I made up this chart to show the wavelength of some common audio frequencies. This is based on the speed of sound at seal level @ 72ºF. Here is a link to the calculator http://www.mcsquared.com/wavelength.htm
Hz Inches Feet
10 1356 113 20 680 56.5 30 452 37.66 40 339 28.25 50 271.2 22.6 60 226 18.83 70 193.7 16.14 80 169.5 14.125 90 150.66 12.55 100 135.6 11.3 125 108.48 9.04 150 90.4 7.53 200 67.8 5.65 250 54.24 4.52 300 45.2 3.76 500 27.12 2.26 1000 13.56 1.13 2500 5.42 .452 5000 2.71 .226 7000 1.93 .161 8000 1.69 .141 10k 1.356 .113 10.5k .904 .075 20k .678 .056 30k .452 .037