摘 要

在交通方式不断进步的现代化社会，人们每天出行越来越离不开汽车。一方面汽车缩短了出行时间，提高了出行效率；另一方面为人们出行的舒适性提供保证。然而在这些优点的背后，由汽车衍生出的环保问题也日益严峻。其中噪声污染问题是如今国际上重点研究的问题之一，也是目前亟待解决的课题。汽车噪声大半来自于发动机，而作为发动机的动脉，进气系统噪声在整个汽车噪声中占有举足轻重的地位。因此，了解研究进气噪声并对其进行调控非常必要。本文结合目前国内外对噪声的研究现状，利用现代计算机技术，同时将理论运用于实际，设计出能对进气噪声进行阶次分析调制合成的软件，这对于实现进气噪声的选择性控制具有重要意义。

首先，本文阐明了对进气噪声分析控制的意义，论述了当今国内外关于噪声的研究现状。另外，从进气噪声的产生原理及主要组成入手，详细介绍进气系统产生进气噪声的整个过程并在该过程中分别产生的噪声成分，进一步加深对进气噪声的理解。具体从客观与主观两个方面介绍进气噪声的评价标准，使得能够更准确把握进气噪声的研究控制尺度。本文还从实际出发，通过具体的进气噪声样本采集试验获得原始样本信号。

之后，在阶次分析理论的层面上，建立阶次追踪算法模型。对原始噪声样本进行阶次追踪，详细介绍了阶次追踪主要过程，包括采样、滤波、插值重采样、加窗等。再通过傅里叶变换得到阶次谱，计算噪声信号的主阶次和谐阶次的声压级，最终得出相应的各阶次曲线图。

最后，简单说明 MATLAB软件的功能，同时介绍其中的GUI模块。对已经提取的噪声阶次进行调制和合成，改变其特定转速内声压级并生成新的声音样本。利用MATLAB中的GUI模块，建立阶次调制软件，并逐一介绍其中各个模块的功能，最终得出调制后的阶次曲线。

研究结果表明：运用阶次追踪和提取技术可得到噪声样本的阶次曲线图，可以更加直观的看出不同阶次在进气噪声中的比例以及各自随转速的变化趋势，进而可以在任意转速范围内调整各个阶次的声压级。

本文的特色：将阶次调制技术与MATLAB的GUI模块结合，实现对进气噪声的可视化阶次调制并设计出相关软件，为进气噪声的选择性控制提供更加便利的操作。

关键词：进气噪声；阶次追踪；阶次提取；声压级；MATLAB；GUI；选择性控制

Abstract

In the era of rapid development of the automobile industry, automobiles have brought many problems while bringing people convenience. The problem of car noise pollution is one of the world's current problems, and it is also a problem that needs to be solved urgently. The noise of the car mainly comes from the engine. As the artery of the engine, the noise generated by the intake system plays an indispensable role in the noise of the entire car. Therefore, it is necessary to analyze and control the intake noise. This graduation project will combine the current research status of noise at home and abroad, use modern computer technology, and apply the theory to practice at the same time, to achieve order analysis and selective control of the intake noise by the software.

First of all, this paper introduces the research significance of the analysis and control of the intake noise and explains the research status at home and abroad. In addition, starting from the principle and major components of the induction noise, we will introduce in detail the entire process of the intake system noise generation and the noise components generated in the process, further deepen the understanding of the intake noise. Objectively and subjectively explain the evaluation index of the intake noise, which provides a reference for the direction of the intake noise control. This article also starts from reality and obtains the original sample signal through a specific intake noise sample acquisition experiment.

Secondly, based on the theory of NVH order analysis, a model of order tracking algorithm is established. The order of the original noise samples is traced, and the main process of order tracking is described in detail, including sampling, filtering, interpolation resampling, and windowing. Then the Fourier transform is used to obtain the order spectrum, and the sound pressure levels of the main order and harmonic order of the noise signal are calculated, and finally the corresponding order curves are obtained.

Finally, sufficient theoretical preparations are made for the implementation of the intake noise modulation software: simply explain the function of the MATLAB software and introduce the GUI module. Modulate and synthesize the already extracted noise order, change the sound pressure level within its particular rotation speed and generate new sound samples. Using the GUI module in MATLAB, the order modulation software is established, and the functions of each module are introduced one by one. Finally, the order curve after modulation is obtained.

Research results show that using order tracking and extracting technology available noise sample order curve, can be more intuitive see the proportion of different order in the intake noise and their trend along with the change of rotating speed, so that can at any speed within the range of changes to the order of the sound pressure level.

The article features: It will combine order modulation technique with MATLAB GUI module, to get the visualization system for the intake noise order modulation and design the related software, for the selective control of air intake noise to provide more convenient operation.

Key words:intake noise; order tracking; order extraction; sound pressure level: MATLAB; GUI; selective control

目 录

摘要 I

Abstract II

第1章 引言 1

1.1 研究课题的背景与意义 1

1.2 对噪声问题的研究现状 1

1.2.1 国内研究现状 1

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