Health and Safety Considerations Regarding Exposure to Sound

Before we cover health and safety issues, there are some important background information to consider.

As you have already gathered in previous parts of this manual, your sense of hearing depends on a complex and delicate set of organs. They can tolerate loudness for an amount of time without causing discomfort, irritability and permanent physical damage to your ears.

Generally, humans can perceive sounds within a frequency range of 20Hz to 20KHz. But there are outliers that can hear frequencies as high as 24KHz. On the other hand, sub bass frequencies or sounds below 60Hz, while generally inaudible, can be physically felt. If you own or have used speaker systems with subwoofers, say in a car or theatre system, these are the frequencies that they emphasize.

The human ear can safely tolerate the softest audible sound, called “0” dB sound pressure level (SPL). Sounds below 85 dB are considered safe in the sense that they generally won’t inflict permanent damage to your hearing. You can tolerate well beyond that 85 dB for limited periods, though. The loudest sound tolerable is usually considered to be 120 dB SPL. Traditionally, 120 dB SPL is considered the threshold of pain. This means going past 120dB can result to legitimate pain and damage to your sense of hearing. However, the realities we experience today have made high SPL’s more commonplace, and has perhaps made people more tolerant, or at least more accustomed to being subjected to loud noises. This poses the argument that perhaps today, 140dB is now considered the threshold of pain.

We must, however, note that the issue is a lot more complicated than simply setting a single boundary between what leads to pain and what does not. There are prescribed doses or duration of exposure to sound or noise according to dB levels. The United States of America’s Center for Disease Control and Prevention (CDC) has a set of standards for the safety and welfare of workers. The table below shows two metrics. First is the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limits (REL). The second gauge is the Occupational Safety and Health Adminsitrations (OSHA) permissible exposure limits (PEL). Both gauges are measured in terms of what is called a time-weighted average. As you can see, the two gauges scale differently. The NIOSH REL was devised from the standpoint of what are considered best practices in the workplace. The OSHA PEL, on the other hand, are the levels which workers are legally allowed to be exposed to. In any case, both provide clear ideas of how much noise or loudness a human can tolerate or should be allowed to tolerate.

Time to reach 100% noise doseExposure level per NIOSH RELExposure level per OSHA PEL
8 hours85 dBA90 dBA
4 hours88 dBA95 dBA
2 hours91 dBA100 dBA
1 hour94 dBA105 dBA
30 minutes97 dBA110 dBA
15 minutes100 dBA115 dBA

To get a better appreciation of the above levels, below is a list of things or activities you commonly see and hear and how loud they typically are.

SoundLoudness (dB)
Rustling leaves20
Quiet whisper (3 feet)30
Quiet home40
Quiet street50
Normal conversation60
Loud singing (3 feet)75
Motorcycle (30 feet)88
Chainsaw (3 feet)117
Jet plane (100 feet)130

The big question that ought to be raised from all the above is obvious — So what?

What are the consequences of being subjected to noise beyond whatever is considered the threshold? From a production standpoint, it will be a lot more difficult to isolate sounds that you want to record, as you will find out later on. But looking at the broader picture, there are far serious problems that entail excessive noise. When we talk about environmental issues, the first things that come to mind would be climate change, deforestation, loss of biodiversity, waste management, water and air pollution. People can come up with a list of three or five issues. But I would bet that majority of people will not have noise pollution in their list of five.

Being subjected to more noise means a higher impact to the environment, as well as human health and safety. The video below is one of many resources that you can find that covers the effects of noise pollution. The video largely references the reality in New York City. However, the same problems are likely to be present in other highly urbanized areas, including Metro Manila.