<p>Acoustic noise has recently become an issue in printed circuit boards (PCBs) equipped with multilayer ceramic capacitors (MLCCs). This is because the piezoelectric properties of the dielectric material within the MLCCs cause vibrations due to the applied electric signal, which are transmitted to the PCB and cause resonance of the PCB, resulting in undesirable acoustic noise. This issue is particularly critical as electronic devices increasingly require quieter operation, such as in fanless laptops and smartphones. This study proposes a novel, cost-effective method to reduce PCB noise caused by MLCC vibrations using additional elastic supports, without modifying the PCB design or employing expensive low-noise MLCCs. The force acting on the PCB due to MLCC vibration was calculated by the blocked forces of the MLCC, and the change in the mobility matrix of the PCB due to additional elastic supports was calculated through frequency response function-based substructuring. By optimizing the number and location of additional elastic supports, the proposed method effectively reduces acoustic noise while preserving the original PCB structure. The proposed method was validated through finite element analysis, demonstrating its effectiveness in minimizing acoustic noise across different support configurations. This study provides a practical solution for reducing noise in PCBs without compromising their electrical performance.</p>