A number of aspects of the hearing process will be related to the practical world of sound recording and reproduction, and to the evaluation of sound quality. The non-linear frequency response of the ear presents the sound engineer with a number of problems. Conversely, if a signal is replayed at a higher level than that at which it was balanced, it will have an increased bass and treble response, sounding boomy and excessively bright. This also helps to explain why even small differences in reproduction level can give rise to noticeable differences in perceived sound quality. Apart from lateralization of sound sources, the ability to perceive distance and depth of sound images is crucial to our subjective appreciation of sound quality. Distance is a term specifically related to how far away an individual source appears to be, whereas depth can describe the overall front–back distance of a scene and the sense of perspective created.