Accurate material characterization over time is crucial for the safety, efficiency, and sustainability of energy and environmental projects, as well as infrastructure resilience. This is particularly important in nuclear power plants and energy geo-structures. The Bender Element (BE) test is a non-destructive technique (NDT) used to assess small-strain properties of materials, including Shear Wave Velocity (Vs) and Shear Modulus (Gmax). BEs, made of piezoelectric materials, operate by applying an excitation voltage to a transmitter (Tx), generating shear waves that propagate through a specimen and are detected by a receiver (Rx). Small-strain properties are determined from the computed Vs. Despite standardized guidelines (e.g., ASTM D8295-19) and widespread BE applications in soil characterization, challenges persist in implementation and data interpretation. A major issue is the accurate determination of S-wave arrival time, often complicated by interference from P-waves and reflected waves, leading to measurement inaccuracies. A key knowledge gap exists in understanding BE interactions with different materials under varying confinement stresses. This research evaluates BE behavior under diverse conditions, proposing alternative methods to verify Vs measurements. The study comprises three phases: experimental testing, numerical modeling, and theoretical equation evaluation. BE lab tests were conducted using transparent soil under varying confinement stress, incorporating laser vibrometry to measure displacements on BE plates despite surrounding soil. Signal responses were analyzed in both time and frequency domains. Numerical modeling employs a novel finite difference simulation in FLAC3D (Itasca 2023), calibrated with experimental results. Additionally, the standard equation for BE resonant frequency prediction was assessed, considering confinement effects on system stiffness. The Hilbert Transform was applied to evaluate instantaneous frequency responses. The proposed method introduces new approaches for selecting S-wave arrival time, incorporating BE resonant frequency and time-domain frequency analysis. These findings enhance understanding of BE-sample interactions, improving the interpretation of BE test results.