# Experimental Investigation of Task Performance and Human Vigilance in Different Noise Environments
## 1 Introduction  
Noise that is irrelevant to a task poses a risk to the working efficiency, safety, and personal health of operators [1]. Especially in a closed cabin environment, when operators are exposed to noisy environments for a long time, adverse reactions may occur to the cardiovascular system, nervous system, etc., and even increase the probability of operators suffering from diabetes and hypertension [2; 3; 4]. Most research has indicated that exposure to a harsh noise environment will interfere with an operator's task performance. For example, [PERSON] et al. [5] recruited 27 subjects to compare the impact of six noise exposure conditions on the task performance of operators. The results showed that there was a negative correlation between the task performance (accuracy and response time) of participants and noise exposure. [PERSON] et al. [6] investigated the effects of three kinds of noise conditions on attention and short-term memory. The results showed that performance in an environment with alarm sounds was low; that is, there was a high number of errors high and long response times. In addition, [PERSON] et al. [7] also evaluated the cognitive ability of 84 naval personnel exposed to noise. The test results showed that compared with personnel exposed to <72.6 dB(A), when the noise sound pressure level was >85.2 dB(A), the task performance of operators was significantly reduced. However, in other research reports, noise was shown to stimulate participant attention, improve vigilance and task participation, and improve task performance [8]. Moreover, relevant studies have found that the impact of noise on task performance could be related to task difficulty [9; 10; 11].  
Noise exposure may also affect human vigilance. Some scholars believed that when operators worked for a long time, they would become sleepy and inefficient, and that the addition of noise could improve the vigilance of operators [12]. However, [PERSON] et al. [13] indicated that response times to alertness tasks exposed to 95 dB(A) of noise was significantly longer than those exposed to 53 dB(A) of noise. The test results of [PERSON] [14] also showed that noise reduced the cognitive vigilance of operators. The psychomotor vigilance task (PVT) and Karolinska sleepiness scale (KSS) have been widely used to measure human vigilance performance. In addition, relevant literature has confirmed the consistency between the sample entropy (SampEn) of heart rate variability (HRV) and participant vigilance [15; 16]. SampEn was proposed by [PERSON] and [PERSON] [17], which has been shown to be an improved method for measuring the complexity of physiological time-series signals based on approximate entropy [18].  
Although there have been many studies on the effects of sound pressure level on task performance and vigilance, few studies have been conducted on the effects of other noise parameters, such as sharpness. The SampEn of HRV signals has also been less commonly used to assess noise effects on human vigilance from a physiological perspective. To address these issues, we used the Multi-Attribute Task Battery (MATB) with multiple workload levels and PVT to investigate the effects of sound pressure level and noise sharpness on task performance and human vigilance. The sample entropy of recorded HRV signals was further calculated to physiologically assess vigilance.