ABSTRACT

Noise has been defined as an unwanted signal. Sound noise is a major societal problem, whose health, environmental and even economic impact is very important. According to the World Health Organization (WHO), noise is an acoustic phenomenon that produces an uncomfortable hearing sensation. Populations whose buildings are housed in areas at high risk of noise are exposed to multiple diseases resulting from noise pollution. To remedy this, it is important to think of choosing the right materials with higher acoustic absorption coefficient. This work is aimed at building a sound absorber system for electrical communication lab

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

1.0    INTRODUCTION

1.1    BACKGROUND OF THE STUDY

• PROBLEM STATEMENT
• AIM AND OBJECTIVES OF THE STUDY
• PROJECT MOTIVATION
• SCOPE OF THE STUDY

CHAPTER TWO

• LITERATURE REVIEW
• REVIEW OF THE STUDY
• REVIEW OF RELATED STUDIES
• ACOUSTIC MATERIAL
• HISTORICAL BACKGROUND OF ACOUSTIC MATERIALS
• ACOUSTIC MATERIAL AND THEIR DIFFERENT TYPES
• PROPERTIES OF ACOUSTIC MATERIAL
• ACOUSTIC FORM

CHAPTER THREE

• MATERIALS AND METHODS
• MATERIALS
• TOOLS USED
• REQUIREMENT OF A GOOD ACOUSTIC MATERIAL
• METHOD USED

CHAPTER FOUR

• RESULT AND DISCUSSION

CHAPTER FIVE

• CONCLUSION AND RECOMMENDATION

REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

Acoustical materials are a variety of foams, fabrics, metals, etc. used to quiet workplaces, homes, automobiles, and so forth to increase the comfort and safety of their inhabitants by reducing noise generated both inside and outside of those spaces. Acoustical materials are used in two major ways: as soundproofing, by which noise generated from outside a given space is blocked from entering the space; and, as sound absorbing, where noise generated within a space is reduced inside the space itself (Gobain, 2012).

Sound and noise are managed by four methods: blocking, absorbing, diffusing, and isolating.

• Blocking relates to the use of soundproofing.
• Absorption works by converting sound energy into heat.
• Diffusion seeks to scatter sound without deadening a room.
• Isolating is done at the source of the noise itself, by placing a compressor on isolation mounts, for instance.

Acoustic absorption refers to the process by which a material, structure, or object takes in sound energy when sound waves are encountered, as opposed to reflecting the energy. Part of the absorbed energy is transformed into heat and part is transmitted through the absorbing body. The energy transformed into heat is said to have been ‘lost’.

When sound from a loudspeaker collides with the walls of a room part of the sound’s energy is reflected, part is transmitted, and part is absorbed into the walls. Just as the acoustic energy was transmitted through the air as pressure differentials (or deformations), the acoustic energy travels through the material which makes up the wall in the same manner. Deformation causes mechanical losses via conversion of part of the sound energy into heat, resulting in acoustic attenuation, mostly due to the wall’s viscosity. Similar attenuation mechanisms apply for the air and any other medium through which sound travels (Gobain, 2012).

The fraction of sound absorbed is governed by the acoustic impedances of both media and is a function of frequency and the incident angle (Parker, 2009). Size and shape can influence the sound wave’s behavior if they interact with its wavelength, giving rise to wave phenomena such as standing waves and diffraction.

Acoustic absorption is of particular interest in soundproofing. Soundproofing aims to absorb as much sound energy as possible converting it into heat or transmitting it away from a certain location.

In general, soft, pliable, or porous materials serve as good acoustic insulators – absorbing most sound, whereas dense, hard, impenetrable materials reflect most.

However, the noise produced by industries, streets, construction sites, garages, handling sites, individuals or groups of individuals, and even aircraft become more troublesome or even harmful for to neighboring people according to the level where they are located. Indeed, the ear is adversely affected by noise level greater than 120 dB (decibels). This can lead to rupture of the eardrum (Houngan et al., 2013). As such, inhabitants of buildings located in the vicinity of the endless sources of noise are constantly exposed to unpleasant acoustic effects that will lead sooner or later diseases. To remedy this, it urges to think about the choice of the appropriate materials with a significant acoustic coefficient to ward off the harmful effects caused by sound rumors over the health of the population, during the construction of residential buildings in areas with high risk of noise.

For any building, contractors must check the standards on insulation against aerial noises and shock-related noises, insulation of facades, noise produced by technical equipment or reduction of some local reverberation (NBN, 2017).

In a school Lab, how well the Lab absorbs sound is quantified by the effective absorption area of the walls, also named total absorption area. This work discusses the construction of a sound absorber or acoustic system for electrical communication lab using acoustic (Melamine foams) as the main acoustic material.

1.2                                                  PROBLEM STATEMENT

Loud noise can increase stress, anxiety, and blood pressure, and put people at greater risk of stroke and heart disease. Conversely, a well-designed building with the proper acoustics can influence a person’s mental health and overall sense of well-being for the better.

No one enjoys noise in any form. In the area of the building (Electrical Communication Lab), noise from walking, conversation, equipment are the sources of annoyances that can go from a deterioration in the quality of life to direct effects on the health of occupants. As such, the fight against noise is an important issue which translates into regulations, acoustic standards that set minimum acoustic performance expected inside the buildings so as to provide the acoustic comfort for the occupants and users.

1.3                                    AIM AND OBJECTIVES OF THE STUDY

The main aim this work is to build a sound absorber or acoustic system for electrical communication lab. The objectives of the work are:

1. To design a sound absorber in our electrical communication lab using form and other acoustic materials
2. To reduce environmental noise

• To increase human comfort.

1.4                                                  PROJECT MOTIVATION

Buildings without sound absorption are vulnerable to excessive reverberation because there’s nothing to remove the sound from the room before it can bounce back — thereby creating a noisier, busier environment. This can make it more difficult to hear spoken communication, make it harder to focus, and add to stress levels as a result.

Sound insulation is the property in a wall that allows it to keep noise from passing from one side to the other by absorbing sound waves of different frequencies. It can impact acoustic design by blocking air paths between rooms or between a room and the building’s exterior.

The effectiveness of sound insulation is measured in terms of dB Dw, with dB referring to decibels and Dw signifying the difference between the noise level in the room where sound is being produced and the level in a second, adjacent room, where it’s being heard or received.

The term sound insulation refers to how much sound is lost when it travels between the source room and adjacent room. If the dB Dw between two rooms is 45, that might mean the sound level is 65 dB in the source room and 20 in the adjacent room during a typical speech.

Sound waves need a medium through which to travel, most typically air. As a result, sound can travel through vents and electrical outlets or under doors — anywhere air can go. Sealing such spaces and adding insulation to venting systems are therefore effective ways of reducing unwanted sound.

When a building includes sound insulation, it can minimize distractions from sound that emanates from adjacent rooms, whether it’s music, speech, or mechanical noise.

Acoustic insulation boards consisting of fiberglass panels and wrapped in cloth, as mentioned above, can absorb sound and effectively insulate adjacent rooms from the sound created in each of them, reducing background noise and improving focus.

Acoustic boards and foams  are specifically designed with materials that absorb sound. They can be used in a number of spaces, including on walls or ceilings — especially at points where sound is known to reverberate — to reduce unwanted noise and create added clarity.

This study is used to identify local materials with significant acoustic coefficients that can be used to improve the acoustic comfort of electrical communication Lab.

This research work will throw more light on the best techniques for absorbing noise most especially in our school Lab. This study will also be designed to be of immense benefit to all builders, user and residents of any building.

1.5                                                   SCOPE OF THE STUDY

This study was carried out to absorb external sound coming from the school environment to the electrical communication lab. Melamine foams which the also known as acoustic form were used together with other materials such as Wood, Ply wood and Clothing material.