Recently, various ways to reduce the size of multimedia data have been developed. However, there is a problem of the tradeoff of data size, and quality. In compressed audio encoding, high frequency components are lost from the original signal. It is impossible to retrieve the frequency components that have been cut using the conventional interpolation method (Shannon?s method). We review the Fluency sampling function, which is a locally supported function of second order. Although the use of this function will not retrieve the cut frequency components, it has a special nature that the reproduced signal includes ultrasonic components of higher frequency. Therefore, we can expect the subjective enhancement of sound quality for encoded audio data. The small support of the function is also an advantage when using on portable devices such as cell phones, as the number of calculation can be drastically saved when compared with the conventional method.