Transparent Noise Protection
6.1 Human aspects
In the past several decades, our environment has become much louder due to mobility and industrialization. This development has become a severe problem for many people. Permanent noise represents two key dangers:. Once a person’s sense of hearing is damaged, it can start to diminish unnoticed over time, which can lead to worsening tinnitus and anblyacousia. Hearing loss may also contribute to mental illnesses that can start with insomnia, inability to concentrate (due to the tinnitus), all of which can further lead to allergies, circulation diseases, high blood pressure, even to an increased risk of heart attack.
6.2 Sound wave characteristics
|Körperschall||Sound waves as they are transmitted through a solid object|
Sound is normally transported by both through the air and through solid objects. The intensity of the variability in pressure is called sound pressure, and can be extremely variable, from the ticking of a clock to the crack of a gunshot, and is measured in decibels (dB).
|Das Lärmometer||the decibel meter|
|Wie laut – wie schädlich?||How loud – how harmful?|
|Spielzeugpistole am Ohr abgefeuert||Toy pistol fired close to ear|
|Ohrfeige aufs Ohr, Silversterböller auf der Schulter explodiert||Slap on the ear, Eve firecrackers exploded on the shoulder|
|Airbag-Entfaltung in unmittelbarer Nähe||Air bag deployment in the immediate vicinity|
|Hammerschlag in einer Schmiede aus 5 m Entfernung [Spitzenpegel].||Hammer in a forge from a height of 5 meters [peak height].|
|lautes Händeklatschen aus 1m Entfernung (Spitzenpegel)||loud hand clapping from a distance of 1m (max. distance)|
|Schmerzschwelle: Gehörschaden schon bei kurzer Einwirkung möglich||Pain threshold: possible ear damage even after short exposure|
|häufiger Schallpegel in Diskotheken, Martinshorn aus 10 m Entfernung||Frequent sound level in discotheques, Siren at distance of 10 m|
|häufiger Pegel bei Musik über Kopfhörer, Presslufthammer in 10 m Entfernung||Frequent level when listening to music through headphones, Pneumatic drill at 10 m|
|Hörschaden bei Einwirkdauer von 40 Std. pro Woche möglich||Hearing impairment possible when exposed for 40 hours per week|
|Dauerschallpegel an Hauptverkehrsstraße tagsüber||Continuous sound on the main road during the day|
|erhöhtes Risiko für Herz-Krislauf-Erkrankungen bei dauernder Einwirkung||Increased risk for cardiovascular disease if continuously exposed|
|Dauerschallpegel an Hauptverkehrsstraße nachts Kühlschrank aus 1 m Entfernung||Continuous noise level on the main road at night, Refrigerator at 1 m distance|
|Lern- und Konzentrationsstörungen möglich||Learning disorders and concentration problems possible|
|sehr leiser Zimmerventilator bei geringer Geschwindigkeit||Very quiet room fan at low speed|
|Atemgeräusche in 1 m Entfernung||Respiratory noise at a distance of 1 m|
|Abstand ca.||Distance about|
|raschelndes Blatt||Rustling leaf|
|tickende Uhr||Clock ticking|
|leise Musik||Soft music|
|normales Sprechen||Normal speech|
|schwerer Lkw||Heavy trucks|
Frequency is the number of waves or vibrations per second, and is measured in Hertz (Hz). Sound or noise is composed of many waves of different frequencies. Deep tones are low frequencies and high tones are high frequencies.
|Schalldruck in dB||Sound pressure|
|Zeit in sec.||Time in sec.|
|tiefer Ton||Bass (low-pitched) tones|
|hoher Ton||Treble (high-pitched) tones|
The mix of these frequencies in a sound can be represented as a frequency spectrum. The frequency spectrum of sounds that the human ear can hear falls between 20 and 20,000 Hz. Only the highest frequency range i.e. kHz to 4 is relevant to protecting against structural noise; humans’ ability to perceive frequencies in this range drops off markedly in either direction from this point. Sound insulation ratings, therefore, mainly take the range between 100 and 5000 Hz into account. The rating represents the fact that the human ear perceives high frequencies more readily than low frequencies into account and states it in terms of dB(A). “A” means adjusted. Defining sound reduction does not follow a linear path, but rather is a logarithmic function. Two sources of sound that are each 80 dB, for example, do not add up to 160 dB, but only to 83 dB. Thus, the human ear registers a difference of ± 10 dB as doubling, or cutting, the volume in half.
Generally, the following rating applies based on logarithmic assessments:
10 dB insulation = 50 % noise reduction
20 dB insulation = 75 % noise reduction
30 dB insulation = 87.5 % noise reduction
40 dB insulation = 94.25 % noise reduction
Since a large percentage of today’s installed soundproof glass insulation is rated for 40 dB, this type of glass only lets about 6% of external noise inside.
6.3 Sound ratings for buildings
A building component (e.g. glass) with a noise-reduction capacity rating of 40 dB will reduce the 70 dB of outside noise to 30 dB on the inside of the building, which is a noticeable reduction that is one sixteenth the outdoor noise level. When working with buildings, it is not possible to consider the building itself in terms of noise level. One must take the entire periphery around the building into account to get the total dB possible for sound reduction.
6.3.1 Medium noise reduction factor (RW)
The noise for solid objects is defined acc. to EN 20 140, EN ISO 717 and EN ISO 140, and is stated as Rw in dB. This is done by measuring and comparing a reference curve. Rw represents an average sound insulation over the relevant frequencies.
|Terzlärmpegel [dB]||One-third octave noise level [dB]|
|L außen||Noise outdoors|
|Innenpegel bei Standard-Isolierglas||Interior level in standard insulation|
|L innen||Noise indoors|
|Innenpegel bei Schallschutz-Isolierglas||Interior noise levels in insulating glass|
|Frequenz [Hz]||Frequency [Hz]|
|Schalldämmgewinn zwischen Standard-Isolierglas und Schallschutz-Isolierglas||Gain in sound insulation between the standard insulating type of glass and soundproofing insulation|
Here, the reference curve is moved vertically as long as the centre part of the underflow is not more than 2 dB. . Exceeding the curve is not considered. The value of the ordinates of the moved reference curve at 5,000 Hz complies then with the average assessed noise reduction value of Rw. Additionally, especially in Germany, DIN 4109 has to be considered. It defines follows the following nomenclaturea:
RW = assessed noise reduction extent in dB with no noise transfer over the adjacent components (just the net glass value, for example).
R’W = weighted sound reduction index in dB with sound transmission via adjacent structural components (for example windows)
R’W,res = resulting sound reduction index in db of the entire structural component (e.g. entire wall incl. Windows consisting of frames with glass and structural connections)
RW,P = weighted sound reduction index in dB, determined on the test station
RW,R = weighted sound reduction index in dB, calculation value
RW,B = weighted sound reduction index in dB, values measured on the construction
6.3.2 Correction factors (C, Ctr)
This statement can be used to compare and calculate individual acoustic components to arrive at the total sound level. However, real-life application has shown that, depending on the noise source for these Rw mean values, there are certain correction factors that must be taken into consideration, which are also defined in the EN.
|Geräuschquelle||Source of the noise|
|Spektrum-Anpassungswert||Spectrum adaptation value|
|Normale Frequenzgeräusche, wie Reden, Musik hören, Radio und TV||Normal frequency noise levels such as talking, listening to music, radio and TV|
|Spielende Kinder||Children playing|
|Schienenverkehr, mittlerer und hoher Geschwindigkeit*||The sound made by railcars moving at a average and high speeds|
|Autobahnverkehr über 80 km/h*||Highway traffic travelling at over 80 km/hr*|
|Flugzeuge mit Düsenantrieb in geringem Abstand||Airplanes using jet propulsion from a short distance|
|Produktionsbetriebe, die vorwiegend mittel- bis hochfrequenten Lärm abstrahlen||Production plants, which emit predominantly medium-to high-frequency noise|
|Spektrum 1||Spectrum 1|
|Innerstädtischer Straßenlärm||Inner city street noise|
|Schienenverkehr mit geringer Geschwindigkeit||The sound made by railcars moving at a slow speed|
|Flugzeuge mit Düsenantrieb in größerer Entfernung||Airplanes using jet propulsion from a great distance|
|Produktionsbetriebe mit vorwiegend tieffrequenter Lärmabstrahlung||Manufacturing companies with predominantly low-frequency noise radiation|
|Spektrum 2||Spectrum 2|
|* In verschiedenen EU-Ländern gibt es Rechenverfahren für die Fixierung von Oktavbandschallpegeln für Straßen- und Schienenverkehrsgeräusche. Diese können zum Vergleich mit den Spektren 1 und 2 herangezogen werden.||*In several EU countries, there are computational methods for the fixation of octave-width sound levels for road and rail traffic noise. These can be used for comparison with the spectra of 1 and 2.|
These correction factors, i.e. spectrum adaptation values C and Ctr, reduce the sound reduction index Rw of the component if the noise sources acc. to the EN list are causative. This means that a component with the values Rw (C,Ctr) = 40 (-2,-8) has an average insulating capacity of 40 dB, e. Especially for noise sources at higher pitches. However, the noise reduction is 2 dB lower, and mainly for those with lower frequencies, the reduction is even 8 dB lower.
6.4 Influence factors and production varieties
The following parameters affect noise reduction via glazing.
6.4.1 Weight of the pane
It generally follows that the thicker the pane per surface unit is, the greater the noise reduction. Therefore, insulation efficiency increases as glass thickness rises.
6.4.2 Insulating structure / Interspace
A two- or even three-paned insulating glass is a so called mass-spring-mass system: both outer panes (masses) are separated from each other by the air or gas that fills the interspace. The interspace muffles the vibrations from the outer pane before they reach the inner, second pane, with the rule being the. The bigger the interspace, the more effective the noise reduction. But this is only possible to a limited degree, since this process not only reduces thermal insulation (see > chapter 3.3) but also increases the climate’s impact on the unit. If you moderately increase the interspace with an asymmetrical insulating structure, the glazing will produce excellent noise reducing values.
|VON DOPPELSCHEIBEN||RW from dual-paned glass|
|GESAMTGLASDICKE||Total glass thickness|
|Veränderung des Scheibenzwischenraumes||Change in the interspace between the panes|
|Asymmetrischer Isolierglasaufbau||Insulating glass construction|
6.4.3 Decoupled single panes
The noise-reducing effect of thicker, heavier glass may be further optimized by using laminated film to connect two single panes of glass. With this solution, the thickness and space weight remain the same; the pane, however gets “softer” and thus increases its insulating capacity in terms of sound waves.
Special noise-protection films are also used nowadays in addition to the usual commercial PVB films that have been used utilized to produce laminated safety glass for many years. In addition to the safety aspect, they increase noise protection.
|Schalldämmmaß R[dB]||Measured sound reduction|
|8 mm Floatglas||8 mm float glass|
|Isolierglas aus 2 x 4 mm Glas||Insulating glass made from 2 x 4 glass|
|Frequenz [Hz]||Frequency [Hz]|
6.5. Basic rates for sound protection glass
The Guardian base line of products uses two different versions for manufacturing noise control products. The first version is for manufacturing laminated safety glass products that provide improved sound insulation because they are made using the proven polyvinyl butyral (PVB) (see > chapter 7.4).
Another improvement to the products is that standard films have been replaced with sound-optimized versions. Depending on the structural requirements of the building, you can choose between different types of glass since a wide range of functional glass is manufactured (see > Chapter 10).