ACOUSTICS

**__Definitions:__**


 * Speed: ** Distance travelled in unit time (m/s).
 * Frequency: ** Number of complete waves in one second (Hz).
 * Wavelength: ** Distance between matching poins on the wave (m).
 * Longitudinal: ** Vibration parallel to direction of travel.
 * Transverse: ** Vibration of rigth angle to direction of travel.

**ALL ABOUT SOUND **  Room acoustics, how sound behaves in a room. This includes the way humans perceive different acoustic phenomena. There are important aspects involved in the propagation of sound as sound transmission, sound absorption, sound reflection and sound diffusion. The field of building acoustics also covers sound insulation too.

**ROOM ACOUSTIC DESCRIPTORS**  These descriptors can be used to formulate room acoustic specifications and to check the effect of different procedures. As regards acoustic design, it is an advantage if different designs and procedures can be evaluated objectively. For this purpose, a number of measurable room acoustic descriptors have been defined. <span style="font-family: 'Comic Sans MS',cursive;">

1. <span style="font-family: 'Comic Sans MS',cursive;">__Reverberance:__ Is linked to the speed at which sound energy disappears in a room. An unfurnished room with hard surfaces, such as a church, is perceived as being more reverberant than a well-furnished living room. <span style="font-family: 'Comic Sans MS',cursive;">2. __<span style="font-family: 'Comic Sans MS',cursive;">Speech clarity __<span style="font-family: 'Comic Sans MS',cursive;">: Concerns the quality of speech transfer to the listeners. In a reverberant room with disturbing background noise, it can be difficult to pick up speech. <span style="font-family: 'Comic Sans MS',cursive;">3. __<span style="font-family: 'Comic Sans MS',cursive;">Auditory strength __<span style="font-family: 'Comic Sans MS',cursive;">: Is the level at which we experience sound. A reverberant room gives a higher sound level than a room with added sound absorption. <span style="font-family: 'Comic Sans MS',cursive;">4. __<span style="font-family: 'Comic Sans MS',cursive;">Spatial decay __<span style="font-family: 'Comic Sans MS',cursive;">: The sound level decreases as the distance from the sound source increases. The design of the room (shape, furnishing, surface finish etc.) influences the extent to which the sound level decreases along with the distance.

<span style="color: #0000ff; font-family: 'Comic Sans MS',cursive; font-size: 120%;">**SOUND INSULATION** <span style="font-family: 'Comic Sans MS',cursive;"> Soundproofing relates to the overall ability of a building element or building structure to reduce the sound transmission through it. Two types of sound insulation might be referred to - airborne sound insulation and impact sound insulation.

<span style="font-family: 'Comic Sans MS',cursive;">1. __Room-to-room insulation__: In many cases a continuous suspended ceiling is chosen in order to achieve maximum flexibility. However these constructions will give lower sound insulation compared to constructions where the partitions are allowed to penetrate the suspended ceiling or reach all the way up to the soffit.

2. __<span style="font-family: 'Comic Sans MS',cursive;">One-way sound insulation: __<span style="font-family: 'Comic Sans MS',cursive;"> Installations in the void between the structural soffit and the suspended ceiling, such as piping and ductwork systems, can give rise to noise. In such cases, a sound insulating suspended ceiling system can be used to reduce the noise to acceptable levels in the room below.

<span style="font-family: 'Comic Sans MS',cursive;">3. __Vertical airborne sound insulation__: The airborne sound insulation of a floor structure can be improved by means of a suspended ceiling system. Airborne sound insulation may relate to sounds generated in both the room below and the room above. Improvements are always linked to a specific type of floor structure.

<span style="font-family: 'Comic Sans MS',cursive;">4. __Impact sound insulation__: Impact sound insulation relates to the reduction of footstep sound from people walking on a floor structure. It is determined by the impact sound level in the room below. A suspended ceiling system can be used to improve the impact sound insulation and therefore reduce the impact sound level. Improvements are always linked to a specific type of floor structure.

<span style="color: #0000ff; font-family: 'Comic Sans MS',cursive; font-size: 120%;">**ROOM ACOUSTIC DESING**

<span style="font-family: 'Comic Sans MS',cursive;">**__Different acoustic room types.__** <span style="font-family: 'Comic Sans MS',cursive;">The way sound behaves and affect the people in the room depends heavily on the room geometrie and placement of absorption material.

<span style="font-family: 'Comic Sans MS',cursive;">(a). **Hard rooms:** A room with little sound absorption, a “hard room” in which the surfaces reflect most of the noise. <span style="font-family: 'Comic Sans MS',cursive;">(b). **Rooms with absorbing ceilings:**This type acts differently than the hard room and, as a rule, requires several descriptions for an acoustic assessment. <span style="font-family: 'Comic Sans MS',cursive;">(c). **Open-plan rooms****:** A third type is a room with extended forms such as open-plan areas and corridors.

<span style="font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">__**Choosing the right sound absorption**__ <span style="font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Using absoprtion class A means that less material is needed and quality of teaching, working and healing is optimised. <span style="font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;"> <span style="font-family: 'Comic Sans MS',cursive;">A fully covered absorbing ceiling is the preferred solution for placement of sound absorption material. Sometimes, the design might require additional or alternative solution. <span style="font-family: 'Comic Sans MS',cursive;">
 * __<span style="font-family: 'Comic Sans MS',cursive;">Acoustic design with wall panels and acoustical rafts __**

<span style="color: #0000ff; font-family: 'Comic Sans MS',cursive;">**<span style="color: #0000ff; font-family: 'Comic Sans MS',cursive; font-size: 120%;">MAKE THE RIGTH ROOM ACOUSTIC DEMANDS FROM THE START **



<span style="font-family: 'Comic Sans MS',cursive;"> It is vital to clearly specify your requirements for room acoustic quality early on in the building process. Acoustics in one form or another are either directly or indirectly represented in working environment legislation, building regulations, guidelines and standards. It may be that you need to set stricter requirements than those officially dictated in standards and regulations. <span style="font-family: 'Comic Sans MS',cursive;"> Depending on what will be going on in the rooms, room acoustic properties such as sound level, reverberance or speech clarity may need to be given different priority. Should sound levels be low? Does speech need to be clearly intelligible? Is a room full of reverberance a plus or a minus for the activity? Does sound propagation need to be prevented, particularly in large open rooms? These are the questions that need to be asked when requirements are being specified early on in the building process.

<span style="color: #0000ff; font-family: 'Comic Sans MS',cursive; font-size: 120%;">**HOW TO IMPROVE ACOUSTICS** <span style="font-family: 'Comic Sans MS',cursive;"> Simply speaking, any sound that is unwanted, or in excess, is "noise." There are two types of sound paths: airborne sound and structure-borne sound. Airborne sound is directly transmitted from a source into the air. All sound that reaches your ear is airborne. Some examples of airborne sound are passing traffic, music or voices from an adjacent room, or the noise from machinery and aircraft.

<span style="font-family: 'Comic Sans MS',cursive;"> Structure-borne sound, also known as "impact noise," is sound that travels through solid building materials such as footsteps on floors, door slams, plumbing and mechanical equipment vibrations, and the impact of rain and weather on a building.

<span style="font-family: 'Comic Sans MS',cursive;"> Some practical sound control techniques that will improve the airborne sound transmission resistance of wall and floor-ceiling assemblies include:

<span style="font-family: 'Comic Sans MS',cursive;">1. Constructing partition walls with lightweight steel framing instead of wood studs. <span style="font-family: 'Comic Sans MS',cursive;">2. Adding sound absorbing fiberglass insulation to wall and ceiling cavities. <span style="font-family: 'Comic Sans MS',cursive;">3. Constructing airtight building assemblies by sealing around windows and doors, as well as any penetration through the assembly. Sound energy will always find the holes and take the path of least resistance. <span style="font-family: 'Comic Sans MS',cursive;">4. Structurally breaking the tie between finished drywall surfaces and wood framing using resilient channel or acoustically engineered gypsum board.

<span style="font-family: 'Comic Sans MS',cursive;"> Some practical sound control techniques that will reduce impact sound transmission through floor-ceiling assemblies include:

<span style="font-family: 'Comic Sans MS',cursive;">1. Installing thick carpeting and padding. <span style="font-family: 'Comic Sans MS',cursive;">2. Structurally disconnecting floors and ceilings with resilient underlayments and isolated suspended ceiling systems. <span style="font-family: 'Comic Sans MS',cursive;">3. Isolating plumbing and electrical conduits from structures with resilient pads and hangers.

<span style="font-family: 'Comic Sans MS',cursive;"> Improve the acoustical performance of room spaces using solutions that include:

<span style="font-family: 'Comic Sans MS',cursive;">1. Suspending sound absorbing acoustical ceiling tile systems. <span style="font-family: 'Comic Sans MS',cursive;">2. Installing carpeting in open plan spaces to cover hard surfaces. <span style="font-family: 'Comic Sans MS',cursive;">3. Installing acoustically absorptive wall partitions and coverings to dampen sound energy. **<span style="color: #0000ff; font-family: 'Comic Sans MS',cursive; font-size: 120%;">Interview: Professor Murray Hodgson **

**<span style="color: #000000; font-family: 'Comic Sans MS',cursive;">Note taking **

<span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Acoustical spaces, psycho acoustics <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Sound in a space is noise? Usefull sound or bad sound <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Echoing affects the sound in a room <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Noisy place = bad acoustic design? Depends on the point of view <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Sometimes noise is usefull because it gives a little more privacy. If we quit all the noise, probably we will fell like everybody can hear us <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Noise is unwanted sound <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">A building is a physical system but the users are not <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Requeriments for the needs of the people. You can’t cause auditive damage. This could also affect the emotions. <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">It’s needed to be carefull with sound reflection in certain places. <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">Depends of the priorities. Health is primordial when designing a building. <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">There’s no need to be extremist. Nobody wants to be in a concert hall and feel totally isolated <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">The noise can reduce the quality of life. <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">The acoustical environment specially of a building is something that can be designed with the architectural forms, the materials and the right equipment.

**<span style="color: #000000; font-family: 'Comic Sans MS',cursive;">Main idea ** <span style="color: #000000; font-family: 'Comic Sans MS',cursive; font-size: 13px; vertical-align: baseline;">The interview is about the point of view of a physic, Prof. Murray Hodgson, in the area of acoustics. He gives us the opinion of a scientist about the acoustic in architecture. In physics, buildings are physical systems and in this sense, noise is unwanted sound, but the problema is that the users of a building are humans, not machines, so, is necesary to think in their needs, because, health and emotions are primordial. For him, the noise is caused basically for the echo and the sound reflection, but this can be avoid by taking care on the architectural forms, the isolating materials and the right equipment. He also says that a noisy place not necessarily implides a bad acoustic design, because in certain levels, noise can be used to give privacy to the people in a room. For example, if we are talking in a restaurant and suddenly the noise disappears, we wiil feel like everybody can hear us. In conclussion, the answer is in the equilibrium because noise can reduce the quality of life but also could be usefull in some environments.