Noise criteria and office communication. Finally, it is necessary to come to grips with the distinctions between sound and noise. Any sound within the region of perception may in some circumstances be noise. The upper levels may be precisely assessed in terms of pain, impairment of hearing or interference with speech communication. This leaves the vague, indefinable, but nonetheless important category of annoying or disturbing sounds.
Few sounds are intrinsically unpleasant.
They become so if they intrude sufficiently on a listener's consciousness to distract him from his own pursuits. The listener must first be able to hear the intruding noise above the other ambient noises in his own environment. In addition, it must attract his reluctant attention. This requires that the sound have some special character, usually denoting a specific activity. Speech sounds are particularly troublesome if they are intelligible or nearly so.