Sound waves are different than light energy waves. Sound waves require a medium to pass through. Light waves can pass through a vacuum but sound waves cannot. Sound waves need molecules to travel through, be they in a solid, liquid, or gas (the atmosphere). The molecules in the medium that sound wave pass through are displaced by the waves. This molecular motion requires energy from the wave, thus the sound wave gets weaker over time as it travels and eventually loses all of its energy and dissipates. Other than this, sound waves are like other waves in that they are sinusoidal in nature, with amplitude, wavelength, and frequency.
The best way to define a note on sound waves is their frequencies. It characterized on how they ascend or descend depending on the given pitch. for example the low note like A#0/Bb0 has a frequency of 29.1352, the C5 (C tenor) has a frequency of 523.251, the C6 ( C soprano) has a frequency of 1046.50 and lastly the last note C8 has a frequency of 4186.01. Furthermore, their frequency called Hertz (Hz). a number of cycles per second. It was derived after the name of Heinrich Rudolf Hertz.