High-definition quality audio was initially developed to be a differentiator between different levels of quality headphones in the marketplace. Because there was not specific benchmark set to define HD audio, the term has moved to more for a marketing term than a technical spec.

Through scientific study, we’ve put together a team of experts to benchmark what is means to be HD quality. To help differentiate what is quality HD audio and what isn’t, we developed an HD Quality UL Mark. Consumers can look for this mark to validate their purchase meets the requirements.


What type of testing do you do in the audio lab?

To test for HD quality, we conduct what we call an objective test. During this test, we place headphones on a dummy and torso. The head and torso system them measures the frequency emitted by the product.

But, we don’t stop there. We take the testing a step further to conduct what we call a subjective test.

What’s a subjective test?

If you’ve ever tried on headphones at the store, you’ve probably noticed they sound different. Many headphones actually ‘color’ music, or what the music engineered produced to bring out certain sounds. One set of headphones may be better suited for rap music, while another may be better suited for classical.

Subjective testing helps manufacturers better understand the consumer’s experience while using the headphones. To do this, we create a panel of 50 people and an industry professional. We have each participant complete a questionnaire of about 40-50 questions while listening different types of music. Then, we create a report for the manufacturer to show findings and what people think about the sound quality of the headphones.

One example of how a manufacturer may find this helpful is through achieving desired bit rates. Research has found that different bit rates and genres of music actually resonate within the body, which in turn releases adrenaline. When marketing headphones, some companies may find it beneficial to capitalize on that experience. Our subjective testing provides insight into how consumers perceive those experiences — how the music sounds, it makes them feel, etc.

How are you eliminating bias?

We found that people rate based on preference to music genre. To eliminate bias, about 10 of those 40-50 questions actually take into account preferences. Then, we use a variety of songs in each genre to test the headphones.

YouTube video of audio testing at UL