(a) The sound wave has a period of 3.0 seconds. (b) The sound wave has an amplitude of 1/4. (c) The x-axis is represented by the midline equation. The sound wave's duration The following formula is used to determine the sound wave's period: y = A cos(ωt) wherein y = A cos(2π/T) where A is the sound wave's amplitude and ω is its angular speed. 2π/3 = 2π/T T comes to 3. The wave's amplitude, A = 1/4 The x-axis represents the equation's center.