This study investigates the influence of ambient temperature on the energy conversion performance of a thermoacoustic engine (TAE) operating with air at atmospheric pressure. A looped-tube TAE model was developed and analyzed using finite element simulations. The primary parameter of interest was the ambient (cold-side) temperature, which was varied systematically to represent cold (−18°C), moderate (28°C), and hot (45°C) environmental conditions, and to evaluate its impact on onset conditions, acoustic power generation, and overall efficiency. Results show that smaller flow channel radii, particularly 0.27 mm, yields the highest performance across all ambient temperature scenarios due to enhanced acoustic impedance and pressure amplification. At this radius, both exergy and energy efficiency are the highest under hot ambient conditions, reaching 61 % and 23%, respectively, although the system requires higher hot-side temperatures for operation. These findings highlight the importance of optimizing flow channel geometry for efficient thermal-to-acoustic energy conversion under realistic environmental conditions. The study provides a foundation for designing TAEs adaptable to diverse climates and practical waste-heat recovery applications.