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所在平台: Udemy |
课程主页: https://www.udemy.com/course/acoustics/
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**课程名称：声学：声音的奥秘 (Acoustics: Sounds Right)** **课程概述：** 本课程将带您深入探索声音的物理学原理——声学。我们将从最基础的正弦波、声音在介质中的传播、粒子运动、声速、波长与频率等方面入手，逐步深入理解复波、谐波、相位、泛音、倍频程、频谱，以及电、机械和声学类比。 随后，课程将重点讲解声音的级别和分贝（dB）的应用，包括比率与差异、对数概念、不同参考电平下的分贝计算，以及声功率、声压级、扬声器和麦克风的规格，还有功放、音乐厅等实际场景中的分贝应用，并通过实例学习如何组合分贝和测量声压级。 接着，我们将考察自由声场中的声音传播，包括自由场的定义、声音的扩散、声强和声压在自由场中的变化，以及在封闭空间中的声场和半球形传播。 课程的“声音感知”部分将详细解析人类的听觉系统，从耳廓、耳道到中耳和内耳的结构，特别是内耳中的毛细胞（Stereocilia），并探讨响度与频率、响度控制、听阈、响度与声压级的关系，以及响度、带宽、冲激声响度、响度变化的可闻性。还会深入研究音高与频率的关系、缺失基频、音色与频谱的联系、声源定位（包括双耳定位、首波定律、Franssen效应、前导效应），以及对反射声的感知，如鸡尾酒会效应、听觉非线性、主观与客观的区别，并提及职业性和娱乐性造成的听力损失。 在“信号、语音、音乐与噪声”部分，我们将学习声谱图，剖析语音的形成（声道塑造、发声原理、不发声原理）、语音的频率响应和方向性，以及音乐的特点，包括弦乐器、管乐器、非谐波泛音、语音和音乐的动态范围、功率、频率范围和听觉区域。此外，还将探讨噪声（测量、随机噪声、白噪声与粉红噪声）、信号失真（谐波失真）和共振，以及音频滤波器。 最后，“反射”章节将深入研究各种反射现象，包括镜面反射、颤动回声、压力倍增、凸面、凹面和抛物面反射，以及耳语廊、驻波、角反射器、平均自由程。我们将学习声音反射的感知，单次反射的效果，空间感的形成，以及图像和回声，并分析入射角、信号类型和频谱对反射声可闻性的影响。 通过本课程的学习，您将能够更深入地理解声音的本质，并掌握相关的测量和分析方法，甚至可以在您“配偶对您大喊大叫”时，准确测量出“令人不满的信息携带声音”的频率和振幅。
All of us speak and hear people blabber every day [Sigh...]. Those of us who are lucky also listen to music every day and some of us even play music. However, very few understand the theory behind music and sound. Let me blow your mind and take you on a journey into Acoustics - a branch of physics concerned with the properties of sound.Let us dive deep into the human ear and brush against the Stereocilia. By the end of this course you will know how to measure the exact frequency and amplitude of sound when your spouse yells at you, which we will term "objectionable information carrying sound". More specifically: In section 1: "Fundamentals of Sound" we will explore The Sine Wave, Sound in Media, Particle Motion, Propagation of Sound, Speed of Sound, Wavelength and Frequency, Complex Waves, Harmonics, Phase, Partials, Octaves, Spectrum, Electrical, Mechanical, and Acoustical Analogs. In section 2: "Sound Levels and the Decibel" we will explore Ratios versus Differences, Expressing Numbers, Logarithms, Decibels, Reference Levels, Logarithmic and Exponential Forms Compared, Acoustic Power, Using Decibels, Sound-Pressure Level, Loudspeaker SPL, Microphone Specifications, Line Amplifier, General-Purpose Amplifier, Concert Hall, Combining Decibels, Measuring Sound-Pressure Level, and Sine-Wave Measurements. In section 3: "Sound in the Free Field" we will explore The Free Field, Sound Divergence, Sound Intensity in the Free Field, Sound Pressure in the Free Field, Examples: Free-Field Sound Divergence, Sound Fields in Enclosed Spaces, and Hemispherical Field and Propagation. In section 4: "The Perception of Sound" we will explore Sensitivity of the Ear, Ear Anatomy, The Outer Ear, Directional Cues, The Ear Canal, The Middle Ear, The Inner Ear, Stereocilia, Loudness versus Frequency, Loudness Control, Area of Audibility, Loudness versus Sound-Pressure Level, Loudness and Bandwidth, Loudness of Impulses, Audibility of Loudness Changes, Pitch versus Frequency, Pitch, The Missing Fundamental, Timbre versus Spectrum, Localization of Sound Sources, Binaural Localization, Law of the First Wavefront, The Franssen Effect, The Precedence Effect, Perception of Reflected Sound, The Cocktail-Party Effect, Aural Nonlinearity, Subjective versus Objective, and Occupational and Recreational Deafness. In section 5: "Signals, Speech, Music, and Noise" we will explore Sound Spectrograph, Speech, Vocal Tract Molding of Speech, Formation of Voiced Sounds, Formation of Unvoiced Sounds, Frequency Response of Speech, Directionality of Speech, Music, String Instruments, Wind Instruments, Nonharmonic Overtones, Dynamic Range of Speech and Music, Power in Speech and Music, Frequency Range of Speech and Music, Auditory Area of Speech and Music, Noise, Noise Measurements, Random Noise, White and Pink Noise, Signal Distortion, Harmonic Distortion, Resonance, and Audio Filters. In section 6: "Reflection" we will explore Specular Reflections, Flutter Echoes, Doubling of Pressure at Reflection, Reflections from Convex Surfaces, Reflections from Concave Surfaces, Reflections from Parabolic Surfaces, Whispering Galleries, Standing Waves,The Corner Reflector, Mean Free Path, Perception of Sound Reflections, The Effect of Single Reflections, Perception of Spaciousness, Images, and Echoes, Effect of Angle of Incidence, Signal Type, and Spectrum on Audibility of Reflection.
