Engr. Irineo P. Quinto, Engr. Luigi Carlo De Jesus, Engr. Leonardo M. Samaniego Jr.

ABSTRACT: Human sense of hearing is instrumental in various aspects of our lives, enabling us to recognize and locate sounds. This research aims to explore the enhancement of sound amplification and filtering capabilities in hearing aids through a simulation conducted using MATLAB. The study addresses the prevalent issue of hearing loss in the global population, with a focus on improving the limited adoption of hearing aids. By leveraging the digital signal processing capabilities of MATLAB, the project aims to differentiate between speech and background noise, leading to improved audio quality for hearing aid users. The simulation involves three main stages: audio recording, audio filtering, and audio amplification. The MATLAB-based simulation generates output files reflecting the enhanced audio, while also addressing the challenges of potential distortion and the selective cancellation of specific noises. The findings of this research hold the promise for the development of more effective and efficient hearing aid technologies, ultimately improving the quality of life for individuals with hearing impairments.  Keywords: sound amplification, filtering, hearing aids, MATLAB simulation, improved audio quality  Engr. Irineo P. Quinto  Engr. Luigi Carlo De Jesus  Engr. Leonardo M. Samaniego Jr.   Ronald Kenneth M. Aliven  Merwyn Floyd S. Blanco  Sean Karlo T. Conejo   Jex O. De Los Santos  The human sense of hearing is instrumental in various aspects of our lives, enabling us to recognize and locate sounds, thereby preventing potential dangers such as car accidents or fires, as well as aiding in the discovery of objects overlooked by our eyes ​(Lam, 2018)​. However, individuals who lack this ability face difficulties in navigating such situations​ (Smith, 2020)​. Hearing loss manifests in different ways, with some people experiencing difficulty hearing low-frequency sounds, while others struggle with high-frequency sounds, highlighting the variations in hearing impairment​ (Jones, 2019)​. Hearing aids play a crucial role in assisting individuals with hearing deficiencies by amplifying and filtering sounds across different frequency channels ​(Gupta, 2017)​. However, simply amplifying the specific frequency channels is insufficient, as it also amplifies accompanying noises, resulting in distorted and unintelligible sounds ​(Smith, 2020)​. To address this issue, digital filtering is employed to eliminate noise within a given frequency range, ensuring a cleaner audio output ​(Gupta, 2017)​. Once noise cancellation is achieved, appropriate amplification can be applied without the risk of amplifying unwanted noise ​(Jones, 2019)​. Therefore, it is established that digital filtering is a necessary step before performing amplification ​(Lam, 2018)​.  The objective of this research is to enhance an individual’s hearing abilities by improving the functionality of hearing aids. The primary task of a hearing aid is to amplify sound at various frequency ranges, ensuring that speech frequencies can reach the ear, based on the specific degree and configuration of the individual’s hearing loss. This project aims to provide benefits not only to the hearing-impaired individuals but also to the researchers involved, as it seeks to educate them on the principles of audio amplification and ensure the efficient operation of the hearing aids.   The focus of this project lies in leveraging a simulator, namely MATLAB, because of the prevailing pandemic situation. The primary aim is to direct efforts towards the exclusive processing of audio signals. However, it is imperative to acknowledge the intrinsic limitations that accompany this approach. While the results achieved through the simulator may exhibit similarities to real-life situations, it is important to note that they may not entirely replicate the authentic utilization and experiential elements associated with the use of an actual physical hearing aid.  B.1. Block Diagram  Figure 1   MATLAB Simulink Block Diagram  The block diagram of a hearing aid system consists of four main blocks: the original output block, amplifier block, parallel digital bandpass filter block, and hearing aid speaker block. The original output block represents the input sound signal captured by the microphone. This block converts the acoustic signal into an electrical signal, which serves as the initial input for further processing. The electrical signal then enters the amplifier block, where it undergoes amplification. The purpose of the amplifier is to increase the strength of the signal to a level that can be effectively processed by the subsequent blocks. Next, the signal is divided into multiple parallel paths in the parallel digital bandpass filter block. Each path represents a specific frequency range that requires specialized processing. The bandpass filters within this block isolate and extract the desired frequency components from the signal, while attenuating frequencies outside the desired range. This enables targeted signal enhancement and noise reduction. After the signal has been processed by the bandpass filters, it is directed to the hearing aid speaker block. This block converts the electrical signal back into an acoustic signal, which is then delivered to the user’s ear. The speaker produces sound waves based on the processed signal, allowing the user to perceive the amplified and filtered sound.  Overall, the block diagram showcases the sequential flow of the sound signal through the different processing stages of the hearing aid system. Starting from the original output, the signal passes through amplification, parallel digital bandpass filtering, and finally, to the hearing aid speaker, resulting in an enhanced and tailored audio experience for the individual with hearing impairment.  B.2. Bandpass Filter Design  The bandpass filter is a digital filter that has been specifically chosen for its ability to isolate and process signals within a designated frequency range. Its primary function is to remove unwanted noise effectively while emphasizing frequencies crucial for speech and sound perception. In this research, a configuration involving two parallel bandpass filters has been implemented, as depicted in Figure 1.  The inclusion of two parallel bandpass filters offers several advantages, including enhanced noise reduction and a targeted response to specific frequencies. Each filter is meticulously designed to cater to a particular frequency range, ensuring that the desired speech frequencies are accentuated while minimizing the impact of noise outside those ranges. By adopting this configuration, the objective of the research is to optimize the filtering process and enhance the overall performance of the hearing aid system.  The parallel arrangement of the bandpass