The base standard that orchestras tune to:
A4 is the 10th semitone (Octaves start at C) of octave 4
and has a frequency of 440Hz.
You can find the frequency and wavelength of other musical notes
with this free online javascript calculator:
The Frequency of
is 440Hz
which at Temperature °C
(giving a speed of sound of 344.97m/s)
results in a Wavelength of 0.784m
(Note that the speed of sound does not depend on altitude)