Gustav Fechner (1801-1887), “Father of Psychophysics.”

Psychoacoustics is the branch of psychophysics involving the scientific study of sound perception.

It is the branch of science studying the psychological and physiological responses associated with sound. Generally, there two sides to psychoacoustics, physical phenomena related to sound, and their counterparts in human perception. The physical side is referred to as “sound source”, and “sound event”, and the perceptual counterparts are then auditory source and auditory event (Blauert, 1996; Pulkki & Karjalainen, 2015). A sound source produces sound typically by mechanical vibrations and a specific occurrence when a source produces sound is called a sound event.
 
The fundamental perceptual unit in hearing is the ‘auditory object’. Auditory objects are the computational result of the auditory system’s capacity to detect, extract, segregate, and group spectrotemporal regularities in the acoustic environment; the multitude of acoustic stimuli around us together form the auditory scene (Bizley & Cohen, 2013). Every auditory object has spectrotemporal properties that make it unique from other auditory objects. Auditory scene analysis refers to the ability to perceive separately sounds coming from different sources. The sound events have certain physical attributes, such as pressure, spectrum and others. The attributes of auditory events depend on attributes of sound events, though in a non-linear way with many factors involved. The simplest dependency is shown with the equal loudness contours. The formation of auditory events are also affected by such factors as sounds heard before, state of mind, and expectations (Dick et al., 2016; Zacharov, 2019). A psychophysical function describes projection from the attributes of sound event and an attribute of an auditory event. An example, “loudness” is one attribute of a sound event and depends primarily on the SPL of the sound event, but also on other factors such as frequency content of sound event, duration of sound event, previous sounds events, and cognitive effects.
 
 
 
Dick, F., Krishnan, S., Leech, R., & Saygin, A. P. (2016). Environmental Sounds. In Neurobiology of Language (pp. 1121-1138). Elsevier. http://doi.org/10.1016/B978-0-12-407794-2.00089-4
 
Blauert, J. (1996). Spatial hearing: The psychophysics of human sound localization. The MIT Press.
 
Bizley, J. K., & Cohen, Y. E. (2013). The what, where and how of auditory-object perception. Nature Reviews Neuroscience, 10, 693-707. https://doi.org/10.1038/nrn3565
 
Pulkki, V., & Karjalainen, M. (2015). Communication acoustics: An introduction to speech, audio and psychoacoustics. Wiley.
 
Zacharov, N. (2018). Sensory Evaluation of Sound (1st Edition ed.). Taylor & Francis Group. https://doi.org/10.1201/9780429429422