As part of our commitment to a safe work environment for our employees, we train all new hires in the basics of sound and noise, how they work, and how they can protect themselves while working in loud environments, such as a data center. Since many of our colocation clients visit our data center to work on their servers/equipment, we thought it would be a good idea to do an article outlining some of the basics so that our clients can also be informed and protected when they come to visit us.
First, we’ll start with some key terms and their definitions.
Sound is the physical phenomenon that stimulates our sense of hearing. It’s an acoustic wave that results when a vibrating source, such as machinery, disturbs an elastic medium, such as air. The frequency (designated by “f”) is the number of vibrations, or complete cycles, that take place in one second. The wavelength (designated by “l”) is the distance traveled by a sound wave during one sound pressure cycle.
Decibels (designated by “dB”) is a unit of measurement for a variety of sound quantities. Something interesting to note is that decibels are logarithmic values, so they are not added by normal algebraic addition. For instance, 70dB plus 73dB does not equal 143dB, but rather 75dB. This is because the difference between the values is 3dB, so add 2dB to the higher value: 73+2=75dB (10Log10(70+73)).
Loudness is the subjective human response to sound, and it’s dependent upon sound pressure and frequency. The audible frequency range for young adults with good hearing is about 20 Hertz to 20,000 Hertz. The human ear is more sensitive to high-frequency sounds (sounds in the range of 2,000 to 8,000 Hertz) than it is to low-frequency sounds. Most people lose sensitivity for the higher-frequency sounds as they grow older.
Noise-induced hearing loss is incredibly pervasive, but it is very often ignored or overlooked because there are no visible effects. It usually develops over a long period of time, and it can manifest itself as a progressive loss of communication, socialization, and responsiveness to the environment.
OSHA, the Occupational Safety and Health Administration, publishes a chart of time-weighted averages for noise exposure that it recommends people not exceed. Short bursts of relatively loud noises are unlikely to cause long-term hearing damage, but sustained exposure to loud noises can certainly cause hearing problems. OSHA says that the maximum permissible exposure level (PEL) is a time-weighted average (TWA) of 90dB for 8 hours, 100dB for 2 hours, or 115dB for 15 minutes. To put that in perspective, when noise levels are above 80dB, people have to speak very loudly to hear or understand each other. At levels between 85 and 90dB, people have to shout to be heard. At noise levels greater than 95dB, people have to move very close together to hear each other at all.
While there are no circumstances that QuadraNet is aware of in which an employee or visitor might be subject to actionable levels of noise exposure, QuadraNet provides two forms of protection that are available to both employees and visitors in our 24x7x365 Network Operations Center (NOC) in suite 901 in our Los Angeles facility. The two types of hearing protection QuadraNet provides are 3M Tekk ear plugs and Pyramex PM5010 folding ear muffs, and we highly recommend that if you plan to be spending a fair amount of time working inside the data center, that you take precaution and use hearing protection.