1: Fundamentals
- Page ID
- 134530
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 1.1: Fundamentals of Acoustics
- This page offers a concise overview of sound wave propagation in homogeneous fluids, detailing sound as pressure oscillations through media governed by the wave equation, derived from conservation and thermodynamic principles. It covers key concepts such as the Helmholtz equation, acoustic intensity, and decibels for sound measurement.
- 1.2: Fundamentals of Room Acoustics
- This page outlines three primary theories of room acoustics: modal theory, which addresses acoustic modes in simple geometries; geometric theory, suited for larger spaces and reliant on computational intensity; and Sabine's theory, emphasizing practical applications by associating acoustic energy changes with absorption and source power, highlighting reverberation time's dependence on room volume and absorption area.
- 1.3: Fundamentals of Psychoacoustics
- This page explores the principles of psychoacoustics, highlighting the logarithmic nature of sound perception. It introduces terms like phons and sones to measure loudness, demonstrating that perceived loudness varies with the same intensity. Key parameters such as dB A, tonality, roughness, sharpness, and the blocking effect are defined to enhance the understanding of sound sensations and their subjective experiences.
- 1.4: Sound Speed
- This page explains the speed of sound, which varies by medium and is primarily influenced by temperature, with specific formulas for gases and considerations for solids and fluids. Sound speed in water averages around 1500 m/s and is affected by salinity and depth. It also introduces Mach number as the ratio of an object's speed to sound speed, and details various experimental methods for measuring sound velocity in air, including timing techniques and resonance experiments.
- 1.5: Filter Design and Implementation
- This page summarizes the principles and designs of acoustic filters, specifically mufflers and Helmholtz resonators, highlighting their roles in sound attenuation. It distinguishes between absorptive and reactive mufflers, detailing their performance across frequency ranges and metrics like Noise Reduction and Transmission Loss.
- 1.6: Flow-induced Oscillations of a Helmholtz Resonator
- This page covers flow-excited acoustic resonance in Helmholtz resonators, including its applications in reducing sunroof buffeting in vehicles. It explains the lumped parameter model and the relationship between fluid motion and pressure oscillations that lead to passenger discomfort.
- 1.7: Active Control
- This page covers the principles of active noise control using destructive interference to reduce sound, especially effective at low frequencies. It describes two main techniques: feedforward, which targets specific sounds with known sources, and feedback, which reduces all sounds but complicates communication. The page highlights the challenges of noise control in ducts and emphasizes the role of psychoacoustics in perceived sound quality.