Acoustics

-Transverse: vibration at right angle to direction of travel of wave.
Notes: -In the first video we can see how is the sound wave travel in the air, in various kind of situations, the graphics of sound waves are considerably different, as to the speed of the waves and the highest point that they can achieve, and this depends of the materials that produce the sound together. -In the second video, it explain to us that exist three different sources of sound give the voice the musical instruments: vibrant columns of air as the wood wins, vibrant surfaces such drums head and cymbals, and vibrant strings that is all of the string section. Each sound in our environment originated in some object that vibrates. In this video we can see how the sound is produce, and the three auditory effects of musical sounds (loudness, pitch and quality) and how is measured through of various examples.  -In the third video said that //"optimal acoustics can be created by choosing the right amount and the right placement of absorption material"//. A example is: improving the acoustics of a place can improve teaching and learning in a classroom.

Concepts related to acoustics:

1) About Sound: 

2) Room acoustics descriptors:

-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.

-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.

-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.

-Spatial decay:  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: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">3) Sound insulation:

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Room-to-room insulation: <span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> How to avoid unwanted sounds from adjacent rooms.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-One-way sound insulation: <span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> Suspended acoustic ceilings help to avoid noise coming from installations.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Vertical airborne sound insulation: <span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> Airborne sound insulation may relate to sounds generated in both the room below and the room above.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Impact sound insulation: <span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> A suspended ceiling system can be used to improve the impact sound insulation and therefore reduce the impact sound level.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">4) Room Acoustic Design

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Different acoustic room types: <span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> The way sound behaves and affect the people in the room depends heavily on the room geometries and placement of absorption material. Find out what acoustic room type you are working on.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Choosing the right sound absorption: <span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;">Using absorption class A means that less material is needed and quality of teaching, working and healing is optimized.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Acoustic design with wall panels and acoustical islands <span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;">: A fully covered absorbing ceiling is the preferred solution for placement of sound absorption material. Sometimes, the design might require additional or alternative solutions.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">5) Room acoustic planning <span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;">: It is vital to clearly specify your requirements for room acoustic quality early on in the building process.

<span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;">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. At the moment, building standards etc. almost exclusively focus on the room acoustic descriptor reverberation time, associated with the room’s reverberance. It is important to be aware that room acoustic comfort does not just mean a particular reverberation time.

<span style="font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> 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. .. In order not to constantly have to reinvent the wheel and in order to formulate the ideal requirements for you and your users, it can be a good idea to draw up your own sound policy.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">6) Acoustic comfort:

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-The reverberation time depends not only on absorption, but also furnishings, the location of the absorbers and the shape of the room

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-The more absorption in the room, the lower the sound level

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-By only assessing the reverberation time, you ignore acoustic information that is important for subjective perception

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Despite having the same reverberation time, rooms can subjectively be perceived differently

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-In open-plan rooms, descriptors linked to the sound's propagation are more important than reverberation time.

<span style="color: #00b0f0; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">7) How to improve acoustics: <span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">Simply speaking, any sound that is unwanted, or in excess, is "noise." CertainTeed Building Science investigates sound paths to understand sound's sources and modes of transmission.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">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.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">Some practical sound control techniques that will improve the airborne sound transmission resistance of wall and floor-ceiling assemblies include:

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> -Constructing partition walls with lightweight steel framing instead of wood studs.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> -Adding sound absorbing fiberglass insulation to wall and ceiling cavities.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> -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="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> -Structurally breaking the tie between finished drywall surfaces and wood framing using resilient channel or acoustically engineered gypsum board.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">Some practical sound control techniques that will reduce impact sound transmission through floor-ceiling assemblies include:

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> -Installing thick carpeting and padding.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;"> -Structurally disconnecting floors and ceilings with resilient underlayments and isolated suspended ceiling systems.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Isolating plumbing and electrical conduits from structures with resilient pads and hangers.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">Improve the acoustical performance of room spaces using solutions that include:

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Suspending sound absorbing acoustical ceiling tile systems.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Installing carpeting in open plan spaces to cover hard surfaces.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 18.6667px;">-Installing acoustically absorptive wall partitions and coverings to dampen sound energy.

<span style="display: block; height: 1px; left: -40px; overflow: hidden; position: absolute; text-align: justify; text-indent: -18pt; top: 250px; width: 1px;"><span style="color: black; font-family: Symbol; font-size: 14.0pt; line-height: 115%; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; mso-themecolor: text1;"> Speed: is the distance travelled in unit time (m/s) <span style="display: block; height: 1px; left: -40px; overflow: hidden; position: absolute; text-align: justify; text-indent: -18pt; top: 250px; width: 1px;"><span style="color: black; font-family: Symbol; font-size: 14.0pt; line-height: 115%; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; mso-themecolor: text1;"> Frequency: is the number of complete waves in one second. This is measured in Hertz (Hz). <span style="display: block; height: 1px; left: -40px; overflow: hidden; position: absolute; text-align: justify; text-indent: -18pt; top: 250px; width: 1px;"><span style="color: black; font-family: Symbol; font-size: 14.0pt; line-height: 115%; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; mso-themecolor: text1;"> Wavelength: Distance between matching points on the wave. This is sometimes called Lambda (λ) and it is measured in metres (m) <span style="display: block; height: 1px; left: -40px; overflow: hidden; position: absolute; text-align: justify; text-indent: -18pt; top: 250px; width: 1px;"><span style="color: black; font-family: Symbol; font-size: 14.0pt; line-height: 115%; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; mso-themecolor: text1;"> Longitudinal: longitudinal waves vibrate parallel to the direction of travel of the wave. Sound waves are longitudinal. <span style="display: block; height: 1px; left: -40px; overflow: hidden; position: absolute; text-align: justify; text-indent: -18pt; top: 250px; width: 1px;"><span style="color: black; font-family: Symbol; font-size: 14.0pt; line-height: 115%; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; mso-themecolor: text1;"> Transverse: vibration at right angle to direction of travel of wave.