Sound quality assessment is a sound measurement process whereby the sound characteristics are the unknown quantity and the listener is the measuring tool. This concept of sound assessment applies to both signal quality and noise quality studies. The groups of listeners assessing sound quality in such studies are called listening groups. The listening groups are usually small and frequently created on an ``ad-hoc'' or statistical basis. This is an unfortunate situation because human auditory capabilities vary greatly among individuals and depend on the psychophysiological profile, experience, and listening skills of the listener. Therefore, the composition of the listening group should be considered the primary factor affecting the results of sound quality assessment. To increase the practical value of sound quality studies, the issue of selection and training of the listeners must be given more attention. For example, it should be recognized that sound quality studies are different from marketing studies and need to involve uniform groups of listeners. It is also imperative that the difficulty and complexity of the listening tasks are proportional to the listener's auditory skills and knowledge of the subject matter.