Use the Harman Target Curve to Predict Headphone Preference

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Screenshot from SoundCheck showing the Harman Target Curve being used to predict listener preference ratings of headphones

The Harman Target Curve is used to predict listener preference of headphones

In their landmark papers “A Statistical Model that Predicts Listeners’ Preference Ratings of In Ear Headphones – Parts 1&2” presented at the AES 143rd in October 2017, Sean E. Olive, Todd Welti, and Omid Khonsaripour of Harman International introduced a model that predicted listener preference ratings of headphones based on the Harman Target Curve. We have created a SoundCheck sequence that measures any headphones and predicts the listener preference rating based on comparing its measured results to the Harman Target curve using this model. Listen acknowledges and thanks the authors of the Harman paper for providing the spreadsheet which is used as the basis for the excel template used in this sequence.

This sequence, inspired by the Harman research referenced above, 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.

Check out our short video where we demonstrate this sequence in action

Get the test sequence for predicting headphone preference based on Harman Target Curves

Learn more about headphone testing using SoundCheck

References
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
A Statistical Model that Predicts Listeners’ Preference Ratings of Around-Ear and On-Ear Headphones

 

Active Noise-Cancelling Headphone Battery Life Test

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ANC battery life sequence screenshotThis SoundCheck test sequence measures the performance characteristics of Active Noise Cancelling headphones (ANC headphones) while monitoring the DC voltage and current provided to the headphone by its batteries. The sequence first measures the passive attenuation of the headphone before moving into a loop. The loop plays a 2 minute pink noise stimulus at high output level to accelerate battery drain. During this stimulus period, a current measurement is made by Listen’s DC Connect. Immediately following the stimulus, battery voltage is measured followed by acquisition and analysis of audio parameters (response, THD and THD Normalized). The active attenuation of the headphone is then measured followed by a series of post processing and Autosave steps. The looping continues until no output is detected from the headphone, when the device shuts down due to insufficient battery capacity.

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Headphone Active Noise Cancellation Test Sequence

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Screenshot of the final test result for active noise cancellation headphone test, showing active, passive and total attenuation.This SoundCheck test sequence measures headphone active noise cancellation (ANC). It measures both the active and passive noise cancellation and calculates total attenuation over the operating frequency range of the headphones. Passive Attenuation is the amount of noise that is reduced at the ear simply by the headphones being worn. Active Attenuation is the amount of noise that is further reduced by turning on the device’s active cancellation circuits. Lastly, Total Attenuation is the combined reduction in noise from passive and active sources and is what the end user of the product will experience.

To calculate these metrics this SoundCheck test sequence performs three separate measurements using a Head and Torso Simulator and a small speaker which serves as a noise source. This is a simple, low-cost alternative to using a diffuse background noise environment with multiple speakers playing uncorrelated noise, although the sequence could be user-modified to support this.

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