Abstract: A simple and economical scale model experiment scheme is presented for evaluating and predicting the traffic noise impact in built-up areas. A real-time frequency analyzer is used in a 1:80 scale model to measure pulse spectra from a spark. It makes the experiment easy. The random mixed-vehicle free flow traffic in multilane street is simulated mathematically by a stream with negative exponential headway distribution and in which all vehicles move toward the same direction along the mean lane having the same noise impact function. The statistical sound parameters (L_eq and L₁₀) being analyzed and calculated in micro-computer are consistent with measurement data.