Predicting Farfield Pressures from Nearfield Loudspeaker Measurements

Kessel RT. Predicting Farfield Pressures from Nearfield Loudspeaker Measurements. In: AES Convention 85. Audio Engineering Society; 1988. Paper 2729. Available from: https://aes.org/publications/elibrary-page/?id=10235

@inproceedings{Kessel1988_10235,
  author = {Kessel, Ron T.},
  title = {{Predicting Farfield Pressures from Nearfield Loudspeaker Measurements}},
  booktitle = {AES Convention 85},
  note = {Paper 2729},
  year = {1988},
  month = nov,
  publisher = {Audio Engineering Society},
  url = {https://aes.org/publications/elibrary-page/?id=10235}
}

TY  - CPAPER
TI  - Predicting Farfield Pressures from Nearfield Loudspeaker Measurements
AU  - Kessel, Ron T.
T2  - AES Convention 85
M1  - Paper 2729
PY  - 1988
DA  - 1988/11/06
UR  - https://aes.org/publications/elibrary-page/?id=10235
PB  - Audio Engineering Society
LA  - en
AB  - Keele has shown that the low-frequency response of a loudspeaker can be measured in a reverberant room if the microphone is placed in the nearfield of the driver. To predict the on-axis farfield pressures from nearfield measurements, Keele developed a simple nearfield-to-farfield transformation which neglects diffraction of the sound field by the loudspeaker cabinet. In this paper the low-frequency diffractive effects of a loudspeaker cabinet are investigated using the Helmholtz Integral Equation. It is found that the diffractive effects on the farfield on-axis pressures depend on the area of the front baffle and the average radius of the front baffle as seen by the driver. A new approximate nearfield-to-farfield transformation is derived which includes the effects of diffraction. The new transformation is found to be suitable for realistic loudspeakers having a conical driver and spherical dust cap.
ER  -