Republic of the PhilippinesUniversity of Southeastern PhilippinesCOLLEGE OF ENGINEERINGObrero Campus, Davao City

BROADCAST ENGINEERING AND APPLIED ACOUSTICS

Architectural Acoustics and Sound System:Corporate Auditorium

Submitted to:Engr. Joey Dela Cruz

Submitted By:Cedric D. ConolJoannacel A. Paraiso

March 2015

Introduction

Architectural acoustics (also known as room acoustics and building acoustics) is the science and engineering of achieving a good sound within a building and is a branch of acoustical engineering. The first application of modern scientific methods to architectural acoustics was carried out by Wallace Sabine in the Fogg Museum lecture room who then applied his new found knowledge to the design of Symphony Hall, Boston.Architectural acoustics can be about achieving good speech intelligibility in a theatre, restaurant or railway station, enhancing the quality of music in a concert hall or recording studio, or suppressing noise to make offices and homes more productive and pleasant places to work and live in. Architectural acoustic design is usually done by acoustic consultants.In this document, a Corporate Auditorium is designed to meet architectural acoustics standards. A Corporate Auditorium is also an audiovisual room. Audiovisual (AV) means possessing both a sound and a visual component, such as slide-tape presentations, films, television programs, church services and live theater productions.Business presentations are also often audiovisual. In a typical presentation, the presenter provides the audio by speaking, and supplements it with a series of images projected onto a screen, either from a slide projector, or from a computer connected to a projector using presentation software.

Design Background

This document presents an architectural acoustic design of a Corporate Auditorium. The 41, 040 square feet - facility that is to be established has a total seating capacity of two-hundred and twenty (220) audiences.The corporate auditorium is designed to be used for business presentations where marketing officers, businessmen and CEOs can present their work and agendas.

Design Concept

I. Room Acoustics

General architectural factors that affect the rooms acoustics are greatly considered.

a.) Room Design and Layout

The proposed design is shown below. It is large enough to cater up to 500 audiences. The walls and the floor are both covered by sound absorbing materials. The walls have sound absorbing panels and is layered to absorb noise. The floor is made of a fabric, which is also known to absorb noise.The ceiling is high enough not to cause disturbing sound reflections but low enough to use lights efficiently. Ceiling is also layered according to the elevation of the seats.b.) Floor AreaThe figure below is 100 by 410.4 meters, which sets the total floor area equal to 41, 040 square meters.c.) VolumeThe ceiling is varying in height because of the elevation, it has an average of 5 meters in height, multiplying this value to the floor area gives us the room volume of 2250 cubic meters.

Architectural Specifications

ItemValueUnit

Room Width100Feet

Room Length410.4Feet

Room Height12Feet

Room Area41040sq. ft.

Room Volume492480cu. ft.

Lower Floor Inclination15degrees

Upper Floor Inclination40degrees

Number of Seat Rows10rows

Number of Seat Columns22columns

Total Number of Seats220seats

Stage Width75Feet

Stage Length55Feet

Stage Height4Feet

II. Acoustics ConsiderationsThe most important aspect to consider in this design is the audience, the room must properly treat sound waves to provide high fidelity sound right in the ear of every single audience.

a.) Seat AreaThe auditorium allocates about 8 square meter of area per audience. If we take into account the total seating capacity of the auditorium, 220 audience, the total audience area would be 1760 square feet.

b.) Sound AbsorptionAcousticabsorptionrefers to a material ' structure ' or object taking insound energywhensound wavesare encountered, as opposed toreflectingthe energy. Part of the absorbed energy is transformed intoheatand part is transmitted. The energy transformed into heat is said to have been 'lost'. When sound from a loudspeaker collides with the walls of a room part of the sound's energy isreflectedand part is absorbed into the walls. As the waves travel through the wall they deform the material thereof (just like they deformed the air before). This deformation has mechanical losses which convert part of the sound energy into heat through acoustic attenuation, mostly due to the wall'sviscosity. The same attenuating mechanics apply for the air and any othermediumthrough which sound travels. The fraction of sound absorbed is governed by theacoustic impedancesof both media and is a function of frequency and the incident angle.Size and shape can influence the sound wave's behavior if they interact with its wavelength, giving rise towave phenomenasuch asstanding wavesanddiffraction.Acoustic absorption is of particular interest insoundproofing. Soundproofing aims to absorb as much sound energy (often in particular frequencies) as possible converting it into heat or transmitting it away from a certain location.In general, soft ' pliable ' porous materials, like cloths, serve as good acoustic insulators - absorbing most sound; whereas dense ' hard ' impenetrable materials, like metals, reflect most.How well a room absorbs sound is quantified by the effective absorption area of the walls, also named total absorption area. This is calculated using its dimensions and the absorption coefficientsof the walls.The total absorption is expressed inSabinand is useful in, for instance, determining thereverberation timeof the auditorium. At = 0.049 x V/TrLet Tr = 1.5sAt = 0.049 x 492,480/1.5At = 16,088 sabins

Shown in the figure below the effect of putting sound absorbers in the auditorium. Figure (a) is the original sound wave reflection pattern, concrete walls are not good sound absorbers and there therefore reflect them. After putting white paintable acoustical tile, carpet and drapes, the sound are being absorbed and reflects lesser. Sound reflection is tackled in the next section. The figure above shows the picture of a white paintable acoustical tile.

c.) Sound Reflection

When a longitudinalsound wavestrikes a flat surface, sound is reflected in a coherent manner provided that the dimension of the reflective surface is large compared to the wavelength of the sound. Note that audible sound has a very wide frequency range (from 20 to about 17000Hz), and thus a very wide range of wavelengths (from about 20mm to 17m). As a result, the overall nature of the reflection varies according to the texture and structure of the surface. For example, porous materials will absorb some energy, and rough materials (where rough is relative to the wavelength) tend to reflect in many directionsto scatter the energy, rather than to reflect it coherently. This leads into the field ofarchitectural acoustics, because the nature of these reflections is critical to the auditory feel of a space. In the theory of exteriornoise mitigation, reflective surface size mildly detracts from the concept of anoise barrierby reflecting some of the sound into the opposite direction.

Shown above is an acoustical phenomena, it shows the effect of the shape of the ceiling to the direction of sound reflection.

d.) Reverberation

Reverberation, in psychoacoustics and acoustics, is the persistence of sound after a sound is produced. A reverberation, or reverb, is created when a sound or signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space which could include furniture and people, and air. This is most noticeable when the sound source stops but the reflections continue, decreasing in amplitude, until they reach zero amplitude. Reverberation is frequency dependent. The length of the decay, or reverberation time, receives special consideration in the architectural design of spaces which need to have specific reverberation times to achieve optimum performance for their intended activity. In comparison to a distinct echo that is a minimum of 50 to 100 ms after the initial sound, reverberation is the occurrence of reflections that arrive in less than approximately 50ms. As time passes, the amplitude of the reflections is reduced until it is reduced to zero. Reverberation is not limited to indoor spaces as it exists in forests and other outdoor environments where reflection exists.

Reverberation time given, Tr:For 500 Hz:Tr = k x V/Atk = 0.049V= 492, 480 ft3At =12, 438 ft2Tr = 0.049 x 492,480/12,438Tr = 1.92 s

Sabins design = 16,088Sabins given = 12,538Sabins needed = 16,088-12,538 = 3,550Translate to Acoustical tile

= sabins/0.67= 3,550/0.67= 5,299 square feetRecompute Tr:For 500 Hz:Tr = k x V/Atk = 0.049V= 492, 480 ft3At =16, 088 ft2Tr = 0.049 x 492,480/16,088Tr = 1.5 s

For 125 HZ:Tr = k x V/Atk = 0.049V= 492, 480 ft3At =9,593 ft2Tr = 0.049 x 492,480/9,593Tr = 2.52 s

Computing ratio deficiency:= 2.52/1.5= 1.68 Ratio should be between 1.6 and 1.85 to offset hearing deficiency.

III. Acoustic Construction

a.) Wall

The auditorium features both sound absorption and diffusion which can be achieved by using a Tunde Absorber/Diffusion panels mounted on walls.

Composition 6-7 PCF density fiberglass core Chemically hardened edges Perforated laminate face with randomized pattern of 1/2 inch diameter holes Fabric faced with factory in-stock fabric by Guilford of Maine, or factory-approved customer-selected material

1/3 Octave Center, Freq (Hz)1-1/8" Thick with 5/8" Holes; Absorption Coefficient per ASTM C423

1000.01

1250.1

1600.18

2000.25

2500.37

3150.61

4000.79

5000.93

b.) Floor Soundproofing, Sound control and Noise Absorption Carpet SoundproofingFloor soundproofing the act of reducing the disruptive impact noise carried through the floor and walls is one of the main features of carpet.Do you throw regular parties at your house or apartment? Your neighbors will thank you if the living space is carpeted. Since carpet is an exceptional sound absorber, carpet can reduce the sound of walking by 25 to 34 decibels whereas laminate flooring reduces surface sounds by only 1 to 6 decibels. Consider it a gift to your neighbors.At the same time, carpet reduces noise in the living space itself, as well as noise from neighbors. The reverberation time (reflection time for sound waves) in a carpeted room is halved compared to a space with hard flooring, creating a soft atmosphere where people talk more quietly. In addition, carpet also substantially reduces noise nuisance from road traffic and construction work.Compared to hard flooring, the generated sounds in a carpeted room are lower. In addition, the duration of the reflected sounds is shorter, so theres no irritating distortion. This enables people to talk more softly.

Sound ControlSound Control Floor Underlay Specifications

MaterialRecycled rubber

PatternFlat sanded face, performance engineered, diagonal grooves

FeaturesGrooved underside minimizes underlay contact between finished materials and sub-floor. Reduces ceramic tile breakage caused by cracking and fissuring of concrete slabs. Excellent floor to floor soundproofing.

ApplicationsFor use as a subfloor in new and renovation construction projects. Reduces impact noise and vibrations while reducing airborne sound transmission. Great under hardwood, ceramic or carpet. Can be used as finished floor.

Thickness1/2

SizesNominal 46

Weight65 lb.

ColorBlack

Thermal Resistance65 lb.

When soundproofing floors that are to be carpeted, first install furring strips around the rooms perimeter, then lay acoustic mats and underlayment between, and butting up against, the furring strips. Attach tackless stripping to the furring strips and lay the carpet.

Diagram Key

13/4 Wood Flooring

2Floor Furring Strip 5/83-1/2 every 10

3Quiet Floor NP 1/2 Sanded Top

4Light Concrete Floor Slab 1-1/2

5Insulation Board

63/4 or 5/8 Plywood

7Joist or Beam

8Acoustic Wool 6

9Flexible Bar

102 Layers Gypsum Board

Noise AbsorptionAcoustical Performance

IICSTC

Diagram 16370

Impact Insulation Class (IIC)Single-number rating that indicates the amount of impact noise isolation provided by a floor/ceiling assembly. The higher the number, the quieter the floor/ceiling assembly.Sound Transmission Class (STC)The Sound Transmission Class is a single number rating of the effectiveness of a material or construction assembly to retard the transmission of airborne sound. The sound transmission loss between the source and receiving rooms are plotted on a graph by frequency and sound level in decibels. The STC curve is a sliding contour that is fitted to the performance data plotted in a manner that will allow no more than 32 deficiencies below the appropriate contour. The maximum deficiency at any given frequency shall not exceed 8 decibels.Once the appropriate contour has been selected the STC is determined by the decibel value of the vertical scale at 500 Hz. The STC is expressed as a single STC number (Example STC 32)Note that the STC contour is similar to the inverse of the equal loudness contour, insofar as it discounts the lower frequency sounds to reflect how our ears perceive the lower frequency sounds.c.) CeilingThis design uses acoustical reflector panels for its ceiling for better sound reflection.Reflectors are used to optimize the strength and timing of reflected sound to all audience locations. World famous pavilions achieve this with complex shaping of walls and ceilings. Properly located, designers can use acoustical reflectors to achieve similar results at much lower costs.

Specifications: 1/2" plywood core with standard (stock) gel coat colors or optional custom colors Specify glossy (standard) or matte (optional) finish. Also available with optional laminate facing or hardwood veneer on a 3/4" core board Painted steel reinforcing angles Standard sizes up to 20' in length with width varying between 9'-4" to 10' depending on desired finish. Maximum with: Laminate or Veneeer: 10' Glossy Gel Coat: 9'-10" Matte Gel Coat: 9'-4" Approximate weight varies based on panel size and type. Minimum 2-1/2 psf

Acoustical PerformanceFrequency, Hz125250500100020004000NRC

Mounting0.1500.030.040.050.140.05

The Noise Reduction Coefficient (commonly abbreviated NRC) is a scalar representation of the amount of sound energy absorbed upon striking a particular surface. An NRC of 0 indicates perfect reflection; an NRC of 1 indicates perfect absorption.

IV. Sound Systema.) Speaker Placement

For sound system, it doesnt need a lot of loudspeakers, it actually depends on the architectural properties of the auditorium. Shown below are the proposed speaker placement for the auditorium.

Speaker System

Stage Monitor Speaker

Panaray 310M

Frequency Range: 55Hz-19kHz

Nominal Dispersion: 60 H x 120 V

Maximum SPL @ 1m: 111 dB SPL

Hanging Concert Speakers

RoomMatch RM286005 and RM602805

Frequency Range: 55Hz-16kHz

Nominal Dispersion: 28+45 x 20

Sensitivity (SPL / 1 W @ 1 m):

LF No EQ:94 dB

LF With EQ:93 dB

HF No EQ:109 dB

HF With EQ:104 dB

Stage Front Speakers

Panaray 802 Series III

Frequency Range: 50Hz-16kHz

Nominal Dispersion: 120 H x 100 V

Maximum SPL @ 1m: 116 dB SPL

Small format under-balcony speaker

RoomMatch Utility RMU108

Frequency Range: 80Hz-16kHz

Nominal Dispersion: 90 x 60

Calculated Maximum SPL @ 1 m: 114 dB

Bill of MaterialsItem #QTYUnitDescriptionPriceAmount

1200pcsInsignia - Power Cable NS-PW06501447.7589,550.00

2100pcsAudioQuest - 10' NRG-X3 Power Cable5,915.73591,573.00

32pcsBose RoomMatch Utility RMU108 Speaker29,714.8059,429.60

42pcsBose Panaray 310M Monitor Speaker19,943.1239,886.24

54pcsBose RoomMatch RM286005 and RM602805 Speaker40,155.14160,620.56

62pcsBose Panaray 802 Series III34,732.4069,464.80

730reelHellermann Tyton Power Cable83,908.002,517,240.00

815pcsSHURE SM574,356.0065,340.00

92pcsTechno Tamashi TH-1049599.001,198.00

101pcsALTO Equalizer 31 band mono4,500.004,500.00

111pcsMICKLE MT7-USB Mixing Console4,999.004,999.00

121pcsAmplivox Freestanding Podium with 50 Watt37,647.9337,647.93

131pcsAirman Welder 350 amp 9.9 Generator250,000.00250,000.00

141pcsHP Envy Recline 27xt53,679.0053,679.00

151pcsAxel Oxygen 5 Broadcast Mising Console254,952.14254,952.14

161pcsEpson PowerLite Pro Cinema LS10000358,511.18358,511.18

1710setWeiDaMark RGB LED Stage Light Par 6424,650.72246,507.20

1850setWeiDaMark LED Dome Lights16,628.03831,401.50

TOTAL AMOUNT 5,636,500.15

Audtorium Construction2,500,000.002,500,000.00

Interior Construction and Sound Proofing1,500,000.001,500,000.00

Labor Cost845,475.02

TOTAL INVESTMENT 10,481,975.17