What Are dB, Noise Floor & Dynamic Range?
We are often asked what noise floor & dynamic range actually are. Most engineers are probably familiar with or have come across the decibel or dB as a unit of…
Electric Vehicles – Vibration & Acoustic Testing
Electric vehicle noise & vibration testing is crucial for vehicle development, ensuring the final product’s comfort, safety, and reliability. While electric vehicles (EVs) and internal combustion engine (ICE) vehicles undergo…
5 Cool Acoustics Links
We have scoured LinkedIn, Twitter and the rest of the Internet to find these cool acoustics links. And since two of them are themselves lists of 10 you're actually getting…
Sound, Vibration & Acoustics Digest #7
Chip/crisp packets, smartphones, the spooky sounds in space and the absolutely fascinating Diana Deutsch Speech to Song Illusion; welcome to our latest digest Extracting audio from visual information https://newsoffice.mit.edu/2014/algorithm-recovers-speech-from-vibrations-0804Algorithm recovers…
What engineering decisions are made by measuring a power spectrum?
By power spectrum we are talking about an ASD (Auto Spectral Density) or PSD (Power Spectral Density). In fact PSD is often used when really ASD would be more correct.
Taking any signal and performing a frequency analysis using an ASD or a PSD will give the energy over a range of frequencies. (more…)
Sound, Vibration & Acoustics Digest #1
This is the first in a (hopefully) regular series of posts containing interesting & unusual sound & vibration stories that we have discovered around the web. We hope you enjoy…
How to set up scheduled data captures
A video that explains how to set up the DATS Data Acquisition software to perform captures at specific, scheduled times. https://www.youtube.com/watch?v=jeJ6a0U9vjk
Why is the microphone pressure reference 2*10^-5 Pascals?
This seemingly simple question is actually quite fundamental. To answer the question we need to consider sound intensity. Now sound intensity is defined as “the average rate of flow of…
Measuring Torsional Vibration 101
Are you interested in measuring torsional vibration? Need to measure shaft twist? Worried about rotational jitter? Don't worry, we've got it covered. Here we have gathered together our most popular…
What’s All The Noise About?
We've come across a number of great noise related resources lately. So, rather than keep them all to ourselves, we have decided to share them with our readers. Thanks should…
What is Synchronous (Angular) Sampling?
The term synchronous data is usually applied to vibration or acoustic data that is captured from an item of rotating equipment at regularly spaced angle intervals as distinct from regularly spaced time intervals. The rotating part could be an engine, a gear wheel, a drive shaft, a turbine rotor, a propeller, a turbocharger or any other type of rotary mechanical device. Typically these items are subjected to out-of-balance forces that cause them to vibrate at frequencies that are multiples of the fundamental (once per revolution) rotation speed frequency. (more…)
5 Unusual & Interesting Acoustic Webpages
Many of our readers spend their days studying or solving noise problems. In our day-to-day work it’s often easy to forget some of the more unusual applications and miss out on the more interesting side of acoustics. So we have gathered together 5 examples of unusual or interesting acoustic work. If you know of any other out of the ordinary acoustic applications or websites then please leave a comment in the box at the end of this post. (more…)
Prosig’s Australian Agent Will Be Exhibiting At Acoustics 2011
Prosig's Australian agent, ETMC Technologies, will be exhibiting at Acoustics 2011, the Conference of the Australian Acoustical Society. The conference runs from 2-4 November 2011 at Holiday Inn, Surfers Paradise, Gold…
Do You Need To Measure Brake Noise?
The objective of the brake noise tests was to record the braking events of cars being driven on various types of road and classify those events according to their type (Groan, Creep or Squeal etc) and severity. To do this the customer needed a system capable of working for long periods inside a vehicle in fairly tough conditions (high ambient temperatures, rough road) that was both quick to install and to remove.
On previous tests a system from another supplier had turned out to be unreliable and had failed to cope with the harsh environment. The analysis processing had also proved tedious and time consuming due to the huge amount of data created when testing several vehicles over many days.
10 Outstanding Noise, Vibration And Acoustics Videos
For our latest collection of videos we’ve searched for the most interesting examples of noise, vibration and acoustic examples and applications we could find. A couple are educational, some are of technical interest and some are just LOUD!
Comparison Between Sound Intensity Probes and Acoustic Cameras
Sometimes we are asked about the differences between an acoustic camera and a sound intensity probe and which of the two is better for a particular application. There is no straightforward answer as they are quite different pieces of equipment, used for measuring different things. An acoustic camera is a tool used to locate and analyse sound sources, usually both steadystate and dynamic phenomena. The intensity probe is used to find the sound intensity at a particular position, usually a steadystate phenomena.
What is the difference between microphone types?
We're often asked what is the difference between microphone types; free field, diffuse field and pressure. For a run-of-the-mill ½ inch microphone the short answer is nothing. However the long…
Prosig Power Units Offer New Levels Of Flexibility
The size and shape of the Prosig P8000 data acquisition systems greatly facilitates installation in locations that are small or difficult to access. Now Prosig can offer a new level…
Orders v Time – Comparing Overall Levels
By combining a speed signal with a data signal and using the Short Time FFT algorithm (Hopping FFT), it is possible to extract order data directly as a function of time (Orders from Hopping FFT) rather than as a function of speed (Waterfall). This is very useful when analyzing a complete operational cycle which includes run ups, rundowns and periods at operational speeds.
Sound Steering
The requirement was to develop a ‘standard’ test for assessing vehicle power steering pump noise (and sound quality). Measurements needed to be objective so that the method would be suitable…
Made To Measure
[Updated 4th October 2021]
In this post, we will discuss the different types of transducers that can be used with the Prosig data acquisition systems and loggers. The post looks at the design and function of the different types of sensors and the applications they are normally associated with.
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Measuring Exhaust Noise Using A P8000 System
The following note describes measuring exhaust noise using a Prosig P8000/DATS system for the refinement of an automotive muffler design for a major after-market exhaust manufacturer in Europe. The particular vehicle under test was required by local legislation to have an overall radiated noise level of less than 70 dB. When tested, the vehicle was found to be producing 71.8 dB of radiated noise. The design of the exhaust system clearly needed to be reviewed and modified. (more…)
Standard Octave Bands
The “standard” centre frequencies for 1/3 octave bands are based upon the Preferred Numbers. These date from the 19th century when Col. Charles Renard (1849–1905) was given the job of improving captive balloons used by the military to observe enemy positions. This work resulted in what are now known as Renard numbers. Preferred Numbers were standardised in 1965 in British Standard BS2045:1965 Preferred Numbers and in ISO and ANSI versions in 1973. Preferred numbers are not specific to third octave bands. They have been used in wide range of applications including capacitors & resistors, construction industry and retail packaging.
A Simple Automotive Noise Test
In a recent article we described how the Prosig P8000 hardware and DATS software had been used to help Dalmeny Racing diagnose a problem with an exhaust bracket on their Formula Ford racing car. Whilst the car was instrumented for structural tests on the exhaust the opportunity was taken to carry out a simple automotive noise test. It was felt that these would provide some useful “real world” data as well as maybe providing some extra information regarding the exhaust bracket failure. After analysing and animating the hammer data it became clear that the engine runup data wouldn’t be needed. However, it was decided that some analysis should be carried out to see if the noise and vibration data backed up the conclusions of the other tests.
Audio Equalisation Filter & Parametric Filtering
When working with audio signals a common requirement is to be able to equalise, cut or boost various frequency bands. A large number of hardware devices on the market provide this capability. The key aspect is that such filters are able to control bandwidth, centre frequency and gain separately. There are broadly two classes of filter used, a “shelving” filter and an “equalising “filter (also known as a “peak” filter). A shelving filter is akin to low pass and high pass filters. An equalising filter is like a bandpass or band reject filter.
