Tag Archive for: room acoustics.

100 Things #55: Make RT60 Room Acoustics Measurements With SoundCheck

SoundCheck makes fast, reliable RT60 room acoustics measurements with fully calibrated signal paths, ensuring accurate results. This helps product designers quantify how their devices will interact with the acoustics of a particular type of room, and simulate real-world conditions to test their devices.

Making RT60 Room Acoustics Measurements with SoundCheck

Learn more about making RT60 Room Acoustic Measurements

The Room Acoustics Measurement video demonstrates Room Acoustics Measurements in the First Korean Church in Cambridge, MA.

 

Video Script: RT60 Room Acoustics Measurements

Did you know that SoundCheck can make RT60 Room acoustics measurements? This helps product designers quantify how their devices will interact with the acoustics of a particular type of room, and simulate real-world conditions to test their devices.

This is particularly important for products such as smart devices and communications devices where the user may place them in a variety of locations. Test environments to simulate these must be carefully designed and fully characterized, with known reverberation time – that’s the signal decay time,  and clarity – the ratio of early reverberation to later reverberations.

The difference between SoundCheck and the more basic room acoustics packages out there is that SoundCheck makes all the measurements with advanced filtering algorithms and fully calibrated signal paths. This is important because acoustic measurements are sensitive to background noise and simulated real-world measurements are typically performed in noisy rooms or environments, for example, a kitchen or train station. Calibrated measurements allow us to measure the noise floor and set the speaker level accordingly for accurate RT60 measurements. Plus, if you’re serious about smart device measurements you probably already have SoundCheck, so it makes sense to keep everything in the same test environment.

Let’s take a look. Here we have a Bruel & Kjaer omnidirectional sound source. These speakers are all connected in parallel to radiate sound evenly and in-phase in all directions. We’re going to capture the sound with 4 of our own SCM microphones, connected to the AmpConnect 621 audio interface which has 6 input and 2 output channels. The test sequence (which is available free of charge on our website) plays a continuous sine sweep out of the omnidirectional sound source and the room response is recorded with the four microphones. This test signal has excellent noise immunity and it’s easy to separate the fundamental from the harmonics to minimize distortion effects on the measurements. Room acoustics values are then determined using a backwards integrated impulse response method. This method is very fast and requires just one measurement at each location. The results from the four microphones are averaged and displayed as single lines on the graph for T20, T30 and T60 measurements, as well as all 3 clarity curves.

If you’d like to learn more about this optional module, or download the test sequence, visit our website, www.listeninc.com.

 

 

 

RT60 Room Acoustics

The RT60 room acoustics sequence measures reverberation time and clarity of a room using multiple microphones to accurately characterize measurement environments. This is important for smart device testing as measurements of both speech recognition and audio output often need to be made in fully characterized rooms with known reverberation times and clarity. The method used in this sequence is fast, accurate, and made using fully calibrated signal paths. This sequence uses an omnidirectional speaker to play a Log Sweep from 250Hz – 15kHz and four microphones measure the impulse responses generated. These waveforms are analyzed using the Time Selective Response and room acoustics algorithms to calculate reverberation time (T20, T39, T60) and clarity (C7, C50 and C80) according to ISO 3382-1:2009.
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SoundCheck® 19 Released: New Features for Multichannel Measurements

SoundCheck® 19,  the new release of Listen, Inc.’s flagship audio test and measurement system, offers additional functionality for multichannel measurements, including a new Multi-channel RTA, WASAPI-exclusive mode, and AmpConnect 621 control. Additionally, the inclusion of room acoustics measurements offers increased capability for those looking to evaluate devices in real-world situations. Many of these features also add value on the production line, minimizing setup time, reducing the chance of user-error, and ensuring smoother operation in automated situations.

In this release, the original ANSI S1.11-2004 Class 0 standard compliant, single-channel RTA has been enhanced to show multiple channels simultaneously.  Settings for these can be configured independently, e.g. adding different weighting curves, and the power-averaged response displayed. This presents a convenient view of many measurements across a wide range of applications including overlaying left and right earphone responses to check for fit and seal, microphone array captures (e.g. in-vehicle cabin measurements), real time adjustment of active noise cancellation filter, and more.  For maximum flexibility, spectrum settings are set independently for each channel, and all multi-channel RTA functionality can also be used within a test sequence for automation.

The optional RT60 Room Acoustics module enables measurement of the reverberation time and clarity of any room or space with fully calibrated signal paths. This is useful for quantifying how speakers will interact with the acoustics of a particular type of room. It can also help identify problems with room acoustics so that the floor, ceiling and walls can be treated accordingly. SoundCheck uses a continuous sine sweep with the Log TSR algorithm to obtain the impulse response. The reverberation decay curve is calculated from the backwards integrated impulse response. This method, conforming to ISO 3382-1:2009, offers extremely fast measurements, requires just one measurement at each location, and minimizes the effect of noise and distortion on the measurement.

Another enhancement is the option to use WASAPI-exclusive mode with Windows 10 audio devices. This advanced interface offers superior communication with audio devices, allowing SoundCheck to bypass the Windows audio engine, and send audio streams directly to the device. This delivers lower latency and ensures that sample rate conversion from the built-in Windows audio engine will not occur. It also enables SoundCheck to put an exclusive lock on the audio interface so that a measurement cannot be disrupted by system sounds. The ability to use multiple WASAPI devices simultaneously offers significant advantages for multichannel applications, particularly where the channel count requires multiple audio interfaces. WASAPI and ASIO devices can be combined to increase channel availability.

SoundCheck 19 supports AmpConnect 621, Listen’s new high resolution (up to 192kHz) multichannel audio interface. AmpConnect 621 has no front panel controls; it is exclusively configured via the SoundCheck 19 software. Set-up and configuration is extremely simple and fast with full plug-and-play functionality and TEDS support for automatic identification, configuration and calibration of microphones and accelerometers. The absence of front panel knobs also provides an added level of test integrity by ensuring that settings cannot be inadvertently adjusted outside of your test configuration. SoundCheck 19 with AmpConnect 621 is a simple and cost-effective solution for automotive measurements with a 6-microphone array, sound power measurements, or for measuring devices with multiple speakers such as smartphones or sound bars.

Also new is a diagnostic window which enables suppression of warning dialog windows when running a sequence, logging any errors, warnings, and information in a separate file. This is useful when Soundcheck is run in unattended or in highly automated situations (for example, on a production line) where dialog windows would interrupt the execution of a sequence. It also facilitates troubleshooting as the log is easily shared via email. SoundCheck also now allows the Drok USB Controller Knob to be used to adjust the SoundCheck Signal Generator, simulating the feel and control of operation of a traditional manual analog signal generator. Used with other virtual instruments such as the RTA, spectrum analyzer and distortion meter, this offers a rapid way to identify defects by observing the response while manually fine-tuning the signal generator.

 

More information (video, PDF, graphics, etc.): https://www.listeninc.com/products/soundcheck-overview/new-soundcheck-release-version-19/