Acoustic and Auditory Phonetics
Acoustic and auditory phonetics study the physical properties of the speech signal and how the ear and brain receive and interpret those properties.
Definition
The branches of phonetics concerned with the physical acoustics of the speech signal and with how it is perceived by the auditory system.
Scope
This area covers the acoustic side of speech: the nature of sound waves, the spectral analysis of the speech signal, and the relation of acoustic patterns to articulation through the source-filter model. It treats the acoustic cues—formants, voice onset time, spectral shape, and timing—that differentiate speech sounds, as well as the auditory side: how the auditory system transduces and processes these signals and how listeners recover linguistic categories from a variable, continuous signal. The treatment is descriptive and grounded in the physics of sound and the psychology of perception.
Sub-topics
Core questions
- What acoustic properties characterize speech sounds?
- How does the source-filter model relate articulation to acoustics?
- Which acoustic cues do listeners use to distinguish sounds?
- How does the auditory system convert the speech signal into linguistic categories?
Key theories
- Source-filter theory of speech production
- Gunnar Fant's account that the speech signal results from a sound source (such as vocal-fold vibration) filtered by the resonances of the vocal tract, which shape the spectrum into formants.
- Quantal theory
- Kenneth Stevens's proposal that the nonlinear relation between articulation and acoustics produces stable acoustic regions, helping explain why certain articulatory configurations and distinctive features recur across languages.
History
Acoustic phonetics expanded rapidly after World War II with the invention of the sound spectrograph, which made the spectral structure of speech visible. Gunnar Fant's source-filter theory and later work at Haskins Laboratories and by Kenneth Stevens established the field's theoretical foundations, while auditory phonetics drew on advances in psychoacoustics.
Debates
- Invariance and the lack of one-to-one cue mapping
- A central problem is that the acoustic signal for a given phoneme varies with context and speaker, raising the question of how listeners achieve stable perception without invariant acoustic cues.
Key figures
- Gunnar Fant
- Kenneth Stevens
- Keith Johnson
Related topics
Seminal works
- fant1960
- stevens1998
- johnson2012
Frequently asked questions
- What is a spectrogram?
- A spectrogram is a visual representation of the speech signal that plots time on the horizontal axis, frequency on the vertical axis, and intensity by darkness, making formants and other acoustic features visible.
- What is the difference between acoustic and auditory phonetics?
- Acoustic phonetics studies the physical sound wave produced in speech, whereas auditory phonetics studies how the ear and brain receive and process that sound to recover linguistic information.