A rectangular room supports infinitely many modal frequencies set by half-wavelength fits

Evidence

This equation shows that there is an infinite number of possible modal frequencies at which an integer number of wavelengths fit into the room, with lowest modal frequency occurring when just one half wavelength fits into the space between the reflecting surfaces. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1959

Categorization

• DEFINE: Defines axial room modes as standing-wave frequencies where an integer count of wavelengths spans the dimension between reflecting surfaces.
• XREF: Connects to the earlier chapters’ treatment of standing waves and half-wavelength resonance conditions.