of bowel sounds as they travel through the abdomen [16; 17].