A professional is a member of a profession or any person who earns their living from a specified professional activity. The term also describes the standards of education and training that prepare members of the profession with the particular knowledge and skills necessary to perform their specific role within that profession. In addition, most professionals are subject to strict codes of conduct, enshrining rigorous ethical and moral obligations. Professional standards of practice and ethics for a particular field are typically agreed upon and maintained through widely recognized professional associations, such as the IEEE. Some definitions of "professional" limit this term to those professions that serve some important aspect of public interest and the general good of society.
In physics, sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.
Doctor: It plays music. What's the point of that? Oh, with music, you can dance to it, sing with it, fall in love to it. Unless you're a Dalek of course. Then it's all just noise.
Doctor Who Evolution of the Daleks (2007), written by Helen Raynor.
A thousand trills and quivering sounds In airy circles o'er us fly, Till, wafted by a gentle breeze, They faint and languish by degrees, And at a distance die.
EN 
CS
DE
ES
FR
HU
IT
PL
PT
РУ
SK
TR
УК
AR
中文
