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Basics of Noise and its Measurements

Basics of Noise and its Measurements. Instructor: Prof. Nachiketa Tiwari, Department of Mechanical Engineering, IIT Kanpur. This course is intended for all those who want to conduct experiments in area of NVH. Thus, the course is open to students of engineering and science, and also to all those who from the industry and research organizations - who are working in area of sound, NVH and acoustics. Each lecture will be followed by a quiz, which will help student the concepts better, and gain deeper insights to measurement process. The course is fairly generic so that there is no need for a particular background. Rather, what is needed is openness, and ability to learn and check out new ideas with comfort. (from nptel.ac.in)

Lecture 35 - Fast Fourier Transform (FFT) and Inverse FFT

Go to the Course Home or watch other lectures:

Lecture 01 - Introduction

Lecture 02 - Vibration versus Waves

Lecture 03 - Nature of Sound

Lecture 04 - The Decibel Scale

Lecture 05 - Sound Terminology

Lecture 06 - Adding Decibels

Lecture 07 - Modeling Sound Propagation

Lecture 08 - The Momentum Equation

Lecture 09 - The Continuity Equation and the Gas Law

Lecture 10 - 1-D Wave Equation

Lecture 11 - General Solution for 1-D Wave Equation

Lecture 12 - Complex Time Signal and Transfer Functions

Lecture 13 - Transmission Line Equations

Lecture 14 - Planar Waves in Closed Tubes

Lecture 15 - Planar Waves in 1-D Open Tubes

Lecture 16 - A Semi-infinite Tube and Overall Summary

Lecture 17 - 1-D Tubes with Imperfect Terminations

Lecture 18 - Measuring Impedance Through Kundt's Apparatus

Lecture 19 - Classification of Microphones

Lecture 20 - Classification of Microphones (cont.)

Lecture 21 - Classification of Microphones by Application

Lecture 22 - Microphone Sensitivity

Lecture 23 - Microphone Sensitivity (cont.)

Lecture 24 - Selecting the Right Microphone

Lecture 25 - Fourier Series Expansions

Lecture 26 - Fourier Series Expansions (cont.)

Lecture 27 - Fourier Integral

Lecture 28 - Fourier Integral (cont.)

Lecture 29 - Fourier Transform

Lecture 30 - Fourier Transform (cont.)

Lecture 31 - Discrete Fourier Transform (DFT)

Lecture 32 - Discrete Fourier Transform (cont.)

Lecture 33 - DFT: Calculating Frequencies and Padding

Lecture 34 - DFT: Influence of Duration and Sampling Frequency on Resolution

Lecture 35 - Fast Fourier Transform (FFT) and Inverse FFT

Lecture 36 - Considerations while Deciding Instrumentation

Lecture 37 - Considerations for Selecting Instruments for Noise Measurements

Lecture 38 - Measuring Impedance using the Two Microphone Method

Lecture 39 - Designing an Impedance Measurement Tube

Lecture 40 - Octave Band Analysis

Lecture 41 - Calculating Results in Octave Bands

Lecture 42 - Weighting

Lecture 43 - Short Time DFT

Lecture 44 - Short Term Fourier Transforms and Spectrograms

Lecture 45 - Reverberation Time

Lecture 46 - Anechoic Rooms

Lecture 47 - Sound Transmission Class, Noise Reduction Coefficient, Sound Attenuation

Lecture 48 - Reverberant Room