Room standing waves cause sound pressure to vary with listening position

Evidence

Another name for these standing waves in a room is resonant modes, and the frequencies at which they occur are known as “modal frequencies.” Because the modes are spatially static, there will be a strong variation of sound pressure level as one moves around the room, which is undesirable. There are three basic types of room mode, which are outlined in Sections 6.2.1 to 6.2.3. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1953

Another name for these standing waves in a room are resonant modes and the frequencies at which they occur are known as “modal frequencies.” Because the modes are spatially static there will be a strong variation of sound pressure level as one moves around the room, which is undesirable. … These modes occur between two opposing surfaces, as shown in Figure 6.31, and so are a function of the linear dimensions of the room. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1996

Categorization

• DEFINE: Introduces the terms resonant modes and modal frequencies controlling room sound behavior.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1953; David Howard, Jamie Angus, coustics and Psychoacoustics, 1996