Effect of Combined Noise Sources on Cognitive Performance and Perceived Disturbance

 

Jin Yong Jeon - jyjeon@hanyang.ac.kr

Pyoung Jik Lee

Dept. of Architectural Engineering, Hanyang University

Seoul 133-791, Korea

 

Popular version of paper 2aNSb3

Presented Tuesday morning, April 20, 2010

159th ASA Meeting, Baltimore, MD

 

 

Noise is one of the most distracting factors in our environment. Environmental noise causes a variety of adverse effects such as annoyance, speech interference, and reduction of work performance. For this reason, there have been diverse studies of harmful noise effects, but most of these studies have dealt only with a single noise source. The effects of combined noise sources have rarely been investigated.

 

It is well known that noise impairs cognition. Recently, adverse effects of combined noise sources have been reported in terms of cognitive performance and perceived disturbance. People are exposed to various kinds of concurrent noise sources, such as air-conditioner noise, road traffic noise and noises from construction fields in their daily lives. Therefore, both single and combined noise sources should be considered in studies on the effects of noise on cognitive performance.

 

In this study, an experiment was conducted to investigate differences between the effects of individual and combined noise on cognitive performance and perceptions using free recall and word comprehension evaluation methods. The individual noise source was road traffic noise while combined noise was represented by construction noise played together with road traffic noise. Road traffic noise and construction noise were chosen to reflect the most common noise people are exposed to. Road traffic noise is almost constant, while the construction noise that causes the most frequent public complaints is impulsive, intermittent, and fluctuating. Road traffic noise was recorded from a six-lane road. The average velocity of the cars on the road was 60km/h. Impulsive hammering noise in a construction field was used as a construction noise source. The sound pressure level of the construction noise was varied from 30dB to 50dB as a step of 10dB and the road traffic noise was fixed to 35dB to represent an indoor environment.

 

The subjects were asked to recall presented words after exposure to noise (an episodic memory task) and to select a target word when five words, including the target word and other words, were presented simultaneously (semantic memory task). Subjects also rated the level of perceived annoyance and disturbance to the noise exposure during the experiment.

 

The result of the experiment indicated that only the retrieval task, which requires generating the internal cues, was affected by the level of combined noises. In contrast, the semantic memory task was not impaired by the level of construction noise. It is estimated that combined noise has more influence on performing intellectual work.