This report explores the synthetic recreation of natural sounds using modular synthesis, focusing on birdsong and insect sounds. The study investigates the realism of synthetic sound design and its potential use in audiovisual applications. Drawing on literature and practical analysis, spectrograms and frequency-time representations were employed to extract key sound parameters for synthesis. Using VCV Rack and iZotope RX as the primary tools, synthetic patches were created. Two surveys were conducted to evaluate the realism of the generated sounds compared to authentic recordings. Results indicate that while simpler sounds achieved convincing realism, complex birdsongs posed challenges due to limitations in texture and dynamics. Feedback emphasized the importance of variation and stochastic elements for authenticity. Despite these challenges, the project demonstrates the potential of modular synthesis as a viable alternative to field recordings. This work contributes to a deeper understanding of the design principles and tools required for credible synthetic sound design.