Much attention has been paid to the negative impacts of noise on individuals' health and well-being. Research extending back two decades or more has demonstrated repeatedly that prolonged exposure to certain types of environmental or ambient noise can increase stress, disrupt sleep patterns, hamper cognition, decrease productivity and eventually lead to serious physical health problems, such as hypertension and cardiovascular disease.

Yet we also know people are not affected by or do not respond to noise in the same way. What may be irritating noise for one person may be acceptable or even undetected by another. Two recent studies suggest why that may be, with implications for how designers might plan spaces to allow for subjective responses to noise.

How is it that persons who may complain of being subjected to excessive environmental noise in the workplace will choose the most "lively" bar or restaurant when going out after work, even though the noise level is equal to or much higher than that at work? Partly, of course, it is because the activities are different. It takes much less concentration and cognitive effort to have a conversation with friends over dinner or drinks than to perform one's work tasks.

In addition, researchers have found, what also matters is how one is disposed to perceive the sound. Is it wanted or unwanted, intrusive or not intrusive?

Say you are walking down the street talking with a friend and a bus goes roaring by. To continue the conversation, you will automatically start speaking louder. Scientists call this the "Lombard effect."

A team of researchers from New York University (NYU) and NYU Shanghai has discovered a similar adjustment takes place when we imagine ourselves speaking louder, such as when we think about how we might answer someone or prepare a talk in our heads.

The louder our thoughts, the more environmental noise recedes into the background, just like talking over the bus or the crowd in a bar. This helps to explain why someone thinking through a problem or absorbed in reading a document may "block out" environmental noise temporarily that otherwise would be perceived as irritating or distracting.

In another, unrelated study, researchers wanted to find out how the presence of noise impacted a farm community's willingness to have a wind turbine erected nearby. A common complaint is that the modulated sound waves produced by the turbines are an unrelenting annoyance that can make people irritable and disrupt their sleep.

One of the factors they examined was the distance of the turbine from the community. Quite unexpectedly, their data showed that while distance from the turbine was not a factor, whether the farmers felt they had been treated fairly or not in negotiations as to where to place the turbine did matter.

When engaged in the planning process (i.e., when the noise was not imposed on them or wholly unwanted), the study found, residents reported being less stressed and less bothered by the noise from the turbine. The researchers conclude, "The planning and construction process has proven to be central — it is recommended to make this process as positive as possible."

Designers frequently must seek a balance between meeting a client's needs and specifications for a space and minimizing the level of ambient and environmental noise that may affect occupants' health and well being. These two studies suggest that in seeking suitable compromises, designers should involve occupants in determining what are acceptable conditions, whether for work, entertaining or socializing.

Furthermore, when establishing quiet zones for heads-down, cognitive activity, it may be sufficient to deflect intrusive background noise rather than block it out altogether.