For example if one note is twice the frequency of another, we say it has a pitch one octave higher . If the frequency is doubled again, the note goes up another octave. So the series f, 2f, 4f, 8f etc is a series of notes rising by an octave each time. A note consisting of just one frequency is called a pure tone and does not occur often when musical instruments produce tones. A tuning fork or electronic device may produce pure tones.
Most instruments however produce notes which are more complex.
Within one note there is a blend of frequencies present. The nature of the blend determines what we hear and how we describe that tone. If there is no recurring pattern to the frequencies present, ie no one frequency dominates, then we hear the sound as a flurry of vibrations, or noise. If there is only one steady frequency present, we have a pure tone. If there is a single sound with several frequencies present , we can usually hear a plurality of frequencies but we assign a pitch to the dominant one.