In this investigation experimental studies on the acoustic resonance are undertaken. In the first place the effect of the pitch of tubes on Strouhal number or the nondimensional acoustic resonance frequency is studied in a wind tunnel test using many model banks. According to the result the Strouhal number increases with a decreasing pitch of tubes. In the second place a two-dimensional model basin test is undertaken and putting together the theory on the single tube in a flow previously reported and the observation result on the model basin test, a self-iduced vibration theory for the acoustic resonance is proposed.