A child's train whistle replicates a classic conductor's whistle from the early 1900 s. This whistle has two open-open tubes that produce two different frequencies. When you hear these two different frequencies simultaneously, you may have the perception of also hearing a lower note, called a difference tone, that is at the same frequency as the beat frequency between the two notes. The two tubes of the whistle are \(12 \mathrm{~cm}\) and \(11 \mathrm{~cm}\) in length. Assuming a sound speed of \(350 \mathrm{~m} / \mathrm{s}\), what is the frequency of this difference tone?