What is wave speed?

The concept of "wave speed" is at the heart of most descriptions of wave motion, whether qualitative or quantitative. However, (is argued in this paper that the term wave speed is interpreted differently by analysts using different mathematical methods of representing wave mOtion It is shown that, whereas the implications of the inconsistency are often insignificant, that outcome is not guaranteed Furthermore, even if the different usages never had any consequences for practical predictions of wave behaviour, the ambiguous use of terminology inevitably creates communication barriers between disciplines. The discussion begins with a descnprion of simple waves as observed by lay persons and their interpretations have a strong influence on the assessment of the alternative mathematical approaches Overall, in the matter of wave speed, it is shown that lay persons' perspectives coincide more closely with frequency- domain methods than with MOC methods.