The estimation of the noise impact caused by road freight transportation is critical to have acknowledgment of the ambiance pollution caused by road traffic crossing geographical areas containing important natural resources. Thus, our work proposes a within-subject survey where a Contingent Valuation Method (CVM) is combined with a laboratory economic experimental auction. Our study objective is to measure the willingness-to-pay (WTP) for reducing traffic noise nuisances due to freight transportation in the region of Navarre, Spain. A special focus is made regarding the measurement of the hypothetical bias, when a comparison is done between hypothetical WTP, coming from the CVM study, with real-incentivized one, as the outcome of the economic experiment. Additionally, statistical analyses are conducted in order to find explanation factors for these outcomes. Results suggest a strong evidence for an upward hypothetical bias (from 50% to 160%) indicating the income, the educational level, the gender, and the age as the main factors which explain that bias.

对道路货运引起的噪声影响的估计对于确认道路交通穿越包含重要自然资源的地理区域所造成的环境污染至关重要。因此，我们的工作提出了一项主题内调查，其中将权变估值法（CVM）与实验室经济实验性拍卖相结合。我们的研究目标是测量支付意愿（WTP），以减少西班牙纳瓦拉地区因货运引起的交通噪声滋扰。当比较来自CVM研究的假设WTP与真实激励的WTP作为经济实验的结果时，要特别关注假设偏差的度量。此外，为了找到这些结果的解释因素，进行了统计分析。结果表明有强烈的假设偏差（从50％到160％），表明收入，教育程度，性别和年龄是解释该偏差的主要因素。