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Automotive Max. SPL Measurements

In this short article, Steve Temme introduces the efforts of the Audio Engineering Society (AES) technical committee working on automotive audio to standardize the way essential attributes of complex automotive
audio systems are measured across the industry. He explains why Max SPL measurements are important, defines this measurement, and describes the standardized measurement procedure suggested by the committee. Test configuration and physical setup is discussed, and example results presented.

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Enhanced Perceptual Rub & Buzz Measurement for Testing Automotive Loudspeakers

Loudspeaker Rub & Buzz faults are a problem for automotive manufacturers as they sound harsh and immediately give the perception of poor quality. There are two places such faults can occur – during speaker manufacturing and installation of the speaker in the car. A buzzing loudspeaker in a car is disappointing to a customer and is costly to replace. It is also challenging for a service center to determine exactly where the buzzing is coming from and whether it is caused by a faulty loudspeaker or bad installation. Perceptual distortion measurements are often considered the holy grail of end-of-line testing because rejecting speakers with only audible faults increases yield. Although such measurements have been around since 2011, production line adoption has been slow because until now, sensitivity to background noise has made limit-setting challenging. In this paper, a new algorithm is introduced that uses advanced technology to reduce the impact of background noise on the measurement and offer more repeatable results. This facilitates limit setting on the production line and makes it a truly viable production line metric for increasing yield. This same metric may also be used for end-of-line automotive quality control tests. Results from various algorithms will be shown, and their correlation to subjective and other non-perceptual distortion metrics explained.

Authors: Steve Temme, Listen, Inc.
Presented at 2022 AES Automotive Conference, Dearborn, MI

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Automotive Audio Testing Seminar

July 21st, 2022. 9.00am and 2.00pm Eastern US time (6.00am and 11.00am West Coast time)
July 27th, 10.00am China time

In this practical online seminar, Steve Temme will demonstrate in-car measurement of frequency response, Max SPL, and Buzz, Squeak and Rattle using a Bluetooth connection. He will discuss considerations such as physical setup, infotainment system controls and the measurement parameters. Steve and his colleagues will then discuss connectivity for automotive testing, explaining and demonstrating the various connectivity options including USB drive, Bluetooth and A2B bus. Finally, we’ll 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. 

在这个实用的网络研讨会中,Steve Temme 将演示如何使用蓝牙连接进行车内测量,以测量频率响应、最大 SPL 以及异常音。 他将讨论物理设置、信息娱乐系统控制和测量参数等考虑因素。 然后,Steve和他的同事将讨论汽车测试的连接性,解释和演示各种连接选项,包括 USB 驱动器、蓝牙和A2B 总线。 最后,我们将看看其他您可以透过SoundCheck进行的音频测量,例如主动降噪以及voice assistance readiness测量。

AES 2022 International Automotive Audio Conference

We’ll be attending and exhibiting at the AES International Automotive Conference in Detroit, June 8-10. Stop by and visit our booth to learn more about the latest version of SoundCheck, including a host of new features designed for multichannel and communications testing, as well as the new enhanced perceptual Rub & Buzz algorithm. Listen founder and president, Steve Temme, will be presenting a paper on June 8th (paper session 1, 10.30 am) detailing this new algorithm, and will also participate in a panel discussion on Max SPL measurement in cars at 4.00pm on June 9th.

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Automotive Max SPL

The sequence measures the Max Sound Pressure Level (SPL) of a car infotainment system in the vehicle’s interior

The sequence uses a 6 microphone array mounted at either the driver or passenger locations. A 30 second pink noise stimulus having an RMS level of -12 dBFS is played through the infotainment system and captured by SoundCheck’s Multi-channel Real Time Analyzer (RTA). The Multi-channel RTA produces 6 RTA curves which are then power averaged to produce a Max SPL Spectrum. The spectrum is then power summed to produce a single value for Max SPL.

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Audio Testing with SoundCheck at Sound Hub Denmark

February 25th, 2020. 8.30-17.00

Learn how to measure audio quality of both simple and complex modern audio devices, in both R&D and production environments. Get to know the basics of SoundCheck; one of the world’s most popular audio test software systems, and learn about how to build a test sequence incl. recommendations for the equipment used. Additionally, you will get familiar with specific methods and conditions applied for voice-activated audio testing for e.g. automotive among others.

Join us for an inspiring day, where the Founder and President of Listen, Inc., Steve Temme from US together with Danish representatives and people from GRAS share knowledge about do’s and don’ts.

Sound Hub Denmark has the software and recommended equipment in house to further assist you after this course.

Program Outline

8.30–9.00: Sign-in & welcome

9.00-12.00: Audio Measurement Basics: What to measure and why

  • Learn about different test configurations and the products you need for a test system (software, microphones, interfaces, chambers etc.)
  • Understand the basics of SoundCheck – one of the  world’s most popular audio test systems used on over 10,000 production lines worldwide
  • Learn how to build a simple test sequence for speakers and microphones in SoundCheck, and how to adapt this for different products
  • Common challenges and pitfalls with audio testing
  • Transitioning test from the R&D lab to the production line

12.30: Light lunch

13.15-16.00: Voice-Activated Device Testing, Automotive, smart speakers, hearables

  • Automotive infotainment systems, hearables, smart speakers and many other audio devices are now voice-activated. Such devices are complex to test as they have numerous wired and wireless connections and often contain signal processing, both on the record and the playback side. This means that their characteristics change according to ‘real world’ conditions of the environment that they are used in, such as automotive cabin and roaad noise, background noise, playback levels, and room acoustics. Furthermore, many aspects of the device may need to be tested, ranging from voice recognition to music playback, operation as a hands-free telephone, and even hearing assistance. Often measurements need to be made at different levels and different environmental conditions. In this session, we will discuss the test configurations, tools and techniques that enable accurate measurement of the audio performance of such devices under the many various real-world conditions in which they are used.

16.00-17.00: Hands on and drinks

Space is limited so please sign up on the event page on the Sound Hub Website.

Testing Voice-Controlled & Smartphone Integrated Infotainment Systems

A tutorial and accompanying paper that was presented at the AES Automotive Conference, Sept 11-13, 2019, Neuburg an der Donau, Germany.

Voice-controlled and smartphone integrated vehicle infotainment systems are notoriously complex to test. They have numerous connections from wired to wireless and contain much signal processing, both on the record and on the playback side. This means that their characteristics change according to ‘real world’ conditions of the vehicle’s environment, including cabin acoustics and background noises from road, wind and motors. Furthermore, their multifunctional nature means that there are many aspects of the device that may need to be tested, ranging from voice recognition to music playback and operation as a hands-free telephone. Due to their complex non-linear use cases, these devices often need to be tested at different levels and different environmental conditions.

This tutorial offers practical hands-on advice on how to test such devices, including test configurations, what to measure, the challenges of making open-loop measurements, and how to select a test system.

Download presentation (slides)

Download accompanying paper

AES International Conference on Automotive Audio – Munich – September 11-13, 2019

Listen is a gold sponsor and exhibitor at the AES International Conference on Automotive Audio in Munich, Germany on September 11-13.

Listen founder and president, Steve Temme, will be presenting a tutorial on ‘Testing Voice-Controlled and Smartphone Integrated Infotainment Systems’ at 2pm on Sept 11th. In this tutorial he will discuss the challenges of implementing audio tests in cars when the signal path is often via a smartphone and/or the car’s own voice-controlled system, and demonstrate how modern test systems can use techniques such as frequency shift and resampling to enable accurate measurement of car audio characteristics ranging from simple frequency and distortion measurements to voice control and communications in the presence of background noise.

On display at the the booth will be various options for testing automotive audio including the SoundCheck test system, Listen’s own audio test hardware, and 3rd party hardware such as 6 microphone arrays and head and torso simulators. On the booth, Listen will also be demonstrating how SoundCheck fully integrates with, and controls, the Mentor A2B interface to enabled rapid automated testing of systems and components that use the A2B bus.

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SoundCheck/Mentor A2B for Automotive Audio

mentor_a2bWe are excited to announce that SoundCheck fully integrates with the Mentor A2B interface for testing automotive audio connected via the Analog Devices A2B digital bus. The Mentor Analyzer, which handles the transmission of signal in to and out of the bus, is viewed as an ASIO interface by SoundCheck, enabling SoundCheck to read/write to the device and therefore analyze any transducer connected to the A2B bus. A custom VI permits control of the Mentor A2B interface configuration via SoundCheck. This means that it can be controlled from within a SoundCheck sequence, for example loading configurations and starting/stopping ASIO streams. This makes it an ideal R&D or production line test solution for automotive audio, or for anyone testing transducers connected via A2B bus.

Watch a video demonstration of an automotive audio test using the Mentor A2B interface:

 

Please see our knowledgebase article for download links and installation instructions.

Contact your Listen sales engineer for more information.

Triggered Record Using WAV File and 6 Mic Array

This sequence allows you to measure a playback system without analog inputs using a 6 microphone array. Specifically, the sequence is designed to measure an in-car audio system. A stimulus WAV file is created in SoundCheck and transferred to the device under test (DUT) where it is played back and the response captured by SoundCheck using a triggered record function. The 6 recordings are batch analyzed to produce individual fundamental curves and the curves are post-processed to produce a single average curve from which an average sensitivity value is calculated.

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