The “seat-dip phenomenon”: Low-frequency thief plagues concert goers
David A. Greenberg · The Journal of the Acoustical Society of America · 1985
Sound propagating at grazing incidence over auditorium seats is known to exhibit anomalous attenuation (as much as 20 dB) at low frequencies. This so-called “seat-dip phenomenon,” is predominantly a quarter-wave resonance associated with the height of the seat backs and is on the order of 112 oct wide, centered at about 150 Hz [T. J. Schultz and B. G. Watters, J. Acoust. Soc. Am. 86, 885–896 (1964) and G. M. Sessler and J. E. West, J. Acoust. Soc. Am. 36, 1725–1732 (1964)]. This frequency range happens to correspond to an orchestra's low end (bassoon, horn, trombone, tuba, cello, and string bass) and so the control of the seat dip is an important factor in the communication of orchestral balance. Toward this end, a simple scale modal was built to investigate this complex sound field, particularly that between the seats. Various model configurations were utilized to investigate the sound pressure and intensity fields.