100 Things #94: Road Noise and Active Road Noise Cancellation Measurements

Road Noise and Active Road Noise Cancellation Measurements are easy with SoundCheck. Everyone’s familiar with measuring headphone active noise cancellation with SoundCheck, but did you know it’s also great for in-car measurements of road noise and evaluation of road noise cancellation systems? Simply connect the USB-powered AudioConnect 2 to your microphones and laptop, and start making measurements. Watch this short video to see how easy it is with this compact and cost-effective package.

Make Road Noise and Active Road Noise Cancellation Measurements

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Read more about in-car road noise measurements.

Learn more about automotive testing using SoundCheck.

 

Video Script: Road Noise and Active Road Noise Cancellation Measurements

Everyone’s familiar with measuring headphone active noise cancellation with SoundCheck, but did you know it’s also great for measuring active road noise cancellation and road noise reduction in cars?

In this application, you want to measure the road noise at the location of the driver or passenger ears. A simple and cost-effective way to do this is to position two microphones near the outside of your ears or use a Head and Torso simulator. Here, we attached two SCM microphones to a Listen hat using some clips – we call this a low-budget HATS. This has the added advantage that if you are out on real roads, you can measure in the driver’s position.

Our configuration is simple. The microphones are connected to an AudioConnect 2 audio interface for microphone power and signal conditioning. This is a great application for this interface, as it’s USB powered, so you don’t need a power outlet in your car – you can just run it off your laptop. The AudioConnect 2 is connected via a single USB cable to the computer that is running SoundCheck for analysis.

As you can see, it’s a compact setup that easily fits on your dashboard or passenger seat.

To measure road noise, we simply need to drive at a fixed speed, remain silent – that means no talking, coughing, or children in the back seat –  and record for a fixed period of time. You can then look at both the sound pressure level and the frequency spectra of the road noise.

To evaluate a road noise reduction system, simply repeat the measurement with the noise cancellation turned on and subtract one result from the other to provide a value for the noise-reduction system of the car.

This is just one of many automotive audio measurements you can make with SoundCheck. Others include end of line QC, evaluation of components, tuning, Max SPL, impulsive distortion, Buzz, Squeak and rattle, POLQA analysis of communications systems and more. Check out the automotive section of our website for more information.

 

 

100 Things #75: Test Automotive Audio via A2B Interfaces

SoundCheck features full integration with A2B interfaces, allowing seamless audio measurements with all of SoundCheck’s features and functionality. A2B interfaces connect to SoundCheck using an ASIO stream, which appears in the hardware table just like any other audio device. A2B devices are great for automotive infotainment systems as they are lightweight and easily configured, replacing traditional heavy copper wiring. A custom VI in SoundCheck even allows for A2B interface configuration during a sequence.

Test Automotive Audio via A2B Interfaces

Learn more about using testing automotive audio with SoundCheck

Learn more about connecting to automotive infotainment systems, and using SoundCheck for testing automotive audio, infotainment systems, active road noise cancellation, and more.

Video Script:

Did you know that SoundCheck can be used to test audio devices using the A2B interface? A2B is a high bandwidth, bidirectional, digital audio bus. It transports data, and controls information, clock and power, using a single, 2-wire unshielded twisted pair cable. A2B was developed for automotive applications, replacing heavy copper wire in vehicles with an easy to configure, lightweight system. But it has expanded to be used in other applications, such as distributed audio. For example A2B could be used to wire speakers and microphones used in an office conference room.

SoundCheck can access the audio streams of A2B audio interfaces, such as those from Mentor or Analog devices. Once the A2B configuration is set using the third party setup, ASIO streams can be selected in SoundCheck’s hardware table and used to test an audio components such as hands-free microphones. I’m using the Analog Devices A2B Soundcard connected to nodes with 4 PDM microphones. I can configure my current setup using Sigma Studio. Once that is done, I select “Link Compile Download” in Sigma Studio. This sends the project configuration I made to all my connected devices.

Now in SoundCheck, I’m able to go to Setup > Hardware, and choose the Analog Devices A2B SoundCard ASIO stream as my audio interface. Now that this is setup, I can get data in and out of the A2B interface just like any other audio interface. This means I can use SoundCheck to test all components of an infotainment system or A2B based distributed audio system, ranging from speakers and microphones to more complex communications and voice recognition tests.

100 Things #42: Measuring Max SPL of a Vehicle Infotainment System

SoundCheck is ideal for making in-car measurements such as Max SPL, frequency response and distortion. In fact, SoundCheck is the only full-featured audio test system that offers true nth octave real-time multichannel analysis of 6 microphones simultaneously, that we need for some in-car measurements.  In this short video we demonstrate how we can make Max SPL measurements using a 6 microphone array with SoundCheck and an AmpConnect 621 audio interface. You could make these measurements as part of an end-of-line QC test, in the R&D lab, or to compare various car infotainment systems.

In-Car Max SPL Measurement

Learn More About Automotive Measurements

Watch our Automotive Measurement Seminar in which we make in-car measurements of Max SPL, Frequency response and Buzz, Squeak & Rattle.

Read a short article about the work that the AES Technical Committee on Automotive Audio is doing on Max SPL measurements.

A free pre-written SoundCheck test sequence is available to measure both the Max SPL Spectrum and a single, power averaged value for Max SPL in line with the AES TC-AA working group’s proposed guidelines.

A comprehensive resource on in-car Max SPL measurements is the Audio Engineering Society Technical Committee on Automotive Audio (TC-AA). Their in-vehicle measurements white paper (draft) aims to define repeatable and defined car audio system measurements and in addition to the measurement methods, contains information on standardized test configuration, for example microphone and seat positioning.

Main webpage on SoundCheck for Automotive Measurements.

 

Video Script: Measuring Max SPL of a Vehicle Infotainment System

Did you know SoundCheck can make in-car measurements such as Max SPL, frequency response and distortion? In fact, SoundCheck is the only full-featured audio test system that offers true nth octave real-time multichannel analysis of 6 microphones simultaneously, that we need for some in-car measurements.  In this short video I’m going to demonstrate how we can make Max SPL measurements using a 6 microphone array with SoundCheck and an AmpConnect 621 audio interface. You could make these measurements as part of an end-of-line QC test, in the R&D lab, or to compare various car infotainment systems.

In this test, we use a 6 microphone array to represent the driver’s head. We mount it on a tripod so that it’s easily adjusted to the position where the head would be.

This is placed in the driver’s seat of the car, with the tripod legs as far back on the seat as they’ll go, right against the backrest. The height and angle of the seat are set to the minimum or lowest position. The AES is working on a proposed standard for this type of measurement that defines some very specific dimensions between the pedal and backrest, the height of the stand, and the inclination of the back rest. For this demo, I’m not going to be that precise, but as you can see, I am making sure that I have recorded the dimensions I am using, and the mic array is in a fairly typical driver head position.

Now let’s measure Max SPL. We’ll use broadband monophonic pink noise and we’re going to crank the volume to the max   – even outside of the car this is going to be loud!

It’s hitting 110 dB and we’re going to play it for 30 seconds and take the linear average or Leq. Here you can see the readings on the six microphones, and the black line representing the spatial power average. The test sequence is calculating the overall Max SPL as 111 dB C weighted, and also displays the Max SPL spectrum from 20Hz to 20 kHz.

If you’d like to learn more about in-car measurements, check out our automotive measurement seminar, in which we also demonstrate frequency response and distortion measurements. You can find this in the audio measurements playlist on our Youtube channel! This test sequence that I just used for measuring Max SPL is also available for download, free of charge, from our website.

 

Automotive Audio Measurements (Seminar): Frequency Response, Max SPL, Buzz, Squeak & Rattle

In this practical online seminar, Steve Temme demonstrates in-car measurement of frequency response, Max SPL, and Buzz, Squeak and Rattle using a Bluetooth connection. He discusses considerations such as physical setup, infotainment system controls and the measurement parameters. We then discuss connectivity for automotive testing, explaining and demonstrating the various connectivity options including USB drive, Bluetooth and A2B bus. Finally, we take a look at some of the other audio measurements that you can make using SoundCheck, for example active noise cancellation and voice assistance readiness.

Automotive Audio testing demonstrations include:

  • Frequency Response
  • Max SPL and Max SPL Spectrum
  • Buzz, Squeak & Rattle
  • Connectivity Options – USB, Bluetooth, A2B bus
  • ANC and Voice assistance readiness

Presenters: Steve Temme
Duration: 32 Mins

Automotive Audio Measurement Resources

This seminar was originally broadcast on July 21st 2022. The recording below does not include the live Q&A at the end for attendee confidentiality reasons. However, several links to additional resources were provided during the Q&A session, and these are provided below.

  1. Test sequence for in-car audio measurements. This sequence measures the impulsive distortion, frequency response, and maximum sound pressure level of a vehicle
  2. An article by Steve Temme on automotive Max SPL measurements. Originally published in VoiceCoil magazine, June 2022.

More about how to Measure Automotive Audio

Check out our main page on Automotive Audio Testing, which includes links to test sequences, relevant products and more.

Learn more about Connecting to Automotive Infotainment Systems

Maximum SPL measurements in cars

Buzz, Squeak and Rattle measurements

AES Technical Committee on Automotive Audio. Listen, Inc. works closely with this group to ensure that our measurement capabilities align with the measurements recommended by the AES.