AED122 Lesson 5: Understanding Sound Environment PDF

COLLEGE OF ARCHITECTURE ENGINEERING & DESIGN AED122: Lesson 05: Understanding Sound Environment Dilshan R. Ossen, Ph.D Associate Professor Scope of the Lesson Sound & Noise in Built Envi...

COLLEGE OF ARCHITECTURE ENGINEERING & DESIGN AED122: Lesson 05: Understanding Sound Environment Dilshan R. Ossen, Ph.D Associate Professor Scope of the Lesson Sound & Noise in Built Environment Principles of sound Measurement of sound Material Properties  Sound & Noise in Built Environment Sound environment is one of the most important physical elements in and around buildings. People are exposed to the sound in everyday life and normally communicate by sound. We interpret sound through our sense of Hearing. Hearing is open to subjectivity in terms of likes & dislikes.  Sound is a movement of energy that caused by vibration and transmitted through a solid, liquid or gas; that is capable of being detected by ears Noise is a term often used to refer to an unwanted sound. In science and engineering, noise is an undesirable component that obscures a wanted signal. Acoustics is the scientific study of the propagation, absorption, and reflection of sound waves  Noise Pollution Source: "Noise Pollution Is Much Worse For You Than You Think" on YouTube https://youtu.be/5jfmzufa8qo  Effect of unwanted sound on people and Built Environment Elevated sound (noise) can cause hearing impairment, hypertension, schemic heart disease, annoyance, sleep disturbance, and decreased performance. Elevated sound levels can create stress, increase workplace accident rates, and stimulate aggression and other anti-social behaviors Effect on quality of life: creating unpleasant and undesirable environments.  Interference: interference with significant sounds such as speech or music can be annoying and dangerous Distraction: distraction from particular task can cause inefficiency Effect on economy: measures need to control excessive noise are expensive  Noise Issues & Urban Environment Policies Wh there is a low polic priorit for noise’? Limited knowledge about exposure to noise, limited measurements of its effect compared with other pollution problems Large number of sources of noise which makes difficult to take coherent action Lack of training The absence of major accidents due to noise Temporary nature of noise Future Challenges With urbanization, technological advancement and population growth – Source of noise become increasingly powerful – Sources will dispersed over larger areas; urban to rural, to natural to leisure areas – Spread over time; throughout the day and weekends – Public demand for better quality environment and a quieter environment will increase What is a good sound environment? 1. To protect from unwanted sound, i.e. noise 2. To provide suitable sonic conditions to the occupants for their purposes. Perception of Sound Hearing is one of the most crucial means of survival in the animal world For humans, hearing is limited to frequencies between; 20 Hz to 20,000 Hz  Other species have a different range of hearing. For example, dogs can perceive vibrations higher than 20 kHz. As a signal perceived by one of the major senses, sound is used by many species for detecting danger, navigation, predation, and communication. Sound Sources in Built Environment Sound Sources in Built Environment External sounds/noises: sources of sound are outside the buildings, such as from a road (traffic noise, commercial centers), aircraft (aircraft noise), railroad (railway noise), weather, playground, workshops, etc. Internal sounds/noises: sources of sound are within the buildings, such as noise from occupants, building services, etc. Sound/noise sources in Built Environment  Sound Environment Study Concentrates on Two Aspects: 1). “Noise control” : examines means to reduce the noise levels in and around buildings. 2). “Room acoustics”: aims to create suitable sound conditions within an enclosed space such as music hall or auditorium. Fundamental concepts of acoustics Interaction of Sound with Medium Sound Transmission Airborne Sound Impact Sound Flanking transmission Airborne Sound Airborne sound sources produce noise by vibrating the surrounding air; – speech, televisions and home entertainment systems Airborne sound insulation is concerned with reducing this sound transmission through separating floors and walls Impact Sound Impact sound sources produce noise by direct physical excitation of a part of a building – footsteps on a floor, hammering, the dropping of an object or the moving of furniture Impact sound insulation is concerned with resisting this impact sound upon separating floors. Flanking Transmission – Structure Borne Noise Flanking transmission occurs when sound is transmitted from one space to another indirectly, through adjoining parts of the structure. impact sound may be transmitted from one room to another through a timber floor, but also through the supporting wall. Summary Noise is a subset of sound Noise is unwanted sound. It has a clearly negative connotation unlike sound. Understanding Noise Issues: Noise is harmful to humans in many ways. Sound in its most natural and ordinary state is pleasant and good to hear. Effect of different sound levels: Noise has a bigger decibel mark than most ordinary sounds. What is a good sound environment? Read more: Difference Between Sound and Noise | Difference Between | Sound vs Noise http://www.differencebetween.net/language/words-language/difference-between-sound- and-noise/#ixzz5jv0UKPpU