Category: study by enoshmink team

Marcelia cinema

Test certificate for BBC studio egypt

Test report

 

Clint:

        BBC complex studios in cairo

Test date:

June 14, 2014

Location:

 

Test method

It is based on ASTM E 90 standard

Project discretion

This is hotel based in Cairo Egypt and unique place in Cairo  nile view in agouza

outside noise was  normally 85 db and when the rash hour begging  it measurers 88 db and it is vary hi noise

And that use technique of wall damping construction for sound isolation

 

 

 

 

 

 

 

 

 

Test object

  • Measure inside studio background noise
  • Measure outside studio ( street traffic )
  • Compere the measurements with the standard

 

Description of test

                      

Instruments:  sound level meter paa3 S/N 00380650

ACOUSTICAL calibrator B&K S/N 1897713

PAA3 SOFTWARE

HP I7     laptop

Test procedures 

Closing all the doors and start test with

 

SPL meter

RT 60

                          Space and time average

  • Average 6 meter from entrance door
  • Average 300 sec time

 

 

 

 

 

 

 

 

Test investigation

Audio booth

First test inside the door of the studio and location of test in center of the space and open the window

it measures

 

And measuring the back ground noise in the same place . with closing the window and Curtin

 

 

And measuring RT60

 

Second

Test outside lobby area (rooms)

Measuring in the rooms in third floor with dynamic range testing

 

Third

Test outside lobby area ( garage ) after lobby door to garage and with full loudspeaker power

Measuring that following

And RT60 for the air volume

 

 

 

And after closing the door of garage outside ( street)

Measuring as following ( with dynamic rage )

 

And that is show it noise from 100 hz to 1 khz related to traffic noise

 

The code and testing comparing

Project Design :: Hotel

Goal: To create an aesthetically pleasing and calming environment, which encourages guests to feel relaxed and comfortable so that they enjoy their stay and are more apt to return. To minimize noise from other guest rooms, the corridor and mechanical equipment.

  • Related Codes & Standards
    • Sound Transmission Class (STC)
    • Impact Insulation Class (IIC)
    • Universal Building Code/International Building Code (UBC/IBC)
  • Considerations
    • There are several issues that must be addressed concerning acoustics in a hotel project. These issues stem from the two types of sound that must be controlled: airborne sound and impact sound. A typical airborne sound is music or talking. A typical impact sound is the footfall sound of an upstairs guest.
    • There are two rating systems that compare the acoustic quality of various building assemblies. Both classify acoustical performance with a single number. In both cases, the higher the number, the better the sound isolation performance. Sound Transmission Class (STC) rates a partition’s resistance to airborne sound transfer.
    • The Uniform Building Code (UBC) contains requirements for sound isolation between dwelling units in Group R occupancy project (including hotels). However, these criteria are not universally enforced. UBC requires walls and floor/ceiling assemblies to have an STC rating of 50. The code also requires that floor/ceiling assemblies have an Impact Insulation Class rating of 50. *NOTE: Even if a particular municipality has not adopted this part of the code, it is still recognized as an industry standard minimum.
    • Resilient channel can be used to help improve the isolation quality of a wall. However, if artwork and/or headboards are mounted against the wall (as is often the case in a hotel), the effectiveness will be greatly diminished. Consider increasing the isolation through some other means (i.e., increased mass, increased air space, double or staggered stud walls, etc…).
    • All air-gaps and penetrations must be carefully controlled and sealed. Even a small air-gap can degrade the isolation integrity of an assembly.
    • The perimeter of the wall and any penetration must be sealed air-tight with a non-hardening acoustic sealant.
    • Avoid the installation of back-to-back penetrations (outlets, light switches, and phone jacks). Consider installing a putty pad to the back of all outlets in party walls.
    • Ideally, elevator shaft footings, floor pads, masonry shaft walls, elevator equipment mountings, etc. should be totally isolated from the building structure. Structure borne noise/vibration from elevator operation may be extremely annoying. Additionally, any penetration or air gap in or around the wall must be sealed airtight with a non-hardening acoustic sealant.
    • The building code (UBC) specifies that the entrance doors from interior corridors shall have an STC rating of 26 or higher. The higher the STC rating of the doors, the better the isolation. However, if the seal around and under the door is not maintained, selecting a high rated door is meaningless. Ideally, drop seals that seal to a threshold (not carpet) can be installed. An acoustically absorptive ceiling and carpet in the corridor will help to control the noise levels within the corridor.
    • The majority of noise concerns can be alleviated through proper space planning. Sensitive areas should not be located near potentially noisy areas. Potentially annoying sound transmission from floor to floor (for example, from a restroom or laundry facility above a bedroom) can be mitigated through the vertical mirror of spaces. Potentially noisy areas (such as elevators, vending rooms and laundry facilities) should not be adjacent to guest rooms.
    • Although the building code does not address plumbing noise, this issue can be a major source of noise complaints. Plumbing noise can be both airborne and structure borne. To reduce plumbing noise, pipes should be resiliently mounted, that is, adequately insulated from their supports. To further reduce plumbing noise, the pipes should be wrapped with pipe lagging material.
    • Any roof-mounted equipment should be analyzed for potential noise/vibration impact.
    • Consider the exterior noise impact to the guest rooms (such as a nearby airport or freeway). The majority of this noise is transmitted through the windows and P-Tac units. Upgrading these elements might be necessary.
    • Noise Criteria (NC) ratings can be used to specify the allowable background noise levels (not including activity noise from the occupants) within a given space. Recommended NC levels vary depending on the type of space and the listening requirements. The recommended NC level for a bedroom is NC 20-30. Most hotel air-conditioning systems produce noise levels well in excess of the recommendation. Additionally, HVAC noise can act as a masking system in hotel projects, raising the background noise level and thus reducing the awareness of transmitted noise. (NOTE: Obviously, this benefit only occurs when the system is on.) The equipment noise should not exceed NC 25-30 and the air noise of the HVAC system should not exceed NC 35.

Codes & Testing :: Sound Transmission Class (STC)

Code: STC rates a partition’s or material’s ability to block airborne sound.

Enforcement: Appendix Chapter 35 of the ’88 and ’91 UBC, Appendix Chapter 12, Division II of the ’94 and ’97 UBC will be contained in the forthcoming IBC. Although not all municipalities have adopted this appendix chapter, it is still recognized as an industry standard.

General Information: The Uniform Building Code (UBC) contains requirements for sound isolation for dwelling units in Group-R occupancies (including hotels, motels, apartments, condominiums, monasteries and convents).

UBC requirements for walls: STC rating of 50 (if tested in a laboratory) or 45 (if tested in the field*).

UBC requirements for floor/ceiling assemblies: STC ratings of 50 (if tested in a laboratory) or 45 (if tested in the field*).

* The field test evaluates the dwelling’s actual construction and includes all sound paths.

Definitions:

  • Sound Transmission Class rates a partition’s resistance to airborne sound transfer at the speech frequencies (125-4000 Hz). The higher the number, the better the isolation.

STC Strength: Classifies an assembly’s resistance to airborne sound transmission in a single number.

STC Weakness: This rating only assesses isolation in the speech frequencies and provides no evaluation of the barrier’s ability to block low frequency noise, such as the bass in music or the noise of some mechanical equipment.

Recommended Isolation Level
An assembly rated at STC 50 will satisfy the building code requirement, however, residents could still be subject to awareness, if not understanding, of loud speech. It is typically argued that luxury accommodations require a more stringent design goal (as much as 10dB better – STC 60). Regardless of what STC is selected, all air-gaps and penetrations must be carefully controlled and sealed. Even a small air-gap can degrade the isolation integrity of an assembly.

Codes & Testing :: Impact Insulation Class (IIC)

Code: IIC rates a floor/ceiling assembly’s ability to block impact sound.

Enforcement: Appendix Chapter 35 of the ’88 and ’91 UBC, Appendix Chapter 12, Division II of the ’94 and ’97 UBC will be contained in the forthcoming IBC. Although not all municipalities have adopted this appendix chapter, it is still recognized as an industry standard.

General Information: The Uniform Building Code (UBC) contains requirements for sound isolation for dwelling units in Group-R occupancies (including hotels, motels, apartments, condominiums, monasteries and convents).

UBC requirements for floor/ceiling assemblies: IIC ratings of 50 (if tested in a laboratory) or 45 (if tested in the field*).

* The field test evaluates the dwelling’s actual construction and includes all sound paths.

Definitions:

  • Impact Insulation Class (sometimes referred to as Impact Isolation Class) measures a floor/ceiling assembly’s resistance to the transmission of structure-borne or impact noise.

IIC Strength: Helps to rate structure-borne noise such as footfall, a chair dragging on the floor, or other realistic sounds in a single number.

IIC Weakness: Due to the nature of the testing procedure, almost any assembly with carpet will meet the IIC requirement. Meeting the IIC requirement does not ensure the control of footfall noise. Conversely, if an assembly does not meet the IIC requirement, it does not necessarily mean that there will be a footfall noise issue.

The tapping machine frequently used for this test is not designed to simulate any one type of impact, such as a male or female footsteps, nor to simulate the weight of a human walker. Thus the subjectively annoying creak or boom generated by human footfalls on a limber floor assembly may not be adequately evaluated by this method (American Society for Testing and Materials – ASTM, E 1007, 5.2).

Recommended Isolation Level
An IIC rating of 50 will satisfy the building code requirements. As with STC, it is typically argued that luxury accommodations require a more stringent design goal. Bare in mind, some floor assemblies rated as high as IIC 70 could still transfer noticeable footfall noise.

Recommended Isolation Level
An IIC rating of 50 will satisfy the building code requirements. As with STC, it is typically argued that luxury accommodations require a more stringent design goal. Bare in mind, some floor assemblies rated as high as IIC 70 could still transfer noticeable footfall noise.

ANSI  (recommendation) .

Hotels/Motels
          Individual rooms or suites 40-45 (db)
          Meeting/banquet rooms 40-45 (db)
          Halls, corridors, lobbies 45-50 (db)
          Service/support areas 60-65 (db)

 

And for the clubs

The noise levels in clubs ranges between  95-98 dB(A) region

Ground type., the exposure times and frequency of exposure and the proportion of attenders vs. non-attenders . According to all the previous factors a test must be  retake Loud speakers will be relocated  according to the wind direction , to reach the standards levels .

 

 

Conclusion

  • All the door must retreated with new gasket
  • Must adding a threshold for main door and garage
  • All partitioning tested is meet E90 STARNDRD
  • Traffic and train noise totally sound isolated

*The test result  apply to the time of test (from 5 pm to 10 pm ) we will not be responsible for any other test done out of the above time frame.

 

This study made under American standard test method  

Dr. Ibrahim Elnoshokaty.               

Acoustical consultant                   

 

Eng. Eslam Youssef                        Eng. Mohamed hamdi

  R & D engineer                       Test and measurement

                                                     Engineer

 

 

 

improve audio streaming using sharedin audio streaming codec and player

 

introduction

A one-way audio transmission over a data network. It is widely used to listen to audio clips and radio from the Internet on computers, tablets and smartphones. In addition, computers at home are commonly set up to stream a user’s music collection to a digital media hub connected to a stereo or 5.1 . Listening to momentary blips in music or a conversation is annoying, and the only way to compensate for that over an erratic network such as the Internet is to get some of the audio data into the computer before you start listening to it. In streaming audio, both the client and server cooperate for uninterrupted sound. The client side stores a few seconds of sound in a buffer before it starts sending it to the speakers. Throughout the session, it continues to receive audio data ahead of time.

High-resolution audio

The industry has been transformed by digital downloads from sites such as iTunes, marking a shift away from physical media like vinyl, tapes and CDs. Formats including MP3 and AAC make it easy to buy, listen and store our tunes. With regards to sound quality, however, these formats just don’t cut the mustard. The use of lossy compression means that data is lost in the encoding process, which means resolution is sacrificed for the sake of convenience and smaller file sizes.

encoding process

Lossy codecs: Many of the more popular codecs in the software world are lossy, meaning that they reduce quality by some amount in order to achieve compression. Often, this type of compression is virtually indistinguishable from the original uncompressed sound or images, depending on the codec and the settings used.[4] Smaller data sets ease the strain on relatively expensive storage sub-systems such as non-volatile memory and hard disk, as well as write-once-read-many formats such as CD-ROMDVD andBlu-ray Disc. Lower data rates also reduce cost and improve performance when the data is transmitted.

Lossless codecs: There are also many lossless codecs which are typically used for archiving data in a compressed form while retaining all of the information present in the original stream. If preserving the original quality of the stream is more important than eliminating the correspondingly larger data sizes, lossless codecs are preferred. This is especially true if the data is to undergo further processing (for example editing) in which case the repeated application of processing (encoding and decoding) on lossy codecs will degrade the quality of the resulting data such that it is no longer identifiable (  audibly or both). Using more than one codec or encoding scheme successively can also degrade quality significantly. The decreasing cost of storage capacity and network bandwidth has a tendency to reduce the need for lossy codecs for some media.

achievement of lossless codec’s and bandwidth

It’s basically a protocol allowing media to be streamed from any bog-standard HTTP server whilst keeping some of the functionality provided by dedicated media servers. For example; HLS allows you to adjust the video quality in real-time, based on the bandwidth available to the client.

It can be used for ‘Live’ broadcasts and Video on Demand, and it’s file based nature means that it plays really well with Content Distribution Networks. Once prepared for delivery, the content needed to provide a stream is static (though a ‘Live’ stream, but it’s very nature, won’t be), so the stream can be served from any HTTP(S) server.

Great news for those in the creative industry – HLS also supports (incredibly) basic DRM in the form of AES-128 encryption. We won’t be covering that though as it’s outside the scope of this piece

The HLS Output File Structure and Codec

HLS is a truly adaptive bitrate technology. When audio is encoded to HLS multiple files are created for different bandwidths and different resolutions. The files are encoded using the mpg2_ts codec. The streams are mapped to the client in real time using an .M3u8 index file based on screen size and available bandwidth.

.1-1

 

 

 

To make the system scalable and adaptable to the bandwidth of the network, the video flow is coded in different qualities. Thus, depending on the bandwidth and transfer network speed, the video will play at different qualities.

To implement this, the system must encode the video in different qualities and generate an index file that contains the locations of the different quality levels.

The client software internally manages the different qualities, making requests to the highest possible quality within the bandwidth of the network. Thus always play the video the highest possible quality, viewing lower quality on 3G networks and highest quality in Wi-Fi broadband.

 

sharedin Live Streaming

consists of three parts: the server component, the distribution component, and the client software.

 1-2

1- server component

The server requires a media encoder, which can be off-the-shelf hardware, and a way to break the encoded media into segments and save them as files, which can either be software

1-1 Media Encoder

Encoding should be set to a format supported by the client device,

1-2 Stream Segmenter

sharedin stream segmenter is software can reads the Transport Stream from the local network and divides it into a series of small media files of equal duration. Even though each segment is in a separate file, audio files are made from a continuous stream which can be reconstructed seamlessly. also encrypt each media segment and create a key file

1-3 File Segmenter

The segmenter also creates an index file containing references to the individual media files. Each time the segmenter completes a new media file, the index file is updated of equal length

 

 

 

 

2- Distribution Components

The distribution system is a web server or a web caching system that delivers the media files and index files to the client over HTTP. No custom server modules are required to deliver the content, and typically very little configuration is needed on the web server.

 

sharedin Client Component

sharedin begins by fetching the index file, based on a URL identifying the stream. The index file in turn specifies the location of the available media files, decryption keys, and any alternate streams available. For the selected stream, sharedin client downloads each available media file in sequence. Each file contains a consecutive segment of the stream. Once it has a sufficient amount of data downloaded, the client begins presenting the reassembled stream to the user.sharedin client is responsible for fetching any decryption keys, authenticating or presenting a user interface to allow authentication, and decrypting media files as needed.This process continues until the client encounters the #EXT-X-ENDLIST tag in the index file. If no #EXT-X-ENDLIST tag is present, the index file is part of an ongoing broadcast. During ongoing broadcasts, the client loads a new version of the index file periodically. sharedin client looks for new media files and encryption keys in the updated index and adds these URLs to its queue.

 

 

 

Protection against errors

In this case is generated a different flows with the same quality video and locations are listed in the index file.

The management of all files is done from the client, so that if it fails the first flow, use the next and successively.

Encryption with Encoding.com

content can be easily encrypted. Currently sharedin supports AES-128 encryption using 16-octet keys. There are three ways in which encryption can be applied: using an existing key, using a randomly generated key, or using a new key that’s generated for every X number of video segments. The more video segments that have unique encyrption, the greater the overhead and the less the performance. Keys can be served over SSL for an added layer of encryption.

Device and OS Compatibility

All iOS devices running 3.0 and later support sharedin

Android

Android 4.0 (Ice Cream Sandwich).

Android 4.1+ (Jelly Bean)

Android 4.4+ (Kit Kat)

Most new top-of-the-line Androids now support High Profile level

Desktop shardin Support

all  web browser has native support

OTT- Over-the-top Video Devices

Most current OTT devices support shardin tech. Like HLS, OTT devices prefer transmitting data over HTTP, which makes the two technologies a great fit as sharedin tech is also delivered via HTTP. Some of the top OTT devices with support for sharedin tech are as follows: .Apple TV

  • Roku 3
  • D-Link MovieNite Plus
  • Boxee Cloud DVR

concolusion

sharedin tech are made for internet radio to get good quality of audio signal without cutting or buffering at all bandwidth from gsm mobile traditional bandwidth to broadband and that tech has alot for development and enhancement and the development of sharedin tech  only in the stream sigmenter and the Clint player that all not success without HLS technology . sharedin add new stone at the pyramid of HLS

presnted by

Dr. ibrahm noshokaty

april 2015

najaf Auditorium project IRAQ

 

MTI

400 Bed General Hospitals Project
 
Enoshmink Technology & Media Services
12/19/2013
 

 

 

Project Acoustical Design :: Auditorium/Theater

Goal: To properly balance absorption and reflection to provide a favorable acoustical environment. One must address both the need to hear and understand speech, and the desire to have a pleasant space for music.

  • Tips/Considerations
    • Recommended reverberation time is 1.0-1.5 seconds (might be higher for some auditoriums).
    • Although the seating area will provide absorption, thereby reducing the reverberation time, you will most likely need to add absorptive materials to the other surfaces within the space.
    • It is vital to control the reflections from the back wall. If you don’t control them, the presentation could reflect off the back wall and “slap back” to the presenter(s). This won’t necessarily impact the audience, but could be disastrous and distracting for the people on stage. Because of this, it’s usually necessary to treat the back wall with an absorptive material. A concave back wall could compound this problem. If you can’t avoid a concave back wall, it’s imperative that it be treated with absorptive material.
    • Splay or use irregular surfaces on the walls to avoid flutter echoes. Parallel reflective surfaces can allow sound to “ricochet” back and forth between the surfaces. This potentially annoying condition is referred to as standing wave or flutter echo. It is avoided by constructing non-parallel surfaces or by adding absorptive materials to the surface(s).
    • Consider faceting the ceiling to help with sound dispersion.
    • Control the reverberation time on the stage. Ideally, the reverberation time in the stage area should be the same as in the house. Since the stage area might have a higher ceiling than the rest of the auditorium, more absorptive materials might be required in this area. Frequently, the back wall of the stage, and possibly one or two of the side walls, is treated with an acoustically absorptive material, typically black in color.
    • Remember the space will be less absorptive when only half full, since the audience itself is absorptive. By using absorptive seating areas, the reverberation time will remain more consistent regardless of the audience size.
    • Noise from the lobby area can be disruptive. Be sure openings such as doorways are properly sealed. Consider a vestibule door system.
    • Persons seated deep under a balcony might experience auditory distortion. To avoid this, the balcony should be no deeper than twice its height. Ideally, the balcony should not be any deeper than its height.
    • Even if everything else is controlled perfectly, the space might not be usable if the background noise (e.g. HVAC system) is too loud. To help protect your design, the NC level should not exceed 20 to 35. When specifying NC, specify an actual rating, such as NC 20, rather than a range, such as NC 20-30. Although specifying a lower number will ensure minimal background noise, it might be cost prohibitive to achieve. Be realistic about the amount of acceptable noise and the project’s budget when specifying an NC level.
    • Beware of potential outdoor noise impacting your space. For example, is your location near a flight path, a railroad or freeway? If so, you might have to pay critical attention to blocking this noise. To do so effectively, you must address not only the STC or isolation quality of the exterior wall, but also for the possibly weaker building elements, such as the

Auditorium sound transmission loss:

 

Wall 1 and 3

 

Wall 2 and 4

 

Ceiling

Wall sound Isolation Thickness ( wall damping concept ):

Recommended ANSI Levels for Large auditoriums, (for very good speech articulation) :  35   db

Used material :    Rock wool

Material density:   80    m3/Kg

SPL:   85   db

 

 

 

 

 

 

 

WALL NAME

   THICKNESS

 

Wall 1                                                                       

 

0.0120975198718746  m

 

Wall 2

0.0217294161921501  m

 

Wall 3

0.0120975198718746  m

 

Wall 4

0.0217294161921501  m

 

Ceiling

0.00532148967971023  m

 

 

 

 

 

 

 

 

 

 

 

 

2- Reverberation time before sound treatment calc

 

Reverberation time of the auditorium before sound treatment

 

Frequencies (HZ)

 

 

125

 

250

 

500

 

1000

 

2000

 

4000

 

RT 60

 

 

1.79830407258774

 

2.37372022535858

 

1.11229061289745

 

0.829339416874118

 

0.7816360567047

 

 0.764687873972774

 

 

Length:     24.5     m

Width:       13.64     m

Height:      6     m

Volume:   2005.08    m3

 

 

 

  

 

  Wall

   

 

 

 

 

Material  

     
 

Front Wall

   

gypsum_board

     
 

Back Wall

      gypsum_board      
 

Right Wall

     gypsum_board      
 

Left Wall

     gypsum_board      
 

Ceiling

     Enosh      
 

Floor

      floors,wooden                                                                                            

 

 

 

 

 

 

 

 

 

 

3-Reverberation time after sound treatment calc

 

Enosh Ceiling:

 

Length:     < enosh_ceiling>           m

Width:       9             m

Material:   1”       m     

 

Eonsh pallet:

 

Number: 10

Area:  37.5      m2

Material: 2”

 

 

 

 

 

 

 

 

RT 60 at different frequencies (after adding enosh materials):

 

 

 

Frequencies (HZ)

 

 

125

 

250

 

500

 

1000

 

2000

 

4000

 

RT 60

 

 

1.16485073560508

 

0.688448147242969

 

0.383563617180037

 

0.323910429879985

 

0.326120568218462

 

 0.329313120258735

 

4-Critical area after sound treatment  

 

 

 

 

5- calc of Standing Waves:

 

 

Frequency Length Width Height    
F1 7 12.5733137829912 28.5833333333333    
F2 14 25.1466275659824 57.1666666666667    
F3 21 37.7199413489736 85.75    
F4 28 50.2932551319648 114.333333333333    
F5 35 62.866568914956 142.916666666667    
F6 42 75.4398826979472 171.5    
F7 49 88.0131964809384 200.083333333333    
F8 56 100.58651026393 228.666666666667    
F9 63 113.159824046921 257.25    
F10 70 125.733137829912 285.833333333333    

 

 

 

 

 

 

 

 

 

 

 

6- the shape of the diffuser to remove standing wave 

Diffusers:

Length: 1.5

Width:  0.3

Depth: 

   0.0571666666666667                  0.228666666666667                0.228666666666667

   0.0571666666666667                  0

 

The application of the diffuser will be in the wall panel

                    

 

                                        

7-Codes & Testing :: Sound Transmission Class (STC)

Code: STC rates a partition’s or material’s ability to block airborne sound.

Enforcement: Appendix Chapter 35 of the ’88 and ’91 UBC, Appendix Chapter 12, Division II of the ’94 and ’97 UBC will be contained in the forthcoming IBC. Although not all municipalities have adopted this appendix chapter, it is still recognized as an industry standard.

General Information: The Uniform Building Code (UBC) contains requirements for sound isolation for dwelling units in Group-R occupancies (including hotels, motels, apartments, condominiums, monasteries and convents).

UBC requirements for walls: STC rating of 50 (if tested in a laboratory) or 45 (if tested in the field*).

UBC requirements for floor/ceiling assemblies: STC ratings of 50 (if tested in a laboratory) or 45 (if tested in the field*).

* The field test evaluates the dwelling’s actual construction and includes all sound paths.

Definitions:

  • Sound Transmission Class rates a partition’s resistance to airborne sound transfer at the speech frequencies (125-4000 Hz). The higher the number, the better the isolation.

STC Strength: Classifies an assembly’s resistance to airborne sound transmission in a single number.

STC Weakness: This rating only assesses isolation in the speech frequencies and provides no evaluation of the barrier’s ability to block low frequency noise, such as the bass in music or the noise of some mechanical equipment.

Recommended Isolation Level
An assembly rated at STC 50 will satisfy the building code requirement, however, residents could still be subject to awareness, if not understanding, of loud speech. It is typically argued that luxury accommodations require a more stringent design goal (as much as 10dB better – STC 60). Regardless of what STC is selected, all air-gaps and penetrations must be carefully controlled and sealed. Even a small air-gap can degrade the isolation integrity of an assembly.

 


 

8-Codes & Testing :: Reverberation Time (RT60)

Test: RT60 measures the reverberance within a room.

Related Code: RT60 is soon to be adopted under ADA for classroom acoustic criteria.

General Information: Reverberation Time is the time required, in seconds, for the average sound pressure level in a room to decrease 60 decibels after a source stops generating sound. This test is standard on certain projects, such as “THX” movie theaters and various government buildings. Normally, in the design phase, you must demonstrate (through calculations) that a space will achieve the stipulated reverberation time. Often times, measurements are required to verify results.

Strength: Because RT60 is void of variables, unlike many other tests, it is straightforward and clear-cut.

Weakness: RT60 does not account for problematic and potentially annoying reflections. Often times, there is still a need for expert analysis.

 

 

 

9-Codes & Testing :: Noise Criteria (NC)

Code: This industry standard (also an ANSI standard) usually pertains to HVAC or mechanical noise impact.

Enforcement: This standard is often required for certain certifications (such as government medical facilities) or included in client specifications/standards (for example, some companies have NC standards that their buildings must meet).

General Information: An NC level is a standard that describes the relative loudness of a space, examining a range of frequencies (rather than simply recording the decibel level). This level illustrates the extent to which noise interferes with speech intelligibility. NC should be considered for any project where excessive noise would be irritating to the users, especially where speech intelligibility is important. There are a few spaces where speech intelligibility is absolutely crucial, including:

For some areas, such as machine shops or kitchens, it is not essential to maintain a particularly low NC level.

NC Level Strength: It is important for design professionals to specify NC ratings to protect their designs (within reason – specifying an acceptable NC level does not have to be a burden on the budget). Doing so speaks to your reputation as a responsible architect or designer and limits your liability.

NC Level Weakness: NC does not account for sound at very low frequencies. In spite of numerous efforts to establish a widely accepted, useful, single-number rating method for evaluating noise in a structure, a variety of techniques exist today. The vast majority of acoustic professionals use the NC standard, but it is still important to be aware of the other acceptable methods that do account for low frequency levels, including (but not limited to):

  • Room Criteria (RC) measures background sound in a building over the frequency range 16 Hz to 4000 Hz. This rating system requires two steps: determining the mid-frequency average level and determining the perceived balance between high and low frequency sound. To view the recommended ANSI levels for room criteria for various activity areas.
  • Balanced Noise Criteria (NCB) is based on the ANSI threshold of audibility for pure-tones and is defined as the range of audibility for continuous sound in a specified field from 16 Hz to 8000 Hz.

 

Conclusion

1-   Wall damping system theckinss 14 to 15cm

2- Wall treatment using acoustics panel NRC UP to 1.15

3- Ceiling treatment using acoustics panel NRC up to .80

4-  Floor treatment using bright surface to balance the RT of room

5- Standing wave are detect by 10 frequency

6- Must diffuse all wall by two thickness panel

7- theater seats must be foam injection not

sponge     

this stady according to American standard

ASTM E90-2009″ Standard Test Method for Laboratory Measurement

Of Airborne Sound Transmission loss of Building Partitions”

ASTM E4I3-2004″ Classification for Rating Sound insulation”

Dr. Ibrahim elnoshokaty

Member acoustical society of America

Member acoustical society of Egypt

 

 

 

                              

 

 

           

 

 

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