Six conclusions were drawn from the experiment:
- Subjects perceived significant differences between the headphone's in the areas of comfort, preferred attributes of sound quality, and spectral balance.
- The most preferred headphones had the least deviation from flat and neutral in spectral balance rating.
- Sound quality attribute preferences and overall spectral balance ratings occurred in separate parts of this two-part test, but there was a strong correlation between perceptions of poor spectral balance and comments associated with low preference rating.
- The more preferred headphones had measurements showing flatter, smoother amplitude response, and better extended bass. The measured amplitude response was generally a good predictor of perceived spectral balance and preference rating.
- The most preferred headphone did not have the 12dB peak at 3kHz which exists in the diffuse field standard curve. Two headphones which did have this peak were judged to be too thin and bright.
- In-ear measurements showed significant variations in amplitude response depending upon the listener and model headphone used. Some headphones varied more than others. How these headphone/listener variations effect the accuracy, reliability, and validity of subjective testing will be explored in future work.