Ow does the distance from the radius affect the frequency of its sound

My 4000 word essay has to have an aim materials hypothesis method data collection and processing( graphs, tablas and analyzation; also uncertainties that are relative) and conclusion ( the conclusion should state a conclusion with justification, based on reasonable interpretation of data, evaluates weaknesses and limitations, and suggests realistic improvements in respect of weaknesses and limitations.)if is possible use basic language, im a mediocre student of Cs.the bibliogrphy should be varied (scientific magazines, encyclopedias web pages,etc)
thank you.