What is the dfifference between sound frequency and sound speed?

and why does the frequency of sound remain unchanged through time? Surely if a source emits a sound of frquency 440 hz , the sound vibrations(particles) at the beginning will be moving more rapid due to more energy near the beginning of the source but furhter ouyt the particle vibrations will be less rapid due to loss of energy, wouldnt that mean less vibrations hitting the ear result in a change in frequency?