Sound systems delivering enhanced spatial reproduction compared with conventional two-channel stereo demand appropriate subjective testing techniques to assess their performance. Sound quality assessment methods of the past 30 years have been mainly concerned with attributes other than spatial, concentrating primarily on timbral and distortion issues when assessing the qualities of loudspeakers or low bit-rate codecs. Spatial attributes, considered an important contributor to overall reproduced sound quality, can be determined by a variety of experimental and statistical means. They may also be related to physically measurable parameters of the sound field. Early work in this field and examples of applications in experimental projects are described and discussed.