Tapiola Lutheran Church in Espoo, Finland, Opened in 1965 Helmholtz-type resonators are built into the walls of the church. The slots between brick pairs and cavities behind them act as both absorbers and diffusors of sound. The absorption reduces the reverberation time as desired for… Read more
A sound file from the attack on the U.S. Embassy in Cuba has now been made available on the Internet. I did a spectral analysis of this file using my Matlab GUI scripts. The sound source is still unknown. The attacks have caused hearing, cognitive,… Read more
NASA SP-8072 Acoustics Loads Generate by the Propulsion System (Alternate SP-8072 link) The liftoff analysis has been added to the GUI package at: Vibrationdata Matlab GUI The function can be accessed via: >> vibrationdata > Miscellaneous Functions I > Acoustics Vibroacoustics & SEA > acoustics >… Read more
LA Times Article, Supersonic passenger jets might make a comeback, more than a decade after the last Concorde flight link Boom Technology Inc. – Tom Irvine
There are several tools for analyzing jet aircraft sound as measured on the ground. The measurements would typically be made for takeoff and final approach at or near an airport. Fly-over sound levels can also be recorded. The tools begin with the unweighted, one-third… Read more
A spacecraft at launch is subjected to a harsh acoustic and vibration environment resulting from the passage of acoustic energy, created during the liftoff of a launch vehicle, through the vehicle’s payload fairing. In order to ensure the mission success of the spacecraft it is… Read more
I recently flew as a passenger on a Boeing 717-200 aircraft similar to the one shown in the image. This aircraft has two Rolls-Royce BR700 engines, with the following specifications: Maximum Engine Rotational Speeds (Both Engines) N1 Low Pressure Turbine = 6,195 RPM (103 Hz) N2… Read more
Here is a paper showing how fatigue damage can be calculated from a stress response PSD for a plate excited by an acoustic pressure field: acoustic_fatigue_plate.pdf The calculation method is given at: Fatigue Damage for a Stress Response PSD * * * The Matlab scripts… Read more
This Webinar unit shows how to perform spectral analyses on sound files using the Matlab & Python Vibrationdata packages. PowerPoint File: Webinar_sound_files.ppt – Matlab & Python Audio/Visual File: NESC Academy Sound File Processing – Recommend viewing in Firefox with Sliverlight Plugin * * * The sample… Read more
I recently flew as a passenger in a CRJ-200 (aka CL-65) jet similar to the one shown in Figure 1. This aircraft has two General Electric CF34-3B1 turbofan engines, as shown in Figure 2. Here are the rotational speeds for each rotor. N1 Fan Speed… Read more