The critical challenge with the continuously increasing number of Internet users is copying and duplication, which has caused content integrity and protection. To manage and secure the signals from unauthorized consumers of digital content, we require certain procedures. Digital watermarking scheme on vowel-based approach can address these problems. Thus, we can provide a robust and secure method that solves the issues of copyright, illegal intentional or unintentional modification. In this paper, we have proposed vowel-based speech watermarking techniques using the FFT method with the help of the Min algorithm. We observe that the proposed FFT-based watermarking scheme provides better results in comparison to the existing methods.