Measurement Report Malmö
5-‐9-‐2012
1. -‐ Introduction and objective
In-‐situ acoustic-‐vibratory measurements were performed at a lightweight 5 storey-‐building in Västra Hamnen (Malmö). Three apartments were at our disposal
to carry out the measurements. Both of them were placed on top of each other (3rd
and 4th floor of the building), allowing measurements between adjacent spaces. By
these measurements, it is planned to acquire an insight of the building in terms of sound insulation, impact sound insulation, as well as different aspects regarding its vibratory performance.
1.1.-‐ Inconveniences found
The measurements were carried out at several occasions. As the Japanese ball was only available at one of these occasions only the surface vibrations could be measured using both the taping machine and the Japanese ball. Furthermore, the instrumented hammer available did not work properly with the rest of the measurement equipment. Due to this, the mobility measurements were not carried out.
2. -‐ The construction
The building is comprised of a nine-‐storey concrete structure and adjacent wooden frame five-‐storey structures. The ceiling height is 2.40 m and the flooring is parquet throughout the studied apartments with the exception of the bathroom. In figure 1 the exterior of the building is shown.
The studied apartments are located in the lower, right hand part of the structure. A detail of the floor construction and apartment separating walls can be seen in figure 2.
Figure 2 Detail of the construction.
2.1.-‐ Rooms used for the measurements
Due to the limited amount of time available just a total number of 4 rooms (two rooms in each apartment) were measured, which can be described as follows:
-‐ Apartment 4th floor (ap401):
-‐Living room; here after denoted LivRoom401:
Volume: 101 m3
-‐ Apartment 3th floor (ap301 right below ap401):
-‐Living room; here after denoted LivRoom301 –below LivRoom401-‐:
Volume: 101 m3
-‐ Apartment 3th floor (ap302 next to ap301):
-‐Living room; hereafter denoted LivRoom302 –next to LivRoom301-‐:
Figure 3 Sketch of the apartments studied.
In figure 3 an outline of the apartments is shown. The red lines indicate approximately where the measurements along or on the walls have been made. The blue dot in the Living Room indicates the position of the measurement of the springiness. The spot was selected, as it is the weakest point on the floor.
Figure 4 shows the placement of the floor elements. The figure shows apartments with the alternate placing of the balcony, therefore the indicated measured walls (red) does not correspond to the placement of the walls in the measured apartments where the balcony is not placed by the measured outer wall.
Figure 4 Placement of the floor elements.
3. -‐ Equipment
The equipment used for the measurements is described below:
• MEMS accelerometers (Analog Devices):
ADXL 203
ADXL 202E
• 32-‐channel synchronous data acquisition system
Acquisition software Spectrum SBench 6.1
• ISO B&K tapping machine • B&K Loudspeaker
• B&K instrumented hammer • Standardised Japanese Ball • B&K Amplifiers
• Sound Level Meter B&K 2270
4. -‐ Measurements
The measurements performed (both room acoustics and vibration measurements) are hereafter presented.
4.1. -‐ Airborne sound insulation
The objective of the following is to measure the airborne sound insulation following the current standards (ISO 140-‐4 och ISO 717-‐1 and SS 25267), within the frequency range going from 50 Hz to 5000 Hz. Thus, the parameters to be extracted are R’ in third octave bands (50-‐5000 Hz), R’w and C50-‐3150.
Two loudspeaker positions (at different heights) were considered in the sending room and for each position two different measurement points were chosen both in the sending and receiving room, making a total number of 8 measurements.
First of all, the reverberation time of LivRoom401 was calculated. It will allow us
to calculate the effective absorption area, A[m2], of the receiving room according to
(V[m3] volume of the room):
𝑅𝑇 = 0.16 𝑉
𝐴
The equivalent sound pressure levels in the other rooms of interest (LivRoom401 and LivRoom301) were measured
Thus, R’ [dB] is calculated as:
𝑅! 𝑑𝐵 = 𝐿
!"#$%#&− 𝐿!"#"$%$&'+ 10log 𝑆 𝐴
Where Lsending and Lreceiving are the sound pressure level in the sending and
receiving room respectively (in decibels), A[m2] the effective absorption area and
S[m2] the surface of the partition to be studied.
The summary of the measurements done is:
Sending Room Receiving Room R'
w C50-‐3150 R'w+C50-‐3150 Soundclass Apt. Floor Room Apt. Floor Room
401 4 LivRoom401 301 3 LivRoom301 58 -‐4 54 C
301 3 LivRoom301 302 3 LivRoom302 58 -‐3 55 C
Plots with the results are presented next:
4.1.1.-‐ Sound insulation between LivRoom401 and LivRoom301
The results obtained for the floor partition between LivRoom401 and LivRoom301:
NOTE: VolReceiving Room= 101 m3 Apartition=39 m2 Results R’w=58 dB C50-‐5000=-‐3dB C50-‐3150=-‐4 dB
4.1.1.-‐ Sound insulation between LivRoom301 and LivRoom302
The results obtained for the wall partition between LivRoom301 and LivRoom302:
NOTE: VolReceiving Room= 101 m3
Apartition=15 m2 Results R’w=58 dB C50-‐5000=-‐2 dB C50-‐3150=-‐3 dB
4.2. -‐ Impact sound insulation
The objective is to measure the structure-‐borne sound insulation following the current standards (ISO 140-‐7, ISO 717-‐2 and SS 25267) within the frequency range 50 Hz -‐ 5000 Hz. In order to calculate the impact sound insulation index the tapping machine was placed at the middle of the floor in LivRoom401 and
LivRoom301 recordings with the sound level meter in third octave bands were
performed in LivRoom301 and LivRoom302 respectively. Three tapping machine positions were considered, and for each position two measurements for each room -‐receiving and sending-‐ with moving microphone were performed. As a result of this analysis, L’i in third octave bands (50-‐5000 Hz), L’nw, and Cl,50-‐2500 should be obtained.
Then, L’n [dB] is calculated as follows: 𝐿!! 𝑑𝐵 = 𝐿 ! + 10log 𝐴 10
being Li the sound pressure level in the receiving room (in decibels) and A[m2] the
equivalent absorption area, calculated from the reverberation time. The 31 m3
volume limitation has been set in the previous formula.
The summary of the measurements done is:
Sending Room Receiving Room L'
n,w Cl,50-‐2500 L'n,w+ Cl,50-‐2500 Soundclass Apt. Floor Room Apt. Floor Room
401 4 LivRoom401 301 3 LivRoom301 47 0 47 A
301 3 LivRoom301 302 3 LivRoom302 34 1 34 A
Plots with the results are presented next:
4.2.1.-‐ Impact sound insulation between LivRoom401 and LivRoom301
The results obtained for the floor partition between LivRoom401 and LivRoom301 regarding impact sound insulation are:
NOTE: VolReceiving Room= 31 (101) m3 Results L’nw=47 dB Cl,50-‐2500=0 dB
The results obtained for the wall partition between LivRoom301 and LivRoom302 regarding impact sound insulation are:
NOTE: VolReceiving Room= 31 (101) m3
Results L’nw=34 dB Cl,50-‐2500=1 dB
4.3.-‐ Sound from the Japanese ball
The sound produced and transmitted when dropping the Japanese ball from 1 meter height on the middle of the floor of LivRoom401 (sending room) was measured in all receiving rooms (LivRoom301 and LivRoom302) in the frequency range 20 Hz-‐500 Hz (time constant: fast 125 ms). In the following tables, the values of the maximum sound pressure levels are presented in third octave bands for the sending room (LivRoom401) and the receiving rooms (all other rooms) as well as the equivalent maximum A-‐weighted sound pressure level.
Floors Room Lmax (centre) [dB] Lmax (centre) [dBA] Lmax (corner) [dB] Lmax (corner) [dBA]
4 LivRoom401 101,1 62,2 101,8 63,1
3 LivRoom301 89,8 50,4 91,4 51,2
3 LivRoom302 75,1 35,1 79,9 41,1
Sound pressure [dB] produced by the Japanese Ball in LivRoom401 (sending room)
4.4.-‐ Vibrations from the Japanese ball (LivRoom401)
The vibrations produced by the Japanese ball in the frequency range from 1 Hz to 500 Hz are to be measured. It was dropped from 1 meter. Meanwhile, the response of the floor was measured as shown in figure 5. The parameters of interest are the maximum acceleration (amax) and also the lowest eigenfrequency as well as plot “acceleration versus time”. The resulting accelerations Amax and in third octave bands can be seen in tables 1 and 2.
Figure 5 Excitation point and Accelerometer placing in LivRoom401
Table 1 Maximal acceleration for surface vibrations from Japanese ball excitation
Room Amax acc5 m/s2 rms Amax acc6 m/s2 rms
LivRoom 401 1,93 1,81 0.5m Acc6 Acc5 Excitation Response 0.5m
Table 2 Acceleration in third octave bands for surface vibrations excited from Japanese ball (m/s2 rms) f(Hz) 10 16 20 25 31,5 40 50 63 80 Acc 5 0,100 0,083 0,244 0,120 0,155 0,201 0,151 0,134 0,094 Acc 6 0,213 0,073 0,212 0,290 0,080 0,194 0,097 0,046 0,064 f(Hz) 100 125 160 200 250 315 400 500 Acc 5 0,207 0,240 0,227 0,231 0,100 0,043 0,044 0,039 Acc 6 0,123 0,034 0,044 0,028 0,064 0,121 0,103 0,062
In Figure 6, one can see the response recorded by the two accelerometers attached to the floor, whilst in Figure 7 a detail of two bounces of the ball is presented.
Figure 6 Response recorded by the two accelerometers attached to the floor
Figure 7 response recorded by the two accelerometers in frequency domain
4.5.-‐ Flanking transmission (between LivRoom401 and LivRoom301)
The objective is to measure how the vibrations travel through a junction in the frequency range and 10-‐3150 Hz (when having the tapping machine as excitation source)
The vibrations induced by the tapping machine are measured with the accelerometer setup shown in figures 8-‐9. Note that the accelerometers placed on the walls (acc10-‐-‐-‐ 14 and acc25-‐-‐-‐29)
are in a vertical line and not in the horizontal.
Figure 8 Layout proposed for excitation source and accelerometers
Figure 9 Accelerometer distribution
The same measurement was performed three times in order to have a good repeatability. In figures 10-‐13 the vibrations over a flank is shown both in narrowband (figures 10-‐11) and in third octave band (figures 12-‐13). In Tables 3 and 4 the mean of the acceleration and the maximal accelerations is shown. The value for the acceleration on “Wall Below” at 40 Hz had an anomaly resulting in a value for the acceleration 10 times higher that expected. This anomaly was due to a single erroneous measurement value and has been corrected in the table.
Figure 10 Mean of vibrations over flank using tapping machine (measured along an internal wall) in narowband Acc1 Acc14 Acc13 Acc12 Acc11 Acc10 Acc9 Acc8 Acc7 Acc6
Acc5 Acc4 Acc3 Acc2
FLOOR
Acc21 Acc20
Acc19 Acc18 Acc17 Acc16 Acc15
Acc25 Acc23 Acc24 Acc26 Acc27 Acc29 Acc28 CEILING WALL WALL Acc1 Acc11 Acc10 Acc9 Acc8 Acc7 Acc6
Acc5 Acc4 Acc3 Acc2
FLOOR
Acc21 Acc20
Acc19 Acc18 Acc17 Acc16 Acc15
Acc25 Acc23 Acc24 Acc26 Acc27 Acc29 Acc28 CEILING WALL WALL
Figure 11 Mean of vibrations over flank using tapping machine (measured along an outer -‐facade-‐ wall) in narrowband
Figure 12 Mean of vibrations over flank using tapping machine (measured along an internal wall) in one third octave band
Figure 13 Mean of vibrations over flank using tapping machine (measured along an outer -‐facade-‐ wall) in one third octave band
Table 3 Accelerations over flank in third octave bands Frequency (Hz) (mm/sWall Up 2) Floor Inner (mm/s2) Floor Outer (mm/s2) Wall Down (mm/s2) Ceiling Inner (mm/s2) Ceiling Outer (mm/s2) 10 2,00 5,81 3,19 1,83 4,67 2,27 16 1,96 14,57 3,43 1,35 4,55 2,42 20 2,08 10,57 5,52 2,24 3,33 3,34 25 2,97 18,43 7,65 4,73 4,77 6,48 32 2,99 21,15 5,25 1,82 6,55 3,46 40 2,64 20,68 13,06 3,06 9,69 7,30 50 3,16 22,31 7,77 2,44 13,29 11,50 63 3,03 18,66 8,46 2,94 14,91 6,19 80 3,16 28,92 13,84 2,84 22,91 10,05 100 5,01 24,93 18,66 2,20 17,24 12,41 125 4,39 27,10 24,48 2,10 14,93 14,59 160 3,44 25,30 21,61 1,83 16,09 12,76 200 5,37 23,97 19,85 2,39 16,47 12,91 250 10,24 23,62 21,68 3,18 14,24 13,93 315 15,08 31,28 23,10 1,77 7,05 5,09 400 16,86 45,12 17,39 1,52 4,81 3,55 500 9,94 27,02 12,69 1,39 2,61 2,17 630 10,93 38,84 13,71 1,31 2,86 2,23 800 8,28 45,49 12,55 1,28 2,44 2,06 1000 7,05 39,83 13,62 1,27 1,81 1,71 1250 7,70 49,96 17,88 1,11 1,61 1,51 1600 9,92 76,92 23,97 1,02 1,52 1,45 2000 8,00 60,17 26,22 0,95 1,35 1,32 2500 4,83 35,54 22,84 0,84 1,19 1,20 3150 2,51 26,83 16,60 0,76 1,12 1,08
Table 4 Maximal acceleration over flank
Wall Up (m/s2) Floor Inner (m/s2) Floor Outer (m/s2) Wall Below (m/s2) Ceiling Inner (m/s2) Ceiling Outer (m/s2) 0,46 3,05 1,25 0,10 0,31 0,25
4.6.-‐ Surface Vibration of the Floor (LivRoom401)
The objective is to measure and analyse how the vibrations travel through the floor and how they are dampened from the source. The frequency ranges of interest are 1-‐500 Hz when exciting with the Japanese ball and 20-‐3150 Hz when exciting with the hammer machine.
The excitation was at the middle of LivRoom401 when dropping the Japanese ball from 1 m height and the tapping machine. The accelerometers’ setup is shown in Figure 14.
Figure 14 Measurement layout. Acc 1-‐5 in along direction. Acc 6-‐10 in across direction
Figure 15 Floor vibrations from tapping machine in narrow band. Along direction.
Figure 16 Floor vibrations from tapping machine in narrowband. Across direction 0.5m Acc6 Acc5 Excitation Response Acc1 Acc3 Acc4 Acc2 0.32m 0.5m 0.5m 0.375m 0.5m Acc7 Acc8 Acc9 Acc10
Figure 17 Floor vibrations from tapping machine in one third octave band. Along direction
Figure 18 Floor vibrations from tapping machine in one third octave band. Across direction
Figure 20 Floor vibrations from Japanese ball in narrowband. Across direction
Figure 21 Floor vibrations from Japanese ball in third octave band. Along direction
Table 5 Accelerations from Japanese ball Amax (mm/s^2 rms) positions as in figure 13.
f(Hz) acc1 acc2 acc3 acc4 acc5 acc6 acc7 acc8 acc9 acc10 10 26,76 53,21 78,11 79,96 99,72 213,38 209,12 204,63 144,00 82,89 16 20,50 57,20 92,47 122,71 83,18 73,44 152,04 218,36 189,27 123,58 20 94,32 196,00 273,33 301,16 244,37 211,59 57,43 168,48 231,19 180,47 25 83,99 141,33 183,54 184,03 119,65 290,22 211,18 119,62 277,73 246,88 32 159,08 234,90 274,21 293,79 154,51 80,12 135,39 121,18 177,97 160,86 40 121,66 197,07 229,22 251,32 200,75 194,29 63,12 211,71 115,14 113,21 50 174,86 205,07 207,31 245,86 151,32 97,18 122,13 142,55 46,04 47,39 63 234,35 204,79 164,59 214,05 134,45 45,60 62,35 67,93 26,52 82,09 80 193,54 169,25 110,36 141,46 93,68 64,21 124,30 65,27 27,66 63,08 100 78,18 65,49 78,06 173,72 206,86 123,46 136,25 64,56 21,96 40,92 125 28,97 17,27 97,30 49,57 240,48 34,36 39,47 16,09 9,72 16,55 160 30,67 40,28 134,61 75,41 226,64 44,16 16,32 15,59 5,62 9,70 200 18,92 45,67 30,33 64,74 230,71 28,29 15,09 21,65 9,56 7,03 250 25,19 33,50 63,53 118,78 99,60 63,74 11,75 15,14 10,02 7,40 315 23,45 26,31 23,28 76,17 42,91 120,83 39,99 22,46 19,36 10,32 400 22,73 19,71 25,90 33,49 44,09 103,21 90,30 43,22 30,85 24,12 500 16,40 14,19 18,58 19,16 38,79 61,82 55,44 62,23 31,58 17,64 630 16,88 8,84 9,24 23,07 32,79 71,61 75,80 46,91 42,82 22,49 800 10,03 5,14 8,45 16,72 67,11 111,03 77,41 60,71 38,96 31,13 1000 7,96 7,36 13,54 28,25 59,86 84,71 49,47 36,25 32,91 23,68 1250 8,24 8,66 15,28 34,32 50,34 39,96 33,91 30,05 24,54 15,81 1600 9,82 10,56 18,34 25,50 37,96 31,38 50,11 53,17 48,18 35,20 2000 7,81 9,99 24,97 36,97 30,12 34,49 43,23 37,77 40,20 22,99 2500 4,96 7,71 11,75 22,85 17,66 20,22 20,48 12,69 17,46 6,00 3150 3,10 5,43 7,07 15,79 17,01 22,75 18,24 11,21 9,39 8,10
Table 6 Maximal acceleration from Japanese ball on floor. Positions as in figure 13
Point Amax (m/s2) Point Amax (m/s2)
acc1 0,71 acc6 1,81 acc2 0,84 acc7 1,58 acc3 1,11 acc8 1,32 acc4 1,53 acc9 1,15 acc5 1,93 acc10 0,84 4.7.-‐ Wall Response
The objective was to calculate the lowest eigenfrequency of the structure when hitting the wall with an instrumented hammer with a rubber tip.
Figure 23 Measurement disposition on the walls. X and Y signifies distances as shown in table 7
Table 7 positions for excitation point and measurement point as indicated in figure 22
x y Inner Wall 0,86m 1,75m Apartment separating wall 0,86m 1,0m
Note: the force transducer of the instrumented hammer available didn’t work and therefore no correlation with the impact force can be made.
Figure 24 Vibrations on inner -‐apartment separating-‐ wall in narrow band
y Acc14 Excitation Response x y x Hammer
Figure 25 Vibrations on inner -‐apartment separating-‐ wall in third octave bands
Figure 27 Vibrations on inner wall in third octave bands
4.8.-‐ Springiness
The springiness was measured to be 0,3mm using the equipment shown in figure 28.
Figure 28 Setup to measure springiness 4.9.-‐ Mobility
