2D-FFT Analysis in MATLAB
2D-FFT can be a really powerful tool in identifying the propagation of different Lamb wave modes in a signal. The process was pioneered by Alleyne and Cawley (1990), and has since been used for a wide range of applications. In this post I will explain how 2D-FFT can be implemented in MATLAB, and how the results can be compared against dispersion curves.
Plotting Audio Data With R & Plotly
Disclaimer: This guide is written for Windows users however all tools are also available for Mac and Linux.
Presenting data in an aesthetically pleasing way can be difficult, there are many different tools available for creating graphs and plots but many of the best are challenging to learn, expensive, or both. This post will show you a way of using the free R programming language along with the graphing service Plotly to create high quality plots, specifically when dealing with audio data.
Time Domain Plots
Below you will find examples for plotting: Short audio clips (~1s) Time domain plot short.r Audio 0.8s.wav Long audio clips
FFT From A WAV File
Download the example script and audio file here. This example builds upon the script used in the time domain example. R
Loudspeaker Directivity Plots
Download example script and excel file here. A loudspeaker directivity plot shows frequency response as a function of directivity, allowing
Microphone Polar Plots
Download example scripts and data files here. In this example we will plot some idealised polar patterns followed by some
Tutorial: Measuring Reverberation Time – Part 2 – Deconvolution
In our previous reverberation time measurement tutorial an impulse response, created by bursting a balloon, was used as the measurement signal. This is a quick and simple method of carrying out a reverberation time measurement, but may not be the most accurate method. In this tutorial we will look at an alternative method that can provide improved results.
Tutorial: Measuring Reverberation Time
The reverberation time of a room has a distinct effect on its suitability for different tasks, in this tutorial we will look at the different methods of measuring reverberation time and what the results can show us.
The first step in carrying out a reverberation time measurement is choosing the method. There are a number of different methods available to us however some will require specialist equipment that the average person will not have access to (look out for follow up tutorials for these!). The simplest method involves creating and recording an impulse response.