Acoustics

Definitions:

1) Speed:


 * rush: move fast; "He rushed down the hall to receive his guests"; "The cars raced down the street"
 * distance travelled per unit time
 * accelerate: move faster; "The car accelerated"
 * a rate (usually rapid) at which something happens; "the project advanced with gratifying speed"
 * travel rapidly: move very fast; "The runner zipped past us at breakneck speed"
 * changing location rapidly
 * travel at an excessive or illegal velocity; "I got a ticket for speeding"
 * focal ratio: the ratio of the focal length to the diameter of a (camera) lens system
 * amphetamine: a central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression

2) Frequency:


 * the number of occurrences within a given time period; "the frequency of modulation was 40 cycles per second"; "the frequency of his seizures increased as he grew older"
 * the ratio of the number of observations in a statistical category to the total number of observations

3) Wavelength:


 * the distance (measured in the direction of propagation) between two points in the same phase in consecutive cycles of a wave
 * a shared orientation leading to mutual understanding; "they are on the same wavelength"

4) Longitudinal:


 * of or relating to lines of longitude; "longitudinal reckoning by the navigator"
 * over an extended time; "a longitudinal study of twins"

5) Transverse:


 * cross(a): extending or lying across; in a crosswise direction; at right angles to the long axis; "cross members should be all steel"; "from the transverse hall the stairway ascends gracefully"; "transversal vibrations"; "transverse colon"

__**How sound is created**__ (Video)

Sound is created when the following criteria are satisfied. 1.An object vibrates. 2.The object must be in contact with the air. 3.The air must be in contact with the listener. 4.The air contact between the source and listener must be continuous, without a vacuum gap.

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.
 * Reverberance**

=**What are room acoustics?**= 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 field of building acoustics covers sound insulation too, where the route that the sound takes from the room to other areas is included. **Room Acoustic Comfort – a natural part of the indoor environment**

A room and its acoustic quality should be a support for people and the activities in which they are involved. To create the correct acoustic conditions is to create Room Acoustic Comfort™. Room acoustic comfort is an important element of the sound environment concept and this, along with light, air and perception of the room, is in turn a natural component of the total indoor environment.

**What do you as an architect need to consider regarding Room Acoustic Comfort™?**

In many environments where people are present and communicate, high sound levels are perceived as one of the most disturbing factors. High noise levels have a negative effect on us and affect health, communication, safety, economy (effectiveness/productivity), learning and general wellbeing. It is therefore important that you as an architect remember that room acoustic comfort does not only involve a certain reverberation time. To reduce sound levels, it is important to consider other descriptors that are directly linked to sound levels, such as Strength (G). **The reverberation time is decided by:** - Added absorption and how it is placed - The quantity and placing of sound-scattering objects such as furniture, shelves etc. - The size and shape of the room **The sound level is essentially determined by:** - The amount of absorption **Clarity of speech is essentially determined by:** - Early sound reflections in relation to late sound reflections - Background noise Room Acoustic Comfort™ (RAC™) means that, when performing an evaluation of room acoustics, it is important to take into account different types of rooms and what people do there. Give priority to the different acoustic properties such as reverberance, speech clarity and sound level, depending on what the room is used for. For example:
 * Sound level reduction will be most important in a kindergarten.


 * In a music room, the response of the room in the form of reverberance can be the most important aspect.


 * In a teaching situation, it is important to give priority both to speech clarity and to reduction of sound level.


 * In an open office landscape, it is essential that the sound propagation is restricted in order to minimise disturbance, mainly between different work groups. It is important that the sound level falls quickly with distance.

=**What must you as an architect do to achieve Room Acoustic Comfort™?**=



In many of the commonly occurring types of rooms that we talk about here, a sound-absorbing ceiling is a practical aid for achieving Room Acoustic Comfort™ (RAC™). The ceiling’s sound-absorbing properties are described in sound absorption classes (A-E) in an international standard. Class A is the highest level of sound absorption. **The ceiling’s effect on different acoustic descriptors:** **Reverberation time:** The sound-absorbing ceiling will interact with the sound-dispersing (scattering) furnishings in the room. The more sound-dispersing (scattering) objects there are, the greater the benefit of the ceiling. In a sparsely furnished room, the reverberation time can be long as the sound energy lingers between sound-reflecting walls.

**Sound level:** The sound level that is constantly generated in the room will, on the other hand, be effectively dealt with by the ceiling and be less dependent on sound-dispersing (scattering) objects. A sound absorption class A product provides the most effective decrease of the sound level.

**Speech clarity:** Suspended ceilings have a positive effect on speech clarity by reducing the reverberance in the room. A good, effective, sound-absorbing ceiling contributes to a good relation between early and late sound reflections in such a way as to benefit speech clarity.