Modes, Standing Waves and Harmonics
A room mode occurs, in the simplest case, when the distance between two parallel walls is equal to the wavelength of a particular frequency of sound.</p>
<p>If the room is excited at this particular frequency a standing wave is set up between these two walls. This particular frequency will be accentuated as a result, causing an uneven tonal balance of sound. Small regular shaped rooms are particularly bad for this as room dimensions often coincide with the wavelength of low to mid frequency sounds.</p>
<p>Harmonics are exact multiples of a particular (fundamental) frequency. A pure sine wave has no harmonics. Most sounds will have harmonic content but may not be a significant contributor to the overall sound.