A spectroscopic technique based on the photoacoustic effect. A photoacoustic spectrum consists of a plot of the intensity of the acoustic signal detected by a microphone or a 'piezoelectric' detector, against the excitation wavelength or another quantity related to the photon energy of the modulated excitation.
See also: isooptoacoustic point
Source:
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2259 (https://doi.org/10.1351/pac199668122223)