Prediction of Listener Preference of In-Ear Headphones using the Harman Model
A test sequence that applies the Harman target curve for in ear headphones to a measurement made in SoundCheck to yield the predicted user preference for the device under test.
The purpose of this sequence is to apply the Harman target curve for in 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.
Listen would like to acknowledge Sean E. Olive, Todd Welti, and Omid Khonsaripour of Harman International. This sequence is inspired by their Audio Engineering Society papers “A Statistical Model that Predicts Listeners’ Preference Ratings of In Ear Headphones – Parts 1&2” presented at the AES 143rd in October of 2017. The authors also provided the spreadsheet which was used as the basis for the Excel template in this sequence to perform the preference calculations.
A Statistical Model that Predicts Listeners’ Preference Ratings of In-Ear Headphones: Part 1—Listening Test Results and Acoustic Measurements
A Statistical Model that Predicts Listeners’ Preference Ratings of In-Ear Headphones: Part 2—Development and Validation of the Model
- 2 channel audio interface – Listen AudioConnect (part # 4050) or similar
- 2 channel microphone power supply – Listen SoundConnect 2 (part # 4025/4026)or similar
- G.R.A.S. RA0045 coupler with 0403 canal extender (see Notes on Running the Sequence (directions tab))
- Headphone amplifier (optional if not using AudioConnect headphone out)
- SoundCheck Basic – version 17 or higher
- Microsoft Excel – version 2010 or higher
Setup & Calibration
- Calibrate your headphone amplifier and HATS ears per the instructions in the SoundCheck user manual
- Connect your audio interface outputs 1 and 2 to the input of your headphone amplifier
- Connect the outputs of your microphone power supply to inputs 1 and 2 of your audio interface
- Connect your HATS to the microphone power supply
- Connect your DUT to the output of the headphone amplifier
You are ready to start the sequence.
Notes on Running the Sequence
- The IE target curve was developed using a G.R.A.S. RA0045 IEC60318-4 compliant coupler. Other common fixtures for testing IE headphones such as B&K 4128, B&K 5218, G.R.A.S. KEMAR, etc. have not been validated against the target and are not recommended for use with this sequence at this time.
- Run the sequence from its folder as it contains recall data, autosave steps and an Excel template using relative paths.
- The Excel file containing the user preference data will be saved to the sequence folder using the file name construction
The preference data will appear on the Report tab.
- When you first run the sequence, you will be asked if you want to recall example curves. If you respond Yes, example curves will be recalled, post processed and the relevant sequence data will be shown on the final display and saved to the Excel spreadsheet for the predicted preference calculations. If you respond No, you will be prompted to input a test level before the sequence continues with the measurement of your DUT.
Further Sequence Development
This sequence has been designed for simplicity and has been written for a two-channel system, to be accessible to 100% of SoundCheck users. Ways in which you could modify or further develop the sequence include:
- Add Distortion and/or Rub & Buzz analysis to the HarmonicTrak analysis step
- Add a separate autosave step for Distortion/Rub & Buzz data
- If desired, remove steps 3 and 4 used to recall example data