This sequence, inspired by AES papers on statistical models to predict listener preference by Sean E. Olive, Todd Welti, and Omid Khonsaripour of Harman International, applies the Harman target curve for in-ear, on-ear and over-ear headphones to a measurement made in SoundCheck to yield the predicted user preference for the device under test. The measurements are made in SoundCheck and then saved to an Excel template which performs the necessary calculations to produce a Predicted Preference score using a scale of 0 to 100. The spreadsheet calculates an Error curve which is derived from subtracting the target curve from an average of the headphone left/right response. The standard deviation, slope and average of the Error curve are calculated and used to calculate the predicted preference score. The sequence also provides the option to recall data rather than making a measurement, which saves time for engineers who already have large quantities of saved data, and enables historical comparison with obsolete products.
Over 150 people attended the Listen, Inc./G.R.A.S. headphone seminar in Seoul on Tuesday March 6th, where Steve Temme, Peter Wulf-Andersen, Dr. Sean Olive and Prof. Lee spoke to a packed room about headphone measurement, perception and design and tuning. It was a great event and exciting to meet so many of Korea’s top audio design engineers. Thank you for coming! And of course a huge thank you to our very special guest speakers, Dr. Olive and Prof. Lee.
Videos of the event (in English and Korean) can be viewed using the links below (videos will open in a new tab).
Peter Wulf-Andersen – G.R.A.S.: https://youtu.be/sTZpShVDaoI
Steve Temme – Listen, Inc.: https://youtu.be/35TtshAENdo
Prof. Lee – New Media Communication Joint Institute of Seoul National University: https://youtu.be/mhLW03PvLmw
Dr. Sean Olive, Harman International: https://youtu.be/B8cNf0Q3tNs
This 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.
Due to popular demand, we are now holding our headphone testing seminar in Chicago and Boston!
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 and lunch will be provided. Space is limited, so please RSVP today.
Locations and Dates:
Chicago: Friday October 13th, DoubleTree by Hilton Hotel Chicago Wood Dale-Elk Grove, 1200 N Mittel Blvd, Wood Dale, IL 60191
Boston: Monday October 16th, Hilton Garden Inn, 450 Totten Pond Rd, Waltham, MA 02451 NOTE: THIS VENUE HAS CHANGED. DUE TO HIGH DEMAND FOR THIS SEMINAR WE HAVE HAD TO MOVE IT TO A LARGER VENUE. Note that this is 2 days before the start of the AES show in New York – a short flight or 3.5 hour train ride away. Consider combining this informative seminar with your AES travel!
See what people are saying about this event (we presented similar earlier in the year on the West Coast)
- 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
- Traditional tools vs. modern consumer demands
- 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
- 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
This sequence tests a stereo headphone connected to a portable audio device such as a mobile phone or MP3 player. It is particularly useful for testing headphones with proprietary connectors such as the Lightning connector which otherwise can’t be tested in a conventional “closed loop” test configuration.
The test stimulus is created in SoundCheck, saved as a WAV file and loaded on to the portable device for playback. Both left and right earphones are measured simultaneously using a continuous log sweep from 20 Hz to 20 kHz. The sequence uses a short 1 kHz tone, pre-pended to the normal test stimulus to automatically trigger the test when playback of the test signal begins; it also serves as reference tone for any frequency shift calculations. Post-processing precisely synchronizes the stimulus and response waveforms, and then calculation of the measurement parameters proceeds as with any conventional headphone. In this case, analysis is performed using the Time Selective Response (TSR) algorithm which performs THD and fundamental frequency response analysis simultaneously in addition to producing an impulse response. The fundamentals are then post processed to derive the sensitivity of the left and right channels at 1 kHz.