Sound & Acoustics In Technology Classrooms · Sound & Acoustics In Technology Classrooms ......
Transcript of Sound & Acoustics In Technology Classrooms · Sound & Acoustics In Technology Classrooms ......
David P. Stadler CTS, DMC-E, MS
Senior Manager
Media Technology Services
Carnegie Mellon University
Sound & Acoustics In Technology Classrooms
• Established 1900
• Private research university
• 1,368 Faculty
• 6,000 Undergraduates & 5,420 Graduate & Doctoral students
• Main campus: Pittsburgh, Pennsylvania
• Undergraduate branch campus: Doha, Qatar
• 13 graduate branch campuses in 11 countries
• Athletics: 17 Division III athletic teams - Tartans
Carnegie Mellon University Fast Facts
• Classroom Technologies
• Media Production
• Videoconferencing
• AV & Media Consultation
• Facility Design
Media Technology Services
David P. Stadler CTS,MS
Senior Manager
Media Technology Services
Carnegie Mellon University
Qualifications and Biases
A: 10
C: 100
B: 64
D: 18
50:50
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How many total
campuses are in the
SUNY system??
Has your college or university ever conducted an acoustical evaluation of your learning spaces?
A. Yes
B. No
What priority do you give sound in designing an integrated media learning space?
A. Sound then display
B. Display and sound equal
C. Display then sound
What was the percentage of acoustical exhibitors who were on the Infocomm 2010 show floor?
A. 2%
B. 5%
C. 20%
D. 30%
InfoComm 2010
• 925 exhibitors
• 21 acoustical exhibitors
representing 2% of exhibitors
a/V Manufacturers • Historically focused on maximizing visual
displays
Digital revolution
•Auditory content- second string
How do we see classroom sound?
How do we see classroom sound?
Learning Space Acoustical Standards
Acoustic Basics
• Sound Isolation
Sound Ratings
Signal to Noise ratio (S/N)
• Reverberation
• Reflected Sound
• Room Modes
Sound Isolation
• Keep out exterior room sound
• Preserve generated sound inside a room
• Reduce unwanted interior room sound
• Implement during construction
Architectural components – Walls, Doors Floors, Ceilings, HVAC
Sound Isolation – Rating Systems
• STC- Sound Transmission Class
Based on ASTM E413-87 (1994)
125-4000 Hz
Typically used for speech and media
• OITC-Outdoor Indoor Trans. Class
Based on ASTM E1332 (1990)
80-4000 Hz
Typically used for exterior sound
Sound Isolation
• STC for walls - higher STC values more efficient in reducing sound transmission
STCratings.com
Sound Isolation
Changes in STC rating Changes in apparent loudness
+/- 1 Almost imperceptible
+/- 3 Just perceptible
+/- 5 Clearly noticeable
+/- 10 Twice as loud
+/- 20 Four times as loud
STCratings.com
Demonstration
Learning Space Sound Isolation Recommendations
• Wall ceiling and floor if adjacent to:
STC-45: corridor, staircase, office or conference room
STC-50: core learning space, speech clinic, health care room or outdoors
STC-53: restroom
STC-60: music room, mechanical equipment room, cafeteria, gymnasium or indoor swimming pool
• Door ratings:
STC -30: classroom doors
STC-40: music room doors
STC-45-60: ancillary space separation
Acoustics.com
STC • Use as a reference for targeting new
construction and architecture
• Calculation
Best left to the professionals
• Do it yourself
Small room acoustic forum http://forum.studiotips.com/viewtopic.php?t=140
Sound Isolation
Isolation will be improved by extending walls to structural deck, not just the ceiling.
A. True
B. False
STCratings.com
Sound Isolation
Sound will travel through speaker and electrical outlet penetrations.
A. True
B. False
STCratings.com
Demonstration
Sound Isolation
Installing insulation within a wall or floor/ceiling cavity will improve the STC by 4-6 points.
A. True
B. False
STCratings.com
Sound Isolation
Changes in STC rating Changes in apparent loudness
+/- 1 Almost imperceptible
+/- 3 Just perceptible
+/- 5 Clearly noticeable
+/- 10 Twice as loud
+/- 20 Four times as loud
STCratings.com
Sound Isolation
Metal studs perform better than wood studs.
A. True
B. False
STCratings.com
Learning Space Background Noise Level
< 20,000 cubic feet < 35 dBA for spaces
> 20,000 cubic feet < 40 dBA for spaces
Need a sound-to-noise level of 15 dB.
Nelson,Soli & Seltz (2002) Acoustical Barriers to Learning- Acoustical Society of America
Reverberation
Definition:
Prolongation of the sound in a space caused by continued multiple reflections.
Acoustics.com
Reverberation
Acoustics.com
Learning Space – Reverberation Standards
Space volumes. . .
• < 10,000 cu. ft. are not relevant
• > 10,000 cu. ft. should be < 0.6 seconds
• between 10,000 and 20,000 cu. ft. should be < 0.7 seconds
• > 20,000 cu. ft. (see ANSI.ASA S12.60 guidelines )
Acoustics.com
Learning Space - Speech Intelligibility
Combination of reverberation time (RT) and signal-to-noise ratio (S/N)
• 0.5 second RT and +10 dB S/N - 90 % speech intelligibility
• 0.5 second RT and 0 S/N - 55 % speech intelligibility
• 1.5 second RT and +10 S/N – 75 % speech intelligibility
• 1.5 second RT and 0 S/N – 30 % speech intelligibility
Seep,Glosemeyer, Hulce, Linn& Aytar (2000) Classroom Acoustics- Acoustical Society of America
Reflected Sound
• Sound strikes a surface or several surfaces before reaching the receiver
• Reverberation is continuous multiple reflections
• Controlling the reverberation time in a space does not alleviate reflection problems
Acoustics.com
Reverberation & Reflected Sound Remediation
• Fiberglass/Foam non-parallel walls
• Bass Traps
• DIY
Owens Corning 703 & 705 panels 48"x 24"x__
Fabric covered
Flexible mounting
Reverberation & Reflected Sound Remediation
• Mid and high frequency traps
Reverberation & Reflected Sound Remediation
• Bass traps
4” thick 705-FRK and spaced 16 inches away from the wall can be quite effective for frequencies below 125 Hz
Room Mode
Definition
• Sound having the same pitch as a natural resonance of the room will sound louder and have a longer decay time than other notes.
Ballou, Glen, Ed., Handbook for Sound Engineers, 2nd ed, Howard Sams, Carmel, Indiana, 1991
Optimize Room Modes
• Use standard modal approach
Create as many different resonances as possible spread evenly across the frequency spectrum
• Proper space design
Create space with length, width, and height ratios that are as unrelated as possible
Ballou, Glen, Ed., Handbook for Sound Engineers, 2nd ed, Howard Sams, Carmel, Indiana, 1991
Room Mode
Optimum room dimensions
According to the modal design theory, the worst possible room shape is a cube.
Ballou, Glen, Ed., Handbook for Sound Engineers, 2nd ed, Howard Sams, Carmel, Indiana, 1991
Dimension Design #1 Design #2 Design #3
Width 1.14 x Height
1.28 x Height
1.60 x Height
Length 1.39 x Height
1.54 x Height
2.33 x Height
Realtraps.com
Realtraps.com
Room Modes - Remediation
• Bass traps can improve room modes
• Moving walls and ceilings are the only true solution
Acoustic Focus for Learning Spaces
• Background noise
All learning spaces
• Reverberation
Large learning spaces
• Reflection
All learning spaces
− Dead spots
• Room Modes
Specialized or media integrated learning spaces
How do we see classroom sound?
CMU Learning Space - Acoustic Evaluation
• Existing classrooms
Background sound level
Isolation
Reverberation
Reflection
− Dead spots
CMU Equipment Operating Noise Evaluation
• Equipment selection
• Integrated room design
High volume, low velocity
Integrated room design – component selection
2 dBA increase in baseline room noise
0 dBA
Cost Savings
Integrated room design – component selection
2 dBA increase in baseline room noise
0 dBA
Cost Premium
Crossing the Chasm Marketing and selling high-tech products to the mainstream customers
Geoffrey A. Moore
David P. Stadler CTS, DMC-E, MS
Senior Manager
Media Technology Services
Carnegie Mellon University
Sound & Acoustics In Technology Classrooms