Lambda

Musicians and Sound Engineers. Musical Notes and Frequencies and Wavelengths.

Now there's an app from dgApps to convert between them all.

The app features a sliding fader to dynamically change frequency, wavelength and musical note, with locks to step through standard third octave frequencies or whole notes. There's also a built in tone generator so you can hear the frequency. A settings section allows for different tuning standards, and variations in the speed of sound.