Abstract: Acoustic demultiplexers, pivotal for enhancing the capacity and efficiency of communication systems, face significant challenges in their conventional design approaches. These approaches are hindered by the complex nature of wave-matter interactions, leading to high computational costs and prolonged design cycles. This study proposes a hybrid inverse design approach integrating topology optimization and shape optimization, effectively avoiding grayscale issues in topology optimization while overcoming insufficient design freedom in shape optimization, thereby achieving co-optimization of global material distribution and local geometric details. Using this method, a three-port acoustic demultiplexer achieving complete isolation of acoustic signals at frequencies of 800 Hz and 1000 Hz is designed. To address the need for signal separation across broader frequency spectra, this study further extended the design to develop a three-port broadband acoustic demultiplexer capable of efficiently isolating acoustic signals within two distinct frequency ranges: 800−900 Hz and 900−1000 Hz. Finally, targeting more complex multi-frequency signal separation scenarios, a five-port acoustic demultiplexer was obtained using an inverse design approach. This device successfully achieves complete separation of four distinct acoustic signals at frequencies of 4500 Hz, 5000 Hz, 5500 Hz and 6000 Hz.