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Defining your noise problem: The first step to solving it

To define your specific problem, you need a basic understanding of how to quantify both your unwanted noise and the sound level that will be acceptable. The difference between those two values is the degree of sound control you need to achieve with your door opening. That understanding requires a brief overview of the science of sound and its measurement.

 

We begin with a few important definitions:

We begin with a few important definitions:

  • Sound is vibrations in air moving in waves. The rate of sound pulsations measured in cycles per second is called frequency—also known as hertz (Hz).  The range of human hearing is considered to be 20 to 20,000 Hz.
  • Sound pressure levels are measured in decibels—or dB. The scale of measurement used to simulate sound across the audible frequency range is denoted as dBA. Figure 1 illustrates the impact of dramatic changes in dB levels.  It is also important to note that the human ear perceives changes in loudness caused by even small changes in those levels. Each 10 dB increase doubles the sound reception—and the annoyance or discomfort that goes with it.

 

Comparison of sound pressure levels and loudness sensations

Sound pressure level (dBA)

Source

Sensation

130

Jet aircraft at 100'

Bass drum at 3'

Auto horn at 3'

Physical pain

120

 

110

 

Thunder, artillery, nearby riverter evevated train, discotheque

Deafening

100

 

90

Loud street noise, noisy factory

Track unmuffled,police whistle

Very loud

80

 

70

Cocktail party, noisy office, average street noise

Average radio, average factory

Loud

60

 

50

 

Noisy home, inside general office

Conversation, quiet radio

Moderate

40

30

 

Quiet home, private office

Empty auditorium, quiet conversation

Faint

20

Rustle of leaves

Very faint

10

Whisper, soundproof room

Very faint

0

Threshold of audibility

 

US Federal code prohibits exposure to noise levels which exceed these limits

Duration Hours Per Day

Sound Level in dBA

8

90

6

92

4

95

3

97

2

100

1-1/2

102

1

105

½

110

¼ or less

115

 

To go from definitions to practical applications, we first need to understand how sound is transmitted from its source through a barrier.  Next we will explain how a barrier is rated for its ability to inhibit or block sound. That gives us the ability to compare different barriers. With that information, we can examine the role of gasketing systems in optimizing the performance of doors that function as sound barriers.