\\SAXDESKTOPNEW\Job Folders\200204 570 Crespi Drive IS\Word\570 Crespi Drive Construction Noise Memo 1‐11‐22.docx See Appendix B for interior noise calculations.
I hope this information is helpful, please call or email me if you have any questions.
Sincerely,
Saxelby Acoustics LLC
Luke Saxelby, INCE Bd. Cert.
Principal Consultant
Board Certified, Institute of Noise Control Engineering
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Packet Pg. 861 Attachment: Attachment J - Construction Noise Memorandum (4911 : 570 Crespi Mixed-use Project) Appendix A: Acoustical Terminology
Acoustics The science of sound.
Ambient Noise The distinctive acoustical characteristics of a given space consisting of all noise sources audible at that location. In many cases, the term ambient is used to describe an existing or pre‐project condition such as the setting in an environmental noise study.
ASTC Apparent Sound Transmission Class. Similar to STC but includes sound from flanking paths and correct for room reverberation. A larger number means more attenuation. The scale, like the decibel scale for sound, is logarithmic.
Attenuation The reduction of an acoustic signal.
A‐Weighting A frequency‐response adjustment of a sound level meter that conditions the output signal to approximate human response.
Decibel or dB Fundamental unit of sound, A Bell is defined as the logarithm of the ratio of the sound pressure squared over the reference pressure squared. A Decibel is one‐tenth of a Bell.
CNEL Community Noise Equivalent Level. Defined as the 24‐hour average noise level with noise occurring during evening hours (7 ‐ 10 p.m.) weighted by +5 dBA and nighttime hours weighted by +10 dBA.
DNL See definition of Ldn.
IIC Impact Insulation Class. An integer‐number rating of how well a building floor attenuates impact sounds, such as footsteps. A larger number means more attenuation. The scale, like the decibel scale for sound, is logarithmic.
Frequency The measure of the rapidity of alterations of a periodic signal, expressed in cycles per second or hertz (Hz).
Ldn Day/Night Average Sound Level. Similar to CNEL but with no evening weighting.
Leq Equivalent or energy‐averaged sound level.
Lmax The highest root‐mean‐square (RMS) sound level measured over a given period of time.
L(n) The sound level exceeded a described percentile over a measurement period. For instance, an hourly L50 is the sound level exceeded 50% of the time during the one‐hour period.
Loudness A subjective term for the sensation of the magnitude of sound.
NIC Noise Isolation Class. A rating of the noise reduction between two spaces. Similar to STC but includes sound from flanking paths and no correction for room reverberation.
NNIC Normalized Noise Isolation Class. Similar to NIC but includes a correction for room reverberation.
Noise Unwanted sound.
NRC Noise Reduction Coefficient. NRC is a single‐number rating of the sound‐absorption of a material equal to the arithmetic mean of the sound‐absorption coefficients in the 250, 500, 1000, and 2,000 Hz octave frequency bands rounded to the nearest multiple of 0.05. It is a 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.
RT60 The time it takes reverberant sound to decay by 60 dB once the source has been removed.
Sabin The unit of sound absorption. One square foot of material absorbing 100% of incident sound has an absorption of 1 Sabin.
SEL Sound Exposure Level. SEL is a rating, in decibels, of a discrete event, such as an aircraft flyover or train pass by, that compresses the total sound energy into a one‐second event.
SPC Speech Privacy Class. SPC is a method of rating speech privacy in buildings. It is designed to measure the degree of speech privacy provided by a closed room, indicating the degree to which conversations occurring within are kept private from listeners outside the room.
STC Sound Transmission Class. STC is an integer rating of how well a building partition attenuates airborne sound. It is widely used to rate interior partitions, ceilings/floors, doors, windows and exterior wall configurations. The STC rating is typically used to rate the sound transmission of a specific building element when tested in laboratory conditions where flanking paths around the assembly don’t exist. A larger number means more attenuation. The scale, like the decibel scale for sound, is logarithmic.
Threshold The lowest sound that can be perceived by the human auditory system, generally considered of Hearing to be 0 dB for persons with perfect hearing.
Threshold Approximately 120 dB above the threshold of hearing. of Pain
Impulsive Sound of short duration, usually less than one second, with an abrupt onset and rapid decay.
Simple Tone Any sound which can be judged as audible as a single pitch or set of single pitches.
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Packet Pg. 862 Attachment: Attachment J - Construction Noise Memorandum (4911 : 570 Crespi Mixed-use Project) Interior Noise Calculation Sheet
Project:
Room Description:
Parallel Exterior level, dBA: 79 Leq
Correction Factor, dBA: 5
Noise Source:
Room Length, ft: 10
Room Width, ft: 15
Room Height, ft: 9
Transmitting Panel Length, ft: 10
Transmitting Panel Height, ft: 10
Ceiling Finish:
Ceiling, sf: 150
Wall Finish 1:
Wall Finish 1, sf: 437.5
Wall Finish 2:
Wall Finish 2, sf: 12.5
Floor:
Floor, sf: 150
Misc. Finish:
Misc. Finish, sf:
Transmitting Element 1:
Element 1, sf: 100
Transmitting Element 2:
Element 2, sf:
Transmitting Element 3:
Element 3, sf:
Transmitting Element 4:
Element 4, sf:
Predicted Interior Noise Level, dBA: 52
570 Crespi Drive580 Crespi Commerical Use ‐ Regular Construction Gyp Board
Gyp Board
Diesel EngineWall ‐ Wood with Sheath
Appendix B1:
Inputs
Soft FurnishingsWoodGlass
53 53
60 60 60
66 66 66
74 74 74 75 75 75
72 72
41 41 42 40
37 45
39 37
43 41
38 37 36 37
33 30
‐10
0 1020304050607080
125 160 200 250 315 400 500 630 800 1K 1.25K 1.6K 2K 2.5K 3.15K 4K dBA
1/3 Octave Band Center Frequency
Exterior Noise Level Predicted Interior Noise Level
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Packet Pg. 863
Attachment: Attachment J - Construction Noise Memorandum (4911 : 570 Crespi Mixed-use Project) Interior Noise Calculation Sheet
Project:
Room Description:
Parallel Exterior level, dBA: 67 Leq
Correction Factor, dBA: 5
Noise Source:
Room Length, ft: 10
Room Width, ft: 15
Room Height, ft: 9
Transmitting Panel Length, ft: 10
Transmitting Panel Height, ft: 10
Ceiling Finish:
Ceiling, sf: 150
Wall Finish 1:
Wall Finish 1, sf: 437.5
Wall Finish 2:
Wall Finish 2, sf: 12.5
Floor:
Floor, sf: 150
Misc. Finish:
Misc. Finish, sf:
Transmitting Element 1:
Element 1, sf: 100
Transmitting Element 2:
Element 2, sf:
Transmitting Element 3:
Element 3, sf:
Transmitting Element 4:
Element 4, sf:
Predicted Interior Noise Level, dBA: 39
570 Crespi Drive580 Crespi Commerical Use ‐ Regular Construction ‐ 10' Wall Gyp BoardGlassWoodSoft FurnishingsWall ‐ Wood with Sheath Appendix B2:
Inputs
Diesel EngineGyp Board
41 41
48 48 48
54 54 54
62 62 62 63 63 63
60 60
29 29 30 28
25 32
26 24
30 28
25 25 24 25
21 18
‐10
0 10203040506070
125 160 200 250 315 400 500 630 800 1K 1.25K 1.6K 2K 2.5K 3.15K 4K dBA
1/3 Octave Band Center Frequency
Exterior Noise Level Predicted Interior Noise Level
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Packet Pg. 864
Attachment: Attachment J - Construction Noise Memorandum (4911 : 570 Crespi Mixed-use Project)