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Practical Measurement of Bluetooth and Lightning Headphones

Author: Daniel Knighten.  Reprinted from the July 2017 issue of Voice Coil.

In this article, Dan Knighten discusses how to overcome the challenges of measuring headphones with wireless and digital interfaces such as Bluetooth, Lightning and USB-C to make the same measurements as on conventional wired headphones.

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Headphone & Headset Measurements – Tokyo, Japan – March 9, 2018

Presented by:

listen_gras_logos2

headphones

 

 

 

Due to popular demand, we are now holding our headphone testing seminar in Tokyo!

Learn about the latest in headphone test systems and methods from design to EOL Test. Industry experts Steve Temme (Listen, Inc.) and Peter Wulf-Andersen (G.R.A.S.), as well as guest speaker Dr. Sean Olive (Harman International) will discuss test equipment (ear couplers, test fixtures, test software and hardware) and demonstrate practical test setups for both R&D and QC headphone testing. It will cover in-ear monitors, Bluetooth, lightning/USB, noise-cancelling and high resolution headphones, in addition to conventional analog headphones. You can even measure your own headphone using our equipment in the hands-on session. Please see the full agenda below.

There is no charge for this one-day seminar. Lunch will be provided. Space is limited, so please RSVP today.

Location and Dates:

Tokyo: Friday March 9th, 2018. Otemachi SUNSKY ROOM 27th floor, room #B  Asahi Seimei Otemachi Bldg. 2-6-1 Otemachi, Chiyoda-Ku, Tokyo.

 

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See what people are saying about this event (we presented similar last year in the US)

Agenda (10am-4pm)

  • Introduction
  • Overview of Headphone Test Systems and tools
    • Traditional tools vs. modern consumer demands
      • Introduction to head and ear related terminology and definitions.
      • Historical perspective and background for the tools and standards used today.
      • Limitations vs. Possibilities in term of the measurement capabilities. How does that relate to the modern challenges with Bluetooth and ANC related testing tasks?
    • Tools for Next Generation Headphone Testing
      • Solutions to some the challenges addressed above.
      • Examples based on products and measurements.
    • What about frequencies above 20kHz? Science or marketing? Measurement Consistency – Development vs. Production
      • Progress in measurements from Head and Torso Simulator (KEMAR) to Production Test Fixture (45CC – flat plate). How the different components affect the measurements:
    • Software and hardware for headphone testing including typical headphone measurements and test setups
  • Practical examples of headphone measurements on.
    • Analog Headphones
    • Bluetooth Headsets
    • ANC Headphones
    • Lightning/USB Connected Headphones (using triggered recordings)
    • Hi-Res Headphones
    • In-ear monitors
  • Measurements including:
    • Frequency Response relative to a target response
    • Left/Right tracking
    • Impedance
    • Noise attenuation
    • Distortion including Non-Coherent Distortion
    • Standards including Max SPL EN-50332 & IEC-60268-7
  • Headphone Design: Perception and Measurement of Headphones – What is the Preferred Target Response? (Guest Speaker: Dr. Sean Olive, Harman International)
  • Hands-on testing: Bring your own device and test it using one of our measurement setups

Reserve your space

Headphone & Headset Measurements – Seoul, Korea – March 6, 2018

Presented by:

listen_gras_logos2

 

headphones
Due to popular demand, we are now holding our headphone testing seminar in Seoul!

Learn about the latest in headphone test systems and methods from design to EOL Test. Industry experts Steve Temme (Listen, Inc.) and Peter Wulf-Andersen (G.R.A.S.), as well as guest speakers Dr. Sean Olive (Harman International) and Prof. Lee (New Media Communication Joint Institute of Seoul National University) will discuss test equipment (ear couplers, test fixtures, test software and hardware) and demonstrate practical test setups for both R&D and QC headphone testing. It will cover in-ear monitors, Bluetooth, lightning/USB, noise-cancelling and high resolution headphones, in addition to conventional analog headphones. You can even measure your own headphone using our equipment in the hands-on session. Please see the full agenda below.

There is no charge for this one-day seminar. Space is limited, so please RSVP today.

Location and Dates:

Seoul: Tuesday March 6th, 2018. Korea National University, 1 Gwanak-ro, Gwanak-gu, Seoul.

 

Print

 

 

See what people are saying about this event (we presented similar last year in the US)

Agenda (9am-4pm)

  • Introduction
  • Overview of Headphone Test Systems and tools
    • Traditional tools vs. modern consumer demands
      • Introduction to head and ear related terminology and definitions.
      • Historical perspective and background for the tools and standards used today.
      • Limitations vs. Possibilities in term of the measurement capabilities. How does that relate to the modern challenges with Bluetooth and ANC related testing tasks?
    • Tools for Next Generation Headphone Testing
      • Solutions to some the challenges addressed above.
      • Examples based on products and measurements.
    • What about frequencies above 20kHz? Science or marketing? Measurement Consistency – Development vs. Production
      • Progress in measurements from Head and Torso Simulator (KEMAR) to Production Test Fixture (45CC – flat plate). How the different components affect the measurements:
    • Software and hardware for headphone testing including typical headphone measurements and test setups
  • Practical examples of headphone measurements on.
    • Analog Headphones
    • Bluetooth Headsets
    • ANC Headphones
    • Lightning/USB Connected Headphones (using triggered recordings)
    • Hi-Res Headphones
    • In-ear monitors
  • Measurements including:
    • Frequency Response relative to a target response
    • Left/Right tracking
    • Impedance
    • Noise attenuation
    • Distortion including Non-Coherent Distortion
    • Standards including Max SPL EN-50332 & IEC-60268-7
  • Design & sound tuning of earphones  (Guest Speaker Prof. Lee, New Media Communication Joint Institute of Seoul National University)
  • Headphone Design: Perception and Measurement of Headphones – What is the Preferred Target Response? (Guest Speaker: Dr. Sean Olive, Harman International)
  • Hands-on testing: Bring your own device and test it using one of our measurement setups

Reserve your space

Bluetooth Headphone Test

bluetooth headset test resultThis sequence tests the send and receive performance of a stereo Bluetooth headset with a built-in microphone using a mixture of analog and digital channels. The left and right earphones are measured simultaneously with a stepped sweep from 20 kHz to 20 Hz using two Bluetooth profiles: A2DP and HFP. The mic is measured with a stepped sweep from 8 kHz to 100 Hz using the HFP profile.

A short 1 kHz tone is pre-pended to the test stimulus which serves as reference tone for resampling and frequency shift operations. Post-processing resampling and frequency shift precisely synchronizes the stimulus and response waveforms prior to analysis. In this case, the HarmonicTrak algorithm is used for frequency response and THD analysis. A2DP frequency response and THD curves are displayed on the first display, followed by A2DP & HFP curves superimposed on a subsequent display. Lastly, the Bluetooth headset’s microphone is tested with HFP and its frequency response is shown on the final display along with the previously collected data.

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Comparison of Wired and Wireless (Bluetooth) Speaker Response

bluetooth_speaker_responseThis test sequence performs frequency response and distortion measurements of a Bluetooth speaker using both a wireless Bluetooth and wired stimuli, and compares the results. This sequence is configured for use with a Portland Tool & Die BTC-4148 or BQC-4148 Bluetooth interface.

Initially, the sequence prompts the operator to turn on the Bluetooth device under test and set it to pairing mode. BTC message steps will connect the Bluetooth device (operator selects the device from a list of detected Bluetooth devices) and connects Bluetooth audio. A 1 kHz test tone is transmitted, and if detected, the test sequence proceeds. A stepped sine sweep from 20 kHz to 100 Hz is played wirelessly to the Bluetooth speaker and measured via a calibrated reference mic.

Two post-processing steps convert the sampling rate and alignment of the response, then an analysis step calculates the frequency response and THD. The Bluetooth is disconnected, and the Bluetooth frequency response and THD curves are displayed on graphs. The operator is then prompted to connect the wired analog input into the Bluetooth speaker, and the same measurements are performed using the analog connection. Analog frequency response and THD curves are temporarily displayed on graphs, followed by graphs containing both Bluetooth and analog curves for comparison.

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New Production Line Bluetooth Interface

BQC-4148_smallThe new BQC-4148 Bluetooth interface is designed for high volume production line testing of Bluetooth sink devices such as headsets, speakers and car kits. It offers control over the CODEC choice, sample rate, and transmitter power, enabling devices to be specifically tested under the conditions that they need to operate

The unit is rugged and compact, measuring just 30 x 64 x 136mm. With only one connector – a USB for connection to the computer for power and control – it is simple to use and offers minimal potential for incorrect operation. It can be controlled via the USB virtual com port using a command line utility, or from within SoundCheck using the control utility via a system step for simple integration with your test sequences. Although it is less full-featured than its R&D counterpart, the BTC-4148, it is approximately half the cost.

See full details

Bluetooth Testing

This webinar demonstrates how to set up your SoundCheck system properly to test Bluetooth devices such as headsets and headphones. It covers the unique challenges associated with testing these products and how to address them. Presented by Steve Temme, Listen, Inc. Status: Recorded. Watch Webinar