Acoustics

**Speed**: rapidity in moving, going, traveling, proceeding, or performing.


 * Frequency: **is the number of occurrences of a repeating event per unit  time.

**Wavelength**: is the distance between matching points on a wave. This is sometimes called lambda and it's meassured in metres.

**Longitudinal:** longitudinal waves vibrate parallel to the direction of the travel of the wave. Sound waves are longitudinal.

**Transverse**: a  transverse wave is a moving wave that consists of oscillations occurring perpendicular (or right angled) to the direction of energy transfer. A transverse wave forms a regular up-and-down pattern in which the oscillation is perpendicular to the direction the wave is moving.

**Notes:**

** All about Sound **
====Room acoustics are about the way in which sound behaves in a room. Sound transmission, sound absorption, sound reflection and sound diffusion are all aspects that are important here. Room acoustics also include how we as humans perceive different acoustic phenomena. ====

The sounds affect the daily activities of the people, therefore be created the adequate spaces. 

Different types of room will create such different sound fields that this in itself requires different descriptors. We can identify three different basic acoustic types.
 * Different acoustic room types **

__Hard rooms __ is a room with little sound absorption, the surfaces reflect most of the noise.

__Rooms with absorbent ceilings __<span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;"> is a room with a sound-absorbing ceiling.

__<span style="font-family: Arial,sans-serif; font-size: 12pt;">Open-plan rooms __<span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;"> is a room with extended forms such as open-plan areas and corridors.


 * What is sound insulation? **

__<span style="font-family: Arial,sans-serif; font-size: 12pt;">Room-to-room insulation __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">How to avoid unwanted sounds from adjacent rooms.

__<span style="font-family: Arial,sans-serif; font-size: 12pt;">One-way sound insulation __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">Suspended acoustic ceilings help to avoid noise coming from installations. __<span style="font-family: Arial,sans-serif; font-size: 12pt;">Vertical airborne sound insulation __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">Airborne sound insulation may relate to sounds generated in both the room below and the room above

__<span style="font-family: Arial,sans-serif; font-size: 12pt;">Impact sound insulation __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">A suspended ceiling system can be used to improve the impact sound insulation and therefore reduce the impact sound level.


 * Room acoustic descriptors **

<span style="font-family: Arial,sans-serif; font-size: 12pt;">A number of measurable room acoustic descriptors have been defined. These descriptors can be used to formulate room acoustic specifications and to check the effect of different procedures.

[[image:acoustic_5.png]] __Reverberance__
<span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">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: Arial,sans-serif; font-size: 12pt;">Speech clarity __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">Speech clarity 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: Arial,sans-serif; font-size: 12pt;">Auditory strength __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">Auditory strength 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="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;"> __<span style="font-family: Arial,sans-serif; font-size: 12pt;">Spatial decay __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">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="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">A material's sound absorbing properties are expressed by the sound absorption coefficient, //<span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">α //<span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">, (alpha), as a function of the frequency. //<span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">α //<span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;"> ranges from 0 (total reflection) to 1.00 (total absorption) <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">The sound absorption coefficient can be measured by two very different methods - the room method and the tube method. The room method is normally used for presenting product information (as in this publication) and as input to calculation models. The measuring method follows an international standard designated EN ISO 354.
 * <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">Sound absorption **

__<span style="font-family: Arial,sans-serif; font-size: 12pt;">Vertical acoustics __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">The use of absorbing wall panels is suitable in case a fully covered acoustic ceiling is not possible.
 * <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">Acoustic design with wall panels and acoustical islands **

__<span style="font-family: Arial,sans-serif; font-size: 12pt;">Acoustical Islands __ <span style="color: #363636; font-family: Arial,sans-serif; font-size: 12pt;">The use of free-hanging units provides flexibility and a multitude of acoustical solutions to problems related to acoustical design.

<span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt; line-height: 0px; overflow: hidden;">
 * <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">Make the right room acoustic demands from the start **

<span style="font-family: Arial,sans-serif; font-size: 12pt;">Is essential the adaptation of the spaces to the adequate acoustic form since its creation. <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">Setting strict and carefully considered room acoustic requirements need not necessarily mean additional costs. It can be a smart move to add several relevant room acoustic descriptors to the specification of requirement in order to ensure a good environment for the end-user. <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">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.

<span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">Reverberation time will generally work well as a descriptor of room acoustics <span class="apple-converted-space" style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">. <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">Sound level and reverberation time are largely dependent on the total sound absorption in the room. If you know the reverberation time and the power of the sound being emitted from the source, the sound level in the room can be calculated. <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">-The reverberation time depends not only on absorption, but also furnishings, the location of the absorbers and the shape of the room <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">-The more absorption in the room, the lower the sound level <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">-By only assessing the reverberation time, you ignore acoustic information that is important for subjective perception <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">-Despite having the same reverberation time, rooms can subjectively be perceived differently <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">-In open-plan rooms, descriptors linked to the sound's propagation are more important than reverberation time.
 * <span style="background-color: white; font-family: Arial,sans-serif; font-size: 12pt;">Reverberation time and Room Acoustic Comfort **


 * <span style="font-family: Arial,sans-serif;">How to improve acoustics **

<span style="color: #282b2e; font-family: Arial,sans-serif;">A building’s acoustics can have a large impact on the well-being, happiness, and productivity of its occupants.
====<span style="color: #282b2e; font-family: Arial,sans-serif;">There are two types of sound paths: airborne sound and structure-borne sound. Airborne sound is directly transmitted from a source into the air. Some examples of airborne sound are passing traffic, music or voices from an adjacent room, or the noise from machinery and aircraft. ====

====<span style="color: #282b2e; font-family: Arial,sans-serif;">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="color: #282b2e; font-family: Arial,sans-serif; font-size: 12pt;">Some practical sound control techniques that will improve the airborne sound transmission resistance of wall and floor-ceiling assemblies include:


 * <span style="color: #282b2e; font-family: Arial,sans-serif; font-size: 12pt;">Constructing partition walls with lightweight steel framing instead of wood studs.
 * <span style="color: #282b2e; font-family: Arial,sans-serif; font-size: 12pt;">Adding sound absorbing fiberglass insulation to wall and ceiling cavities.

<span style="color: #282b2e; font-family: Arial,sans-serif; font-size: 12pt;">Some practical sound control techniques that will reduce impact sound transmission through floor-ceiling assemblies include:


 * <span style="color: #282b2e; font-family: Arial,sans-serif; font-size: 12pt;">Installing thick carpeting and padding.
 * <span style="color: #282b2e; font-family: Arial,sans-serif; font-size: 12pt;">Structurally disconnecting floors and ceilings with resilient underlayments and isolated suspended ceiling systems.