Lesson 1

Background Noise: Why Is It A Serious Problem?

If you ask some acoustic consultants what common problem they often deal with, we are pretty sure that one of the answers is noise. If you are a city-dweller, you can find noise almost everywhere. You may hear the sound of annoying car horns from the bustling street just a few feet away from your office building. During your commute, you may encounter some road works with very unpleasant noise from the drilling machines. Even when you are already home and hope you will no longer hear any noise. You may be wrong. Cause once your neighbors are binge-watching Netflix, say goodbye to your relaxing and peaceful evening.

Noise: A subjective matter

But before you learn how to solve this problem, you need to understand what noise actually is.

In engineering, we often borrow the definition of noise according to the International Electrotechnical Commission (IEC). Under IEC 801-21-13, noise is defined as any disagreeable or undesired sound or other disturbance.

You may wonder why the definition of noise seems so subjective. The answer is … because it actually is subjective. That’s why acousticians often conduct a survey to investigate what kinds of noise their clients actually want to get rid of. However, acoustic consultants also need to deliver some recommendations to the clients on what noise that needs to be addressed. It is because people are oftentimes not aware that noise with whom they live is so harmful to their health.

In most projects, the primary focus of noise treatment is often the reduction of background noise levels. Background noise or ambient noise is any noise that can be heard continuously at a given location and time and measured in the absence of intermittent noise and any other extraneous noise.

For better understanding, we will give you an example. Imagine you are in an office room trying to get your work done before the deadline. What sound that gets on your nerves? You may feel irritated hearing the continuous buzzing sound from the HVAC equipment. Or the high-pitched squealing sound from the photocopy machine. Or even the hateful judgments from your colleague–well we hope there aren’t any. However, you may seem okay with the sound of other people talking and footsteps. The noise coming from the HVAC equipment is what we call as the background noise. Meanwhile, the sound generated by the photocopy machine can be considered as the intermittent noise.

Negative Effects of Background Noise

Everyone would agree that background noise cause annoyance. Some studies suggest that noise can be detrimental to our health and can reduce our productivity. Here, we will discuss the adverse effect of the elevated background noise of which you may be not aware in your daily life.

It impairs work productivity

Numerous studies have agreed that uncontrolled background noise can lower our performance at work.

A study conducted by the Buffalo Organization for Social and Technological Innovation (BOSTI) has found that 65% of the open office plan workers surveyed feel that they are distracted by noise.

Figure 1. Many office workers feel distracted by noise. (seventyfourimages, Envato)

An interesting study by Ising et al. from the German Federal Institute for Occupational Safety and Health shows that the reduction of background noise level from 41 dB(A) to 35 dB(A) resulted in a decrease in the word processing errors by 52%. For you who don’t know what dB(A) is, it’s the unit for sound pressure level. Don’t worry! We will discuss this in the next lesson.

It harms our wellbeing 

Hearing impairment due to occupational noise has been intensively researched by many scientists. Many countries have published their own regulation to limit exposure to noise in the workplace. So, keep an eye on the regulation where your project takes place.

Masterson et al. have carried out a study to show a significant difference in hearing loss between two groups of workers. The finding indicates that 23% of American workers who are exposed to noise have hearing loss. It is significantly higher than those who aren’t (only 7%).

Most of the hearing damages are irreversible, and the severity will increase with continued exposure. Luckily, this health concern is mainly preventable. One of the mitigation strategies is by implementing building acoustic proper design in the first place.

If you are an office worker, you have to be more grateful. Background noise in offices rarely leads to hearing impairments. However, it doesn’t mean there is no risk to your health. 

Published in Noise Health Review in 2003, Babisch et al. showed that there is a correlation between noise and cardiovascular risk. Elaborated further by Munzel et al. in the European Heart Journal, 2014, exposure to noise leads to an increase in the development of cardiovascular risk factors, facilitated by mental and physiological stress.

In other word, background noise can kill you. You can’t hide unless you fight it. In Europe alone, it kills 600 people per day, according to a review of a paper in the Journal of the American College of Cardiology.

It reduces speech intelligibility & sound quality

Do you know that you need to raise your voice 4 times higher than the background noise in order to be heard? There will be so much effort even to say a sentence to your colleague when the background noise level is fairly high. When it happens in the workplace, you can imagine how unconducive it will be.

In factories, you may see that some people are using earplugs or noise-canceling headphones. Yes, it can prevent hearing impairment. However, this protection could lead to other consequence, and that is a decrease in speech intelligibility. Hearing protectors like those can impair the audibility of warning signals and other critical verbal instructions that could cause work accidents. In places where safety concern is the top priority, noise reduction should more focus on the source or transmission.

When background noise present in a concert hall or another venue, it can interfere with the performance causing lower sound quality. Venues that are located in the city center are mostly a few meters away from the streets. With proper treatment, it can block the noise from coming in.

Figure 5. Noise can lower sound quality in concerts (NomadSoul1, Envato)

Even though we mainly talk about background noise here, it doesn’t mean that you shouldn’t worry about the intermittent noise. Some intermittent noise may need to be taken into account due to either its severity or the client’s request to tackle.