A 1.5 mW Programmable Acoustic Signal Processor for Hearing Assistive Devices With Speech Intelligibility Enhancement

This paper presents a low-power, programmable acoustic signal processor for hearing assistive devices with speech intelligibility enhancement. The reprogrammable design provides considerable flexibility for the devices to deal with personal conditions of hearing loss. A spectral-change enhancement (SCE) algorithm is implemented to improve speech intelligibility. The power consumption is minimized by adding dedicated hardware accelerators. The short-time objective intelligibility (STOI) measure is utilized for optimizing the datapath architecture. Optimization on the critical MAC operations results in 34% power and area reductions when compared to the direct-mapped design. A 50% reduction in SRAM storage is also achieved owing to the reduced memory storage for the associated MAC operations. With the aid of the optimized MAC unit and data buffer, the overall execution time is reduced by 99.2%. Designed in a 40-nm CMOS technology, the processor integrates 431k gates in area of 0.3 mm2. The design dissipates 1.5 mW at a clock frequency of 10.5 MHz from a 0.7V supply, with a processing latency of 1.05 ms.