PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Survey method for rubber ball impact soundJeong-Ho Jeong11Fire Insurers Laboratories of Korea, Republic of Korea

ABSTRACT
Rubber ball impact sound was standardized in ISO standard as for precision and engineering method in ISO 10140 series
and ISO 16283-2. Also, a single number quantities for rubber ball impact sound is standardizing. In order to improve lowfrequency impact sound isolation performance, quality control in a construction site is one of a necessary point to get reliable
isolation performance. A survey method for airborne and light-weight impact sound was regulated in ISO 10052. However,a survey method for rubber ball impact needs to be proposed. To proposed survey method for rubber ball impact sound, theproposed method should be correlated well with measurement results which were measured with precision or engineering
method. In this study, field measurements were conducted using KS F 2810-2 with five impact positions and five receiving
points in Korean apartment buildings and the results were compared with survey method results which are extracted fromthe field measurement results.

Keywords: Rubber ball, Floor impact sound, Survey method, Quality Control

1. INTRODUCTION
Rubber ball impact sound isolation performance can be measured in laboratory and field conditions
according to ISO 10140-3 or KS F 2810-2, ISO 16283-2 respectively. In order to measure the rubber
impact sound isolation performance the centre point and 3 ~ 4 boundary points of the upper unit areused for impact points. Also spatially averaged from measurement results at centre points and 3 ~ 4receiving points of the lower unit of apartment buildings. In Korea, the height of the receiving point
is from 1.2 m to 1.5 m from the floor (see Figure 1. (a)). Floor impact sound isolation performancemeasurement method for the floor system of the apartment buildings or resilient material using rubberball is a method for precision or engineering methods and requires a lot of time and high -quality
measurement equipment. A study (Ming Li, 2014) was carried out to simplify the measurement methodwith time and equipment in case of light-weight impact sound.
In general, noise or sound measurement methods are classified into Accuracy Grade 1, 2, and 3
according to the level of accuracy. Survey measurement methods are based on precision or engineering
measurement methods and are defined as methods to be used for product screening and quality control
by deriving simple measurement methods. Many studies have been carried out to improve the floor
impact sound isolation performance and various floor impact sound isolation system have beendeveloped, however, it has been reported that there is a large variation in performance between eachapartment unit and quality control of construction stage and after the installation of finishing materials.
In recent years, there has been an increasing interest in the quality control of floor impact soundisolation system to minimize such construction variations.
The survey method of light impact sound using a tapping machine was standardized in ISO 10052.
Survey method of light-weight impact sound standardized to generate a light-weight impact sound at
two or three points and a sound level meter in a lower receiving room to hold a space average of thearm length for about 30 s. Test results by ISO 10052 are reported to be similar to those measured byengineering measures (ISO 140-7) (Chiara M. Pontarollo, Antonino Di Bella, 2013). However, there
is no study on the survey method of the rubber ball impact sound.
In this study, the results from survey methods that can be used for the quality control of floor
impact sound isolation system in the field condition were compared with the results measured
according to KS F 2810-2.͑As a simple measurement method for the quality control of the rubber ball
impact sound, the measurement was made at the center of the lower receiver room, and the case of
having the center point in the upper room was compared with the case of having the center point andone boundary point.͑
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jhjeong92@gmail.com

2. SET UP FOR SURVEY METHOD OF RUBBER BALL IMPACT SOUND
In order to compare the measurement method of rubber ball
impact sound, the impact sound of the rubber ball was measured
according to KS F 2810-2 for the apartment buildings where thefinishing was completed and the floor finishing material was notapplied; where resilient material for reducing rubber ball impact
sound and mortar only. The measured buildings where were all about
270 m2 wide and from three to nine units were measured for eachfloor plans. For comparison of the survey method, the rubber ball
impact sound level was compared between the impact point and thereceiving point for the unit of the upper and lower generations (seeFigure 12). In Figure 1, I1 is the centre point, I2, I5 are the two points
located inside the apartment house, and I3 and I4 are the points
located on the window side. In the case of the receiving po int, R3 isthe centre point, R1 and R5 are the indoor sides, and R2 and R4 are
the outer window side.
As shown in Figure. 2, the difference between the averagefrequency characteristics and each impact points was small in thecase of the impact point on the window side (I4) in both cases wherefinishing materials were applied and not applied.

Figure 1 Measurement setup
for rubber ball impact soundaccording to KS F 2810-2(a) With finishing materials(b) Without finishing materials
Figure 2 Averaged rubber ball impact sound pressure level at 5 impact positions in upper units(b) With finishing materials(b) Without finishing materials
Figure 3 Averaged rubber ball impact sound pressure level at 5 receiving positions in lower units

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Previous studies on the survey method of light-weight impact sound have shown that the I2 positionis suitable for survey method. Figure 3 compares the measurement results of the receiving points withthe average spectrum, and the centre point (R1) and R4 point have the most similar characteristics.
The impact point location for the survey method of rubber ball impact sound was compared andanalyzed with the centre point (I1), I2, I4 position. In the case of receiving points, the centre point(R1), and R4 point was used. The combination of the impact point and the receiving point is composedof six cases and was shown in Figure 4(a) Centre to Centre(b) Centre to Centre+R4(c) Centre +I2 to Centre(d) Centre + I2 to Centre + R4 (e) Centre + I4 to Centre (f) Centre + I4 to Centre+R4Figure 4 Impact and receiving point setups for the comparison of the survey method of rubber ball
impact sound3.

COMPARISON BETWEEN SURVEY METHODS

The results of the precision measurement and the survey method were shown in Figures 5 ~ 6,respectively. In ISO 10052, the difference in sound pressure level between the results measured by
the survey method and those measured by the precision or engineering measurement method is shown
to be within ± 2 dB. Therefore, the limit of the difference between the proposed method and the KS F
2810-2 was set to ± 2 dB.
Figure 5 shows the analysis results for the 25 apartment units with 4 kinds of floor plan where
installation of finishing material had been completed. In the combination of the six survey methods,
it was found that there was a difference of less than 2 dB in the frequency range over 63 Hz bands. In
the case of the impact point, the difference was small when the impact points were center point (I 1),
the center point (I1) and I4 point. In addition, it was found that the difference became smaller whenboundary receiving point (R4) and center receiving point (R3) were included as receiving points.
When the centre impact point (I1) and I4 point were set up as impact points and the center point (R3)and R4 were set up as receiving points, most of the differences are distributed within 1 dB range.

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(a) Floor plan A(b) Floor plan B(c) Floor plan C(d) Floor plan D
Figure 5 Comparison of rubber ball impact sound pressure level characteristics of the apartment
units with finishing materials between the results of the engineering method (KS F 2810 -2) andproposed survey methods(a) Floor plan A(b) Floor plan B(c) Floor plan C(d) Floor plan D
Figure 6 Comparison of rubber ball impact sound pressure level characteristics of the apartment
units without finishing materials between the results of the engineering method (KS F 2810 -2) andproposed survey methods

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Figure 6 shows the results of analysis for 15 apartment unit without finishing material with 4 kindsof floor plans. In this cases of floor and wall cladding and some doors not installed, therefore thedifference between engineering method and survey method was larger than in the case of the apartment
house where the finishing materials were installed (see Figure 5). In the case of center impact point(I1) and receiving center point (R3), the differences were often larger than 2 dB. When the I2 point isadded, the difference between the frequency bands was became larger. When the I4 is added, the level
difference became smaller than that of I2. There was a tendency, as in the case of apartment unit wherefinishing materials were installed (see Figure 5), that the level differen ce in the measurement band
was reduced when the central point (R3) and R4 are calculated together.
In the case where the impact point and the receiving point are set as a centre point, the level
difference from the overall measurement result was sometimes larger than 2 dB. The point where theimpact point or the receiving point is selected most similar to the engineering measurement result iswithin 2 dB difference. In the case of two impact points including the centre point and two receiving
points including the centre point, the level difference from the engineering measurement result is lessthan 1 dB. As a survey method for measuring the rubber ball impact sound, it was consideredappropriate to impact and receive at two points including the centre point or the centre point. It isnecessary to indicate that the level difference may deviate from 2 dB in case of the centre to centrecase. It can be recommended that the method of receiving at two points including the centre point andimpact at two points including the centre point because the level difference was smaller than othersurvey method setup.

4. RRESUTLS AND DISCUSSION
According to the measurement method of KS F 2810-2, there are five impact points including thecentre point and five receiving points containing the centre point. The difference between themeasurement results obtained by KS F 2810-2; engineering method, method and the results of the six
survey methods were calculated and compared. It was found that there was a difference of less than
2dB between the centre impact point to the centre receiving point and engineering method. However,the difference between the centre impact point to the centre receiving point was larger than 2dB. In
case of adding one impact or receiving point with the most similar characteristics to the engineering
measurement results, the level difference from the engineering measurement result was less than 2 dB.
It is analyzed that the level difference was about 1 dB in the entire frequency band when calculatedwith the setup with two impact points including the centre point and two receiving points including
the centre point.
Table 1 – Single number quantity correlation coefficient and the level difference of rubber ball
impact sound pressure level between engineering method and survey methods
With finishing materials
Without finishing materials
CaseCorrelation
Average of level
Correlation
Average of level
coefficientdifference
coefficientdifference
Case 1
0.617
-0.04
0.789
-2.49
Case 20.679
0.03
0.817-1.17
Case 3
0.718
0.44
0.904
-0.69
Case 4
0.868
0.56
0.959
-0.05
Case 5
0.694
0.41
0.853
-1.04
Case 6
0.800
0.44
0.840
-0.08
Along with the characteristics of each frequency band, the important measurement result is a single
number quantities. Table 1 shows the correlation between the single number quantities calculated fromthe engineering measurement results and the single number quantities calculated by the six survey
methods. Results of correlation analysis showed that increasing the number of impac t points and thenumber of receiving points increased the correlation coefficient with the single number quantities ofthe measurement results with the engineering method.
In the case of the difference of single number quantities for the six survey methods for twoapartments buildings by the presence of the finishing materials, the correlation analysis showed thatthe case where only the centre point was impacted and received; Case 1, the average single number
quantity difference was the smallest, but the average difference was the largest in the apartment where5048

the finishing materials were not installed. The condition with the smallest average difference of thesingle number quantities by the presence or absence of finishing was Case 6, which was excluded
from the central point and one additional point. Correlation analysis for single numerical quantities,
average level difference and characteristic difference analysis by frequency band can be recommended
as a survey method for the center point and the method of impact and receiving at one additional point.

REFERENCES
1. ISO 10140-3, Acoustics -- Laboratory measurement of sound insulation of building elements -- Part 3:
Measurement of impact sound insulation; 2010.
2. KS F 2810-1, Field measurements of floor impact sound insulation of buildings ̿ Part 2: Method using
standard heavy impact sources; 2017.G
3. ISO 16283-2, Acoustics -- Field measurement of sound insulation in buildings and of building elements - Part 2: Impact sound insulation; 2018.
4. J. H. Jeong, S. C. Lee and J. Y. Hong. Survey method of light weight impact sound isolation performancefor the quality control of floor impact sound isolation system. Journal of KIAEBS; Vol.13, No,1; 2019,p.1-15.
5. Ming Li. Simplified measurement method for impact sound insulation in buildings, Doctoral dissertationof The University of Auckland; 2014.
6. ISO 10052:2004 Acoustics - Field measurements of airborne and impact sound insulation and of service
equipment sound - Survey method.
7. Chiara Martina Pontarollo, Antonino Di Bella. Comparison between field measurements methods ofacoustic performances of buildings; 2013, proceeding of AIA-DAGA 2013 Merano.

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