This paper presents a digital hearing aid chip designed for Mandarin user to enhance speech quality and intelligibility. The hearing aid consists of an 18 subbands analysis and synthesis filter bank, insertion gain stage, and three channels wide dynamic range control for the new Mandarin-specific auditory compensation algorithm. A noise reduction block based on multiband spectral subtraction and enhanced entropy voice activity detection is also included to enhance quality. We reduce the power consumption of these algorithms through algorithmic and architecture optimization. In addition, for the data storage requirement, a low power SRAM that can operate at 0.6V and below is developed. Moreover, several strategies such as multi-clock domain, bypass mode, and voltage scaling are also adopted for power reduction. The chip measurement shows that the hearing aid consumes 314uW at 0.6V.