An open development platform for auditory real-time signal processing

Abstract

Algorithms that are used in real-time hearing devices, such as hearing aids or cochlear implants, need to work with a short time latency in the order of 10ms and must be efficient enough to run on battery power. Furthermore, in order to evaluate ecological validity such algorithms often need to be validated in the development stage using real-time processing of environmental sounds. However, researchers often lack the ability to access to the technology and they use offline schemes instead. In order to allow more and less specialised researchers access to the necessary technology and make it as easy and straightforward to develop real-time algorithm, we have developed an auditory real-time processing algorithm platform ("Open Development Platform", ODP). The ODP is designed to help the development from existing offline algorithms to novel real-time algorithms by introducing a clear set of rules for development and evaluation. ODP has a software component that works in MATLAB/Simulink and a hardware component that works on the Speedgoat® Target machine. We also explain several algorithms from the available library that have low latency and low power consumption: filter bank, envelop power estimator, frequency shifter, and adaptive feedback canceller. As example of a complete project, we demonstrate here, how they can be combined to a fully functional hearing aid for research purposes.

Wearable Hearing Device Spectral Enhancement Driven by Non-Negative Sparse Coding-Based Residual Noise Reduction

“…An auditory filter bank must have equally spaced narrow frequency bands and at least 60 dB of stopband attenuation (a higher value is ideal) [ 21 ], as mentioned in Section 1 . Furthermore, a filter bank must exhibit low computational complexity and a small time delay of less than 10 ms.…”

“…These signals are then utilized to obtain the power envelope of each band. The term denotes the corresponding spectral output of the hearing aid algorithms, such as a dynamic range compressor and a feedback cancellation algorithm, to and can be converted into the frame signal through an inverse FFT [ 20 , 21 , 22 ]. Finally, the filter-bank-synthesized output signal is derived from the overlap-and-add operation of the LPF applied signal at .…”

“…Furthermore, the objective is to implement the speech enhancement algorithm on an auditory hearing device filter bank that can satisfy unique conditions such as the signal quality, computational complexity, and signal delay. In particular, the latency in auditory processing algorithms should not be more than 10 ms, to prevent a deterioration in the subjective listening experience [ 20 , 21 , 22 , 23 , 24 ]. Moreover, the approaches should have a low computational complexity due to the limited processing capacity and battery power in real-world portable devices [ 22 , 25 , 26 ].…”

“…Moreover, the approaches should have a low computational complexity due to the limited processing capacity and battery power in real-world portable devices [ 22 , 25 , 26 ]. To this end, many researchers employ a discrete Fourier transform (DFT)-based uniform polyphase filter bank, as it can enable perfect reconstruction with low latency and can be expanded into non-uniform filter banks [ 20 , 21 , 26 ]. Furthermore, such banks can be implemented through a short-term Fourier transform (STFT), thereby allowing the integration of single microphone noise reduction algorithms based on a fast Fourier transform (FFT) [ 22 , 26 ].…”

Hearing Aid Speech Enhancement Using Phase Difference-Controlled Dual-Microphone Generalized Sidelobe Canceller

“…The problem has been overcome using electronic auditory devices such as hearing aids, which are widely used to amplify or compress the signal that enters the ear to match the dynamic range and compensate for hearing loss [1]. Hearing aids achieve this by estimating the signal envelop power according to frequency channels, which is based on a filter bank system [2], [3]. Thus, a digital filter bank is an essential algorithm that is frequently addressed when starting the development of a hearing aid auditory signal processing system [2], [3].…”