How does the length of a pipe effect the frequency of the sound produced?

The sound produced by a pipe is due to standing waves that are formed in the body of the pipe. The fundamental frequency,f1, produced, is given by the formula : f1=v/2L , where v is the velocity of the wave and depends only on the physical characteristics of the mean (e.g. air density), and L is the length of the pipe. So if the length increases the frequency decreases.