Knowing where a noise originates is the first step in addressing it!
The Simcenter Sound Camera is a sound source localization tool that makes it easy to pinpoint noise sources – just point the Sound Camera at an object, and the purpose-built Sound Camera software shows results in an easy to interpret picture (see Figure 1).
Figure 1. Sound Camera results are overlaid on a picture or video, making them easy to understand.
The Simcenter Sound Camera is a multi-channel microphone array, built on digital MEMS technology. All the signal processing is built into the Sound Camera, so there is no other equipment required: no external microphones to plug in or calibrate, no additional acquisition module to lug around. Plug the Sound Camera into the laptop via a standard Ethernet cable to start solving the noise problem.
This Simcenter Sound Camera article covers:
Sound Camera Features
Included & Optional Equipment
Sound Camera Software Overview
Simcenter Testlab HD Acoustic Camera Software
Simcenter Testlab Array Software
Reference Material
1. Sound Camera Features
Integrated electronics
All the necessary signal processing is performed on-board the Sound Camera, no external “DAQ” front-end is needed. A single Ethernet cable connected to the PC is all that is required. See Figure 2.
Figure 2. Sound Camera features integrated signal conditioning, sending digital data directly to the host computer without the need for a separate front end.
Digital MEMS microphones
Integrated into the rugged aluminum frame of the Sound Camera are 45 digital MEMS 24-bit microphones. (See Figure 3 below) MEMS microphones are etched directly onto a silicon wafer, making them very small, stable and durable. They feature a high signal-to-noise ratio, very low power consumption, and good sensitivity. MEMS microphones are often used in smart phones due to their reliability, stability and robustness.
Figure 3. Sound Camera features digital mics, video camera and automatic range finder built in!
MEMS microphones are etched directly onto a silicon wafer, making them very small, stable and durable. They feature a high signal-to-noise ratio, very low power consumption, and good sensitivity. MEMS microphones are often used in smart phones due to their reliability, stability and robustness.
On board wide angle video camera and distance sensor
The Simcenter Sound Camera also comes with a wide-angle video camera and an infrared distance sensor (see Figure 3). The wide-angle lens provides an extended field of view. This feature allows the Sound Camera to be moved into the acoustic near field, close to the noise emitting object, and still provide a view of the entire object. Source localization is performed live in real-time with the video feed, making the Sound Camera perfect for localizing noise on moving objects, or for hand-held trouble shooting. The built-in distance finder continually updates the distance to the measured object for optimal localization results.
Modular arms for flexible frequency ranges
One of the Sound Camera’s most revolutionary features is its ability to be configured in three different sizes: Center section, Center + Short Arms, Center + Long Arms (see Figure 4). By adding one of the two optional arm extension kits, the diameter of the Sound Camera can grow, greatly increasing the spatial resolution and frequency range of the antenna. As the frequency of sound gets lower, the wavelength (size) of the sound waves grow longer. By increasing the overall diameter of the array, the arm extension kits make the Sound Camera capable of localizing lower frequencies.
Figure 4. The Sound Camera can be configured in 3 different sizes by adding optional arm extensions.
The circular center section of the Sound Camera features 45 microphones, and has a diameter of 28 cm. By adding one of the optional arm extension kits, additional microphones can be added, increasing the spatial resolution and expanding the applicable frequency range. The short arm extensions add 4 microphones to each of the nine arms, totaling 81 microphones, with an overall diameter of 60 centimeters. The long extensions contain 8 microphones each, bringing the total number of microphones to 117, and an array diameter of 150 cm.
Input for additional transducers
Standard Sound Camera hardware also includes an input for up to four additional transducer signals to be measured simultaneously with the microphones built into the Sound Camera. By pairing the Sound Camera with Simcenter Testlab HD Acoustic Camera software, these signals can be used to provide coherent phase references for additional processing.
Multi-frame operation capable
Simcenter Sound Camera also comes equipment-ready to be combined with other Simcenter SCADAS data acquisition systems (see Figure 5).
Figure 5. Simcenter SCADAS and Sound Camera can be combined to add sound source localization capability to any high-channel count measurement.
By combining the SCADAS and Sound Camera, the Sound Camera’s sound source localization capability can be combined with standard data acquisition campaigns including measurements with tachometers, CANbus channels, GPS data, and more. All data is time-aligned and recorded simultaneously in Simcenter Testlab software.
The Sound Camera comes packaged as a complete kit, with everything you need in a rugged, weatherproof carrying case (Figure 6).
Figure 6. Included equipment for the Sound Camera. Optional short arm extensions shown.
Circular center section (45 microphones) with integrated electronics, wide-angle video camera & infrared distance sensor. Includes wind screen.
PoE (Power-over-Ethernet) adapter w/ power cord
5m network cable to connect array to PoE adapter
1m network cable to connect PoE adapter to PC
AUX-IN breakout cable with 4 female BNC connectors
Multi-pin connector for optional external battery & IRIG-B (multi-frame operation)
Manfrotto tripod
Pistol-grip handle for hand-held operation
Rugged Pelican case with customized foam
Sound Camera software (not pictured)
Optional equipment includes:
Arm extensions
Optional short arm extension kit (total 81 microphones)
Optional long arm extension kit (total 117 microphones)
Simcenter Testlab HD Acoustic Camera software – enables advanced post-processing functionalities that can be applied to recordings made with Sound Camera. Additional capabilities include
Coherent processing using external sensors.
Enable multi-frame mode with Simcenter SCADAS hardware for high channel count tests.
iNAH – nearfield acoustic holography algorithm. Improves low-frequency localization results and allows sound power quantification/ranking of sources.
Order Extension – localization vs RPM, .
Deconvolution – Allows increasing the spatial resolution of farfield beamforming measurements.
The Sound Camera software is designed to produce sound source localization results quickly and easily. The main screen area of the software is broken up into four main sections, as shown in Figure 7 below. These sections are:
live frequency spectrum with selection cursors
live overall level and band contribution level
live hologram localization results
reference snapshot, making for easy A/B comparisons on the fly
Figure 7. Sound Camera software is designed to be easy to use, providing real-time results with no need for extra processing.
The user selects a band of interest in the live frequency spectrum using the double cursors, and the hologram display updates automatically (Figure 8), highlighting the noise source for the selected frequency band. The level contribution display in the upper right gives an indication of how much the selected frequencies contribute to the overall noise level. The reference snapshot display can be used for quick A/B comparisons: for instance, when testing different product variants, or evaluating sound treatment packages.
Figure 8. Selecting different frequency bands show distinct sources of noise. Notice the engine cover seems to be doing its job – the noise only appears to come from the edges!
Making a recording of the data is also possible and allows for further investigation and replay. The user has the option to continuously loop the playback over a specific range of time (useful for transient events) or can choose to average the sound data over the entire selected range for stationary noises.
Localization results can be saved and exported as a still picture, or a movie file.
In addition to acquiring and analyzing in the Simcenter Sound Camera software, the data can also be analyzed in Simcenter Testlab.
To use the HD Acoustic Camera workbook, select it from the main Simcenter Testlab menu under “Tools -> Add-ins". With Simcenter Testlab revision 2206.0002 and higher, the HD Acoustic Camera workbook uses 114 tokens. In earlier revisions of Simcenter Testlab, HD Acoustic Camera was not available via tokens.
Figure 9: Acoustic array add-ins available in Simcenter Testlab.
Array data analysis includes several different algorithms for analyzing data as well as creating an array definition and spacing. Array batch processing and reporting enables reports to be created quickly.
6. Reference Material (download links to zip file)
