Evaluation of Sound Quality of High Resolution Audio
Naoto Kanetada, Ryuta Yamamoto, Mitsunori Mizumachi · 2013
High resolution audio (HRA), which is recorded in the digital audio format with high sound quality, appears on the audio market. HRA has the quality equal to or better than the standard compact disc (CD), and is distributed as the super audio CD (SACD), DVD-audio, Blue-ray audio, and a data file through the internet. In this paper, sound quality of HRA is investigated in the view point of auditory perception. Perceptual characteristics of HRA have been examined by listening tests as compared with the standard audio CD and the compressed MPEG audio layer-3 (MP3) qualities. The listening tests were carried out by the method of paired comparison, and the participants were asked to discriminate among HRA, CD, and MP3. Jazz music, which was sampled at 192 kHz with 24 bits resolution, was selected out as the original HRA. Both CD and MP3 quality audio files were prepared from the original HRA file by the authors. It is found that the participants prefer the audio format with richer information, that is, HRA is most desirable and CD is better than MP3. The participants were also required to fill in the questionnaire on subjective impression for each audio format. Subjective characteristics of HRA include much presence, high spatial clarity, and wide spaciousness. In addition, perceptual discrimination in quantization distortion is also focused on in between 16 bits and 24 bits resolution. As the result of the listening test with 28 participants, the difference of quantization resolution could be discriminated with the accuracy of 60.3 %. Concerning the perceptual discrimination of HRA, it is suggested that quantization resolution is an important factor as well as wide frequency range.