Tuesday, January 28, 2014

Interview in Professional Sound: The Lack of Meaningful Loudspeaker & Headphone Specs

Last October,  I was in Toronto giving a presentation to the local AES section on the perception and measurement of headphones. After the talk, I sat down with Mike Raine from  Professional Sound for an interview. Some of what we discussed is summarized in this article called Sound Advice.

The theme of article is a recurring one that I've discussed before in this blog (see "The Science and Marketing of Sound Quality" and "What Loudspeaker Specifications are Relevant to Sound Quality?").  The bottom line is that the loudspeaker and headphone industry has utterly failed to provide consumers meaningful product specifications that indicate how truly good (or bad) the products sound. Read on to find out why.

Monday, January 6, 2014

Do Listeners Agree on What Makes a Headphone Sound Good?

This past weekend, I attended the ALMA 2014 Winter Symposium in Las Vegas where I gave a talk entitled, "The Perception and Measurement of Headphone Sound Quality: Do Listeners Agree on What Makes a Headphone Sound Good?" The presentation gives a summary of some key findings of our headphone research conducted over the past 18 months. It also includes some unpublished preliminary findings from a current study on headphone preferences of trained and untrained listeners both young and old from China, Canada, USA, and Germany. The focus of this study is to determine whether listeners from different cultures and age groups prefer the same headphone sound quality as trained listeners when the influence of headphone brand, fashion and celebrity endorsement are removed from the test. 

The abstract for my talk is reproduced below. A PDF of the slide presentation can be downloaded here:

The popularity of headphones has now exploded to produce annual worldwide sales of almost $10 billion. Premium headphones ($100+) now account for 90% of the annual revenue growth, as consumers’ audio experiences are becoming a primarily mobile one. Market research indicates sound quality is a driving factor in headphone purchases with brand and fashion also being important factors among younger consumers. Yet, ironically the science behind what makes a headphone sound good and how to measure it is poorly understood. This combined with the lack of perceptually meaningful headphone standards may explain why purchasing a headphone today is like playing Russian Roulette with your ears. The magic bullet to achieving more consistent headphone sound quality is science.

We recently conducted a series of controlled double-blind listening tests on popular headphones (both real and virtualized models) to better understand the relationship between their perceived sound quality and acoustic performance [1,3,5]  A second set of experiments measured listener preferences of different headphones equalized to different target curves responses including the recommended diffuse and free-field target curves [2].  A third set of experiments used a method of adjustment where listeners directly adjusted their preferred bass and treble levels of a headphone and loudspeaker equalized to the same in-room target response [4]. In this way, we could measure the variation in individual listeners’ taste in headphone spectral balance, and determine the extent to which the preferred headphone target response should simulate the response of an accurate loudspeaker in a reference listening room.

Together, the results of this research show that when the influence of brand, fashion and celebrity endorsement are removed from headphone tests, both trained and untrained listeners regardless of age and culture, generally agree on which headphones sound best and this correlates to their acoustical performance.

  1. Sean E. Olive and Todd Welti, "The Relationship between Perception and Measurement of Headphone Sound Quality", presented at the 133rd Audio Eng. Soc. Convention, San Francisco, USA, (October 2012).
  2. Sean E. Olive, Todd Welti and Elisabeth McMullin, "Listener Preferences For Different Headphone Target Response Curves",  presented at the 134th Audio Eng. Soc. Convention, Budapest, Hungary, (May 2013).
  3. Sean E. Olive, Todd Welti and Elisabeth McMullin, "A Virtual Headphone Listening Test Methodology", presented at the 51st Audio Eng. Soc. International Conference, Helsinki, Finland, (August 2013).
  4. Sean E. Olive, Todd Welti and Elisabeth McMullin, "Listener Preferences for In-Room Loudspeaker and Headphone Target Responses"  presented at the 135th Audio Eng. Soc. Convention, New York, USA, (October 2013).
  5. Sean E. Olive, "Do college students prefer the same headphone sound quality as trained listeners?", presented at the 4th ISEAT, Shenzhen, China, (November 2013).