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Acoustic phonetics studies speech as a physical sound wave. A microphone records a signal related to changing sound pressure; analysis asks how its amplitude, timing and frequency content vary. A waveform displays variation over time, whereas a spectrogram displays the distribution of signal energy across both time and frequency.

For an original comparison, record a sustained vowel followed by a sustained hiss. Inspect each waveform at the same time scale and compare their spectrograms. Approximately repeated vocal cycles can give a harmonic structure, while the hiss provides an example of a noisier excitation. Broad spectral concentrations associated with the vocal tract are formants; they should be distinguished from the fundamental frequency of a repeating source. The spectrogram's analysis-window duration affects which temporal and spectral details are visible.^[ref]

These are measurements of the signal, rather than direct readings of a listener's perceived pitch or a speaker's tongue position. Relating the signal to perception and production requires auditory phonetics and articulatory phonetics.

Articulatory phonetics studies how the moving structures of the vocal tract produce speech. Airflow supplies energy; vocal fold vibration can provide a repeating source; the tongue, lips and other articulators shape or interrupt the flow. Producing voice and shaping recognizable speech are related but distinguishable processes.^[ref]

A simple observation compares a sustained “mmm” with a sustained “sss”. Lightly touching the outside of the throat can help detect the vibration accompanying voicing, while a mirror shows the different lip configurations. This is a qualitative demonstration: the external sensation alone does not measure the detailed motion of the vocal folds.

Descriptions of consonants commonly distinguish place of articulation, where a constriction is formed, from manner of articulation, how the airflow is modified. These descriptions explain why changing the tongue or lips can change the recorded sound without changing the source of airflow. Acoustic phonetics measures the resulting signal, while articulation describes its physical production.

Auditory phonetics investigates how listeners hear and interpret the physical sounds of speech. The input is an acoustic signal, but the outcome is a perceptual response: identifying a sound, discriminating two recordings or judging their similarity. It connects acoustic phonetics to hearing and to learned phonetic categories.

A simple controlled listening experiment presents pairs of recorded sounds in a randomized order and asks whether they differ. A separate identification task asks which category each recording belongs to. The tasks answer different questions: a listener can detect a physical difference without assigning the recordings to different phonemes. Praat supports forced-choice listening tasks, including same–different and AXB discrimination designs.^[ref]

The sound history presented to a listener can also matter. In Jessica Maye's infant study with collaborators, different exposure distributions along a speech-sound continuum produced different later discrimination patterns. The result concerns the tested exposure and task, rather than a complete account of how a language's sound system develops.^[ref]

Canadian English names English varieties used in Canada, with variation across regions, communities and speakers. For a scientific account, a pronunciation feature must be operationalized and measured rather than treated as a property shared identically by every speaker. Sociolinguistics and acoustic phonetics provide complementary methods for those comparisons.

An acoustic study by Sky Onosson compared Canadian, American Western and American Northern speech through vowel durations and formant trajectories, examining Canadian raising and the effect of a following consonant's voicing.^[ref] A useful replication would record comparable words and contexts, align vowel intervals, and compare trajectories under a stated time normalization. That separates a pronunciation's changing acoustic shape from differences caused merely by speaking rate or the analysis point.

A labiodental consonant forms its principal constriction between the lower lip and upper teeth. This is a place of articulation, distinct from the two-lip constriction of a bilabial consonant. It does not by itself specify voicing or manner of articulation.^[ref]

The familiar sounds [f] and [v] are labiodental fricatives. Comparing them keeps the constriction location similar while changing the usual voicing category. Comparing [f] with [p] instead changes both the contact surface and the airflow mechanism. A mirror can show lower-lip contact with the upper teeth, while acoustic phonetics examines the resulting noise and periodicity.

A phonetician studies the physical production, transmission or perception of speech. Articulatory phonetics investigates the moving vocal tract, acoustic phonetics measures recorded sound, and auditory phonetics studies listeners' responses. One research question can require evidence from more than one of these stages.

For example, a phonetician investigating a vowel contrast can record repeated tokens, estimate formants and test whether listeners distinguish the recordings. Speaker variation and analysis settings must be controlled or measured before differences are attributed to the contrast. Praat provides tools for waveform, spectrogram, pitch contour and formant analysis, making several of these observations reproducible.^[ref] The profession therefore connects language questions to instruments, explicit annotation rules and testable measurements.

Phonetics studies the physical production, transmission and perception of speech. Articulatory phonetics examines the moving structures that shape the airflow; acoustic phonetics examines the resulting sound waves; auditory phonetics examines how a listener perceives them. These are different measurements along the same communication chain.

During voiced speech, airflow from the lungs drives vocal fold vibration. Movements of the tongue, lips and other parts of the vocal tract shape the emerging sound. This separates the production of a vibrating source from the articulation of recognizable speech, and both from the language expressed by it.^[ref]

A simple acoustic comparison records the same spoken phrase twice, once as a statement and once as a question. The sound pressure time series and its spectrogram allow changes in fundamental frequency, segment duration and pauses to be compared. The comparison investigates physical differences in prosody; the written words alone do not specify those measurements.