Digital hearing-aid unequal-width sub-band automatic gain control method

Abstract

The invention provides a digital hearing-aid unequal-width sub-band automatic gain control method. The method includes: designing an unequal-width analysis filter bank according to human ear auditory characteristics, conducting segment processing to input acoustical signals, filtering each segment acoustical signal by using the analysis filter bank to obtain signals of various sub-bands, counting input signal sound pressure level inside the various sub-bands, conducting sub-band automatic gain adjustment according to the sub-band signal sound pressure level, finally using a synthesizing filter bank to synthesize adjusted sub-band signals to obtain system output signals. According to the digital hearing-aid unequal-width sub-band automatic gain control method, noise and voice signals are isolated out through the sub-band filter bank, and thus the gains of noise frequency ranges and the voice signals are respectively controlled, and the roles of noise suppression and signal-to-noise ratio improvement are played. Compared with a traditional equal-width sub-band filter bank partition method, an unequal-width filter bank sub-band partition method used by the digital hearing-aid unequal-width sub-band automatic gain control method coincides with the human ear auditory characteristics. On the premise of obtaining the same effect, the amount of sub-bands need parting and the calculated amount are reduced. In addition, the digital hearing-aid unequal-width sub-band automatic gain control method is achieved totally by a software program with no need of adding an additional hardware circuit, thereby saving the cost, weight and size of a product.

Description

technical field [0001] The invention relates to an automatic gain control method of an acoustic signal, in particular to a non-equal-width sub-band automatic gain control method in a digital hearing aid system. Background technique [0002] Automatic Gain Control (AGC) is a control method that automatically adjusts the gain of the amplifier circuit according to the signal strength. Automatic gain control is a closed-loop system, which is divided into two parts: a gain-controlled forward amplification unit and a gain control unit. The forward gain A of the gain-controlled forward amplification unit is adjusted by the gain control unit. The gain control unit calculates the gain according to the input signal strength, and reduces the forward gain A of the forward amplification unit when the signal strength exceeds the threshold. The purpose of automatic gain control is to prevent the output of the amplifying circuit from exceeding the threshold by reducing the gain when the i...

AI Technical Summary

Problems solved by technology

If the wearer uses the hearing aid in a noisy environment, the traditional automatic gain control method will cause a large loss to useful sound signals (such as speech signals) while suppressing noise, reducing the user's understanding of noisy speech

Therefore, the traditional automatic gain control method can only control the sound pressure level of the output signal, and cannot suppress noise and improve the signal-to-noise ratio.

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