## 6 Conclusions  
In this study, we explored N-level cascaded chaotic-based secure communication systems for voice encryption employing a 4D unified hyperchaotic system. This adaptable structure accommodates chaotic oscillators of varying dimensions, offering flexibility in implementation. Through numerical simulations in Matlab/Simulink, we applied this unified hyperchaotic oscillator to voice encryption and evaluated system performance across key metrics, including Signal-to-Noise Ratio (SNR), Peak Signal-to-Noise Ratio (PSNR), Percent Residual Deviation (PRD), correlation coefficient, FPGA resource utilization, and clock frequency. A novel performance metric, Value-Based Performance Metrics (VBPM), was introduced to consolidate these parameters into a single value for easier comparison. Our findings show that while security improves with an increase in cascaded levels, the optimal performance was achieved at N = 4, with diminishing returns beyond this point. Compared to existing methods, our system performed favorably, particularly in terms of correlation coefficient and SNR, underscoring its potential for enhancing secure communications. The broader implications of this research are significant for secure communication systems, particularly in fields such as military, governmental, and financial voice encryption. By cascading chaotic oscillators, our system enhances security, making unauthorized decryption more difficult. However, the system's scalability is limited by increasing encryption/decryption time and FPGA resource consumption, especially beyond N = 7. This highlights the need for more advanced hardware or optimized designs for real-time applications. In the future, the integration of quantum encryption with chaos-based methods offers a promising avenue for further enhancing communication security [48]. Quantum encryption mechanisms, driven by breakthroughs in quantum teleportation and quantum computing, could be combined with chaos-based encryption to build advanced systems for securing multimedia files. This could represent the next evolution in secure communication systems, offering unprecedented levels of security. Further work could focus on optimizing the system for faster encryption and more efficient resource use, exploring alternative chaotic oscillators, and extending the approach to other types of data, such as image and video encryption.  
[PERSON] contributed to the conceptualization of the study, developed the methodology, supervised the research, managed the project, and participated in writing, reviewing, and editing the manuscript. [PERSON] was involved in the development of the methodology and played a significant role in writing the original draft of the manuscript. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
This article does not contain any studies involving human or animal participants performed by any of the authors. Thus, ethical approval was not applicable.  
The data presented in this study are available on request from the corresponding author as they are part of ongoing research.  
Conflicts of Interest: I declare that the authors have no competing interests or other interests that might be perceived to influence the results and/or discussion reported in this paper.