End-Of-Line Headphone Testing

With 3M - Science Applied to Life

The Problem

3M needed a modular solution which allowed operators to test different kinds of headphones easily in a soundproof environment. All while conforming to high 3M standards and industry regulations for CE marking. Test consistency, accuracy and operator safety were important to the customer.

The Solution

Using the QATS platform and experience from other projects, we constructed a soundproof testing chamber. We controlled the system using an Allen-Bradley PLC and a Windows PC.

Both Soundproof Test Stations

Test Maintenance

Both Soundproof Test Stations

1/2

Using the QESTIT QATS platform and experience from other production testing projects, we constructed a soundproof testing chamber. This chamber used pneumatic doors with a 'slide out' platform that had a fixture where headphones would be placed. The platform would retract into the chamber and the doors would close, blocking all sound from the production environment. The chamber stimulates the headphones with pink noise. This was used to test the assembly of the headphones and make sure surround microphones and headset passive attenuation function within test limits. Internal headphone speakers were also tested using high quality measurement microphones.

A unique aspect of this system was the self calibration feature used when playing pink noise into the chamber. The audio signal was automatically calibrated with a reference microphone mounted inside of the test chamber. Using a characterization the acoustical profile and calculated compensation to create a perfectly flat acoustical spectrum. This significantly increases accuracy and reduced chamber calibration costs.

Due to the force that the doors used when closing, additional safety features were used to prevent users from being injured. One such feature was light curtains, that detected if users inserted their hands into the chamber when the doors were closing. Other decision was using a Safety Allen-Bradley PLC Relay to handle the safety aspects of the test fixture. If the Windows PC was the brain of the system, the PLC was the central nervous system, reacting quickly in the case of danger. in order to fulfill the CE-marking requirements.

"We're extremely pleased with the quality of this system. Its self-calibrating and safety features have been extensively tested."

Mattias Ericsson, Team Lead, QESTIT Systems

When delivering systems to our customers, we provide a document pack which contains an operator manual, test specification and hardware manuals. We also CE mark our systems (alongside the needed documentation). Operator safety is the most important concern when working with high voltage electronics or moving components. With our systems, you can sit conformable knowing they are well-tested before launch.