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2020, November

What defines a Sound Level Meter in the US has changed.
ANSI/ASA S1.4 equals IEC 61672. Understanding the differences.

What had been previously described as “The Atlantic Divide” in sound level meters (SLM) is gone. With the adoption of ANSI/ASA S1.4 (all three parts) from IEC 61672 (all three parts) in July 2014, the harmonization of the ANSI and ISO standard for Sound Level Meters is complete. Users of SLMs do not need to be expert in the details. However, a good understanding of the new regulation is needed if measurement results are ever challenged. We will review the new regulation from an end-user’s view. We will describe what documentation verifies that a Class 1 sound level meter fulfills ANSI/ASA S1.4. Each part of ANSI/ASA S1.4/IEC 61672 has its intended audience from the SLM designer/manufacturer, accreditation body, to the calibration laboratory.

Author: MacMillan, Brian; Nigsch, Berno

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2018, October

Challenges and Best Practices for Microphone End-of-Line Testing

Due to the increasing use of microphones in many applications such as automotive or artificial intelligence, the demand for fast and reliable microphone test processes is growing. This paper covers various aspects of the design of an end-of-line microphone test system. A prevailing challenge is to properly control the sound source, as loudspeakers have a tendency to vary their performance due to many influences. The acoustic environment for the test must provide reproducible conditions and is ideally anechoic. Noise from outside must be damped across the measurement bandwidth, so that it doesn’t affect the results. Different testing requirements for various types of microphones are shown. Different methods for defining limit criteria are discussed.

Author: Schmidle, Gregor; Beach, Mark; MacMillan, Brian
AES Paper Number 10096

2017, October

Objective Testing of High-End Audio Systems

The high-end audio equipment market is filled with extraordinary products. Although the engineering and the materials utilized are often of the finest available, the quality control of such systems is frequently done subjectively rather than objectively. This paper shows some best practice examples of how to deploy effective quality measurement systems through the complete life cycle (R&D, QC installation, and repair) of high-end audio systems.

Author: Schmidle, Gregor; Köck, Gerd; MacMillan, Brian
AES Paper Number 9835

2017, June

EOL Testing of Acoustic Devices

A Truly Multidisciplinary Task

This article describes the challenges of keeping up yield and quality in a high-volume acoustic device production environment. It highlights several aspects such as limit definition, test jig design, data handling, system replication, system maintenance and many more.

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Author: Schmidle, Gregor
2017 Loudspeaker Industry Sourcebook, page 32-36

2014, October

Retrofitting a complex, safety-critical PA system for periodic testing

The paper describes considerations and the implementation of retrofitting a fully-automated procedure, for testing a public address system, into a safety-critical environment (a nuclear power plant). There are over 4000 loudspeakers, about 200 amplifiers as well as various alarm-signal generators that need to be tested every day within a few minutes. Additionally, all command room microphones are checked using a semi-automated procedure. The procedures were designed and configured to not only reliably detect single defective components, but also to not produce any false alarms.

Authors: Schmidle, Gregor; Schwizer, Philipp; Häns, Winfried
AES Paper Number 9117

2013, October

End-of-line Test concepts to achieve and maintain yield and quality in high volume loudspeaker production

Managing high volume, multiple line and location loudspeaker production is a challenging task that requires interdisciplinary skills. This paper offers concepts for designing and maintaining end-of-line test systems that help to achieve and maintain consistent yield and quality. Topics covered include acoustic and electrical test parameter selection, mechanical test jig design, limit finding strategies, fault-tolerant workflow creation, test system calibration and environmental influence handling as well as utilizing statistics and statistic process control.

Author: Schmidle, Gregor
AES Paper Number 8990

2012, October

Overview and Comparison of and Guide to Audio Measurement Methods

Modern audio analyzers offer a large number of measurement functions using various measurement methods. This paper categorizes measurement methods from several perspectives. The underlying signal processing concepts, as well as strengths and weaknesses of the most popular methods are listed and assessed for various aspects. The reader is offered guidance for choosing the optimal measurement method based on the specific requirements and application.

Authors: Schmidle, Gregor; Zanatta, Danilo
AES Paper Number 8705

2011, October

A Systematic Approach to Measurement Limit Definitions in Loudspeaker Production

A typical end-of-line loudspeaker test comprises ten or more different parameters tested. Each parameter has its own pass/fail limits contributing to the overall test result of the loudspeaker and therefore to the yield of the production line. This paper gives a comprehensive overview about commonly used limit calculation methods and procedures in the industry. It also delivers systematic guidance for choosing the right limit scheme for maximizing yield, quality and throughput.

Author: Schmidle, Gregor
AES Paper Number 8472

2010, November

A Reliable Procedure for Polarity Measurements on Line Arrays

The performance of a line array strongly depends on the correct installation of its loudspeakers. For instance, a single speaker with incorrect polarity may clearly compromise the sound level and directivity of the whole system. The identification of such errors however can be very time consuming. Therefore, it is desirable to have a fast, yet reliable procedure to finding such array elements. This paper presents a step-by-step method to check the integrity of a line array, and to find the cause in case of a polarity problem. Besides the theoretical background, a successful practical case is described.

Authors: Becker, Markus; Schmidle, Gregor
AES Paper Number 8156

2009, October

Design Optimizations for a High Performance Handheld Audio Analyzer

All types of advanced mobile devices share certain design challenges. For example, they must incorporate a powerful-enough embedded processor system to support a full featured easy-to-use human interface at low power consumption. But designing a multi-function handheld audio analyzer then adds even more unique challenges based upon further professional requirements. These include extremely low measurement noise floor, safely and precisely handle wide voltage measurement range (absolute and dynamic), compatibility with measurement microphones and other input sources, adherence to a wide variety of necessary international and industry standards for measurement. Additional requirements include the efficient display of complex data onto a restricted size display, and efficient and safe operation in many different locations and physical environments. These place further design burdens on the user interface and the instrument package, respectively.

Author: Becker, Markus
AES Paper Number 7908