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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.

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 consonant is a speech sound articulated with a closure or constriction that significantly shapes or interrupts airflow. Its physical description typically specifies place of articulation, manner of articulation and voicing. These describe where the articulators act, how the air passes and whether the vocal folds vibrate.^[ref]

The sounds [p] and [b] both involve the lips and a closure, but differ in their usual voicing classification. A sustained [m] also closes the lips, while opening a route through the nose: an oral closure does not imply that all airflow stops. The distinction between a plosive and a nasal consonant therefore depends on airflow paths, not merely the fact that two lips touch.

The category concerns speech sounds, rather than letters: a written symbol's name and its sound in a particular word are different objects of study. A consonant can also function as a syllabic consonant, so a syllable nucleus is not invariably a vowel.

A consonant cluster is a sequence of multiple consonants without an intervening vowel, considered within the chosen phonological representation. Its possible position and composition depend on a language's phonotactics. The written number of consonant letters is insufficient to identify a spoken cluster.

In an ordinary pronunciation of “stay”, [st] forms a syllable onset cluster; the final [ts] in “cats” forms a syllable coda cluster. By contrast, the English spelling ch can represent one affricate, transcribed [t͡ʃ], rather than two independently combined consonants. This comparison distinguishes spelling, phonetic detail and phonological grouping.^[ref] A recording and explicit transcription make the analysis inspectable; rapid articulation need not insert a silence between the cluster's members.

David Weenink co-created Praat with Paul Boersma, providing tools for measuring and modeling speech. His 2006 thesis investigated speaker-adaptive vowel identification: how recognition can remain useful when acoustic patterns vary between speakers.^[ref][ref]

The thesis describes recordings from 30 speakers, each producing 12 Dutch vowels in controlled sentence frames. It relates these data to formants, principal component analysis, discriminant analysis and adaptive classification methods. This makes the recognition problem experimentally concrete: a classifier must separate vowel identity from speaker-related variation rather than memorize a single speaker's frequency spectrum.^[ref]

Homepage: www.fon.hum.uva.nl/david/

Derek Denis is a linguist studying language change and variation, particularly Canadian English. His University of Toronto Mississauga profile describes using archival oral-history recordings to investigate earlier Ontario English and studying how Toronto's multilingual communities contribute to emerging speech patterns.^[ref]

The recordings make the comparison empirical: observed pronunciations and usages can be related to speakers and historical settings rather than inferred solely from spelling. His work in sociolinguistics asks how innovations arise and spread. A listed study of Toronto vowels connects that question to measurable sound patterns. He is a coauthor of Essentials of Linguistics (2nd edition) by Catherine Anderson and others.

A diphthong is a vowel whose quality changes during its production, conventionally treated as one dynamic vowel unit. A monophthong has relatively stable quality instead. The vowel in English toy, often transcribed [ɔɪ], moves from a back rounded quality toward a high front unrounded quality.^[ref]

A recording can represent that change through formant trajectories. For an invented illustration, let normalized vowel time be $0\le u\le 1$ and setin hertz. These are stipulated linear interpolation tracks, not measurements of toy. Their endpoints differ even if fundamental frequency stays fixed, separating changing vowel quality from voice pitch. Real trajectories need not be linear, and identifying a single diphthong rather than a sequence of separate vowels requires phonological evidence as well as an acoustic curve.

A formant is a resonant spectral feature associated with the filtering of speech by the vocal tract. Its centre frequency and bandwidth describe different aspects of the feature; the first few formants are conventionally labeled $F_1,F_2,\dots$. Praat represents estimated formant structure as time-sampled centre frequencies and bandwidths.^[ref]

A simple physical model treats the vocal tract as a uniform tube, closed at one end and open at the other. Under those ideal boundary conditions its resonance frequencies arewhere $c$ is the speed of sound and $L$ the tube length. For $L=0.17\mathrm{m}$ and $c=340\mathrm{m}{\mathrm{s}}^{-1}$, the first three model resonances are 500, 1500 and 2500 hertz. A real vocal tract has a varying cross-section, losses and moving articulators, so this illustrates the mechanism rather than predicting every vowel.

These resonances are distinct from the fundamental frequency of vocal fold vibration. The source-filter model separates the repeating excitation from the filter's spectral envelope, explaining how a speaker can change vowel quality without making the same change in pitch.

A lip is a movable fold at the entrance to the mouth, with skin externally and oral mucosa internally. The lips contain the orbicularis oris muscle, whose contraction helps close and shape the oral opening. Their sensory supply helps guide contact with food and objects.^[ref]

The oral seal has several functions. During eating it helps retain food; during speech, closure and release can interrupt airflow, while rounding changes the geometry of the vocal tract. A bilabial stop such as /p/ uses contact between both lips, whereas a rounded vowel uses an open but reshaped outlet. The visible fold and the muscle controlling it are related structures, rather than identical anatomical objects.

Lip rounding is the narrowing and reshaping of the lip opening, often with protrusion, used in producing some vowels. Rounded and unrounded configurations alter the acoustic filtering of the vocal tract. Lip rounding is distinct from vowel height and vowel backness, even though particular languages commonly associate these properties.^[ref]

Compare [i] with [y]: both are close front vowels, while [y] is rounded. A mirror makes the lip difference visible; a recording permits their formants to be compared. Keeping the intended tongue position and pitch similar helps separate the manipulation from simultaneous changes. The unrounded/rounded label is a concise category, while actual movements and the opening's geometry vary continuously.

A monophthong is a vowel with relatively stable quality through its central portion, in contrast with a diphthong's substantial movement between qualities. Relatively stable does not mean physically unchanging: neighboring sounds, vocal tract movement and the analysis interval can all affect a recording.^[ref]

For a stipulated acoustic illustration, hold the first two formants at $F_1=300$ and $F_2=2200$ hertz, while varying fundamental frequency from 100 to 150 hertz. The model changes voice pitch without requiring the same change in the formant pattern. Conversely, changing formants can change vowel quality while fundamental frequency stays fixed.

An experimental analysis can record a sustained vowel and compare several points within a consistently chosen interval. Changes concentrated near consonant boundaries need not make the whole segment a diphthong. The distinction therefore combines a phonetic trajectory with an analysis of the language's sound units.

Praat is software for analyzing, synthesizing, annotating and manipulating speech, created by Paul Boersma and David Weenink. It makes the connection between a recorded acoustic signal and measurable speech properties explicit: a waveform, a spectrogram, a pitch contour and estimated formants describe different aspects of the same recording.^[ref]

For a sustained vowel, one can compare the repeating structure of the waveform with the estimated fundamental frequency, then examine how the frequency spectrum is shaped by the vocal tract. A change in vowel quality need not be a change in pitch. Annotations can align intervals with phonemes or syllables without treating every acoustic boundary as an unambiguous linguistic boundary.

Measurements depend on the analysis settings and the signal. In particular, a displayed pitch contour can contain octave errors, while estimated formants depend on the analysis model. Inspecting the recorded sound and analysis assumptions is therefore part of the experiment, rather than accepting every displayed trajectory as ground truth.

Sky Onosson is a linguist whose research connects phonetics, phonology and quantitative analysis of language variation. His research statement emphasizes the changing acoustic structure of vowels, including diphthongs, and the use of the R for modeling and visualization.^[ref]

His 2018 dissertation investigated Canadian raising by comparing vowel duration and formant trajectories across Canadian and two American dialect groups.^[ref] Comparing a trajectory instead of only one instant helps distinguish a vowel's changing quality from the effects of duration. His work consequently treats time alignment as part of the scientific analysis, rather than assuming that measurements at a single relative time capture every contrast.

Homepage: onosson.github.io/

A syllabic consonant is a consonant functioning as a syllable nucleus. Consonant articulation and nuclear position describe different properties, so the combination is not contradictory. In phonetic transcription, a mark below the symbol can indicate syllabicity, as in [n̩].^[ref]

Some pronunciations of English “button” use a final syllabic [n̩]; others contain a vowel before the final nasal. The first pattern does not require an unrecorded vowel simply because the word has a second syllable. Listening and inspecting the acoustic interval can help distinguish the realizations, while identifying a syllable boundary is not equivalent to finding a silent gap in the waveform.

A syllable organizes speech sounds around a syllable nucleus, often a vowel. A preceding syllable onset and a following syllable coda can surround that nucleus. These components describe the organization of speech, rather than a requirement to pause between successive units.^[ref]

For example, in a simple pronunciation of “cat”, [k] occupies the onset, [æ] the nucleus and [t] the coda. A syllable can have an empty onset or coda, so the example's three-part form is not a mandatory template for every word. A syllabic consonant can also serve as a nucleus.

The distinction matters in speech rhythm: counting letters, counting phonemes and identifying syllables are different operations. Physical measurements of duration and pitch contours can be related to syllable organization, but they do not imply a silent gap at every proposed boundary.

A syllable nucleus is the central constituent around which a syllable is organized. It is commonly a vowel, but a syllabic consonant can fill that role. The term describes organization in phonology, rather than a requirement that every nucleus have one particular articulatory mechanism.^[ref]

In a simple pronunciation of “cat”, [æ] is the syllable nucleus, between the syllable onset [k] and syllable coda [t]. A vowel-only syllable can have a nucleus without either margin. Finding the loudest sample in a recording does not define its nucleus: acoustic amplitude, duration and abstract constituency are different descriptions of speech.

A syllable onset is the constituent preceding the syllable nucleus within a syllable. It may contain one consonant or a consonant cluster, and some syllables have no onset. A language's phonotactics constrains which combinations can occupy that position.^[ref]

In “cat”, [k] is a simple syllable onset; in “stay”, [st] forms a cluster before the vowel. A vowel-initial pronunciation can instead begin directly with the syllable nucleus. This is a statement about spoken structure: the number of written initial letters need not equal the number of onset consonants, and no physical pause is required at every syllable boundary.

A velar consonant forms its main constriction between the back of the tongue and the soft palate. The label identifies a place of articulation. The soft palate's separate role in controlling the nasal airflow route means that velar place does not itself imply a nasal manner of articulation.^[ref]

The sounds [k] and [g] are velar oral stops, while [ŋ] is a velar nasal consonant. All involve a similar oral constriction region, but they differ in airflow route and usual voicing. The precise contact position can also shift with neighboring vowels. Describing a region of contact is therefore more informative than imagining one fixed point used identically in every utterance.

The vocal tract is the air passage above the sound-producing region of the larynx, including the pharyngeal, oral and, when acoustically coupled, nasal cavities. Movements of the tongue, lips, jaw and soft palate change its shape. These changes help turn a laryngeal sound source or a turbulent air stream into distinguishable speech sounds.^[ref]

A simple acoustic model treats an unbranched tract of length $L$ as a uniform tube closed at one end and open at the other. A pressure maximum at the closed end and pressure minimum at the open end allow odd quarter wavelengths, givingWith $L=0.17$ m and sound speed $c=340$ m/s, these resonances are $500$, $1500$ and $2500$ Hz. A real vocal tract is neither uniform nor permanently closed at the glottis; its varying cross-section and branching shift the resonances. These spectral resonances, associated with formants, differ from the repetition frequency of vocal-fold vibration. This is why changing articulation can change a vowel without requiring the same change in voice pitch.

A vowel is a speech sound produced with a relatively open vocal tract, allowing its configuration to shape the sound without the complete closure or strong constriction characteristic of many consonants. Vowel height, vowel backness and lip rounding describe major articulatory differences. The vocal tract's acoustic resonances help determine the resulting formants.^[ref]

For example, [i] is a close front unrounded vowel, whereas [u] is close, back and rounded. Moving between them changes the tongue and lips, even if the fundamental frequency of vocal fold vibration is kept approximately constant. This separates vowel quality from pitch.

Many vowels occupy a syllable nucleus, but articulatory and syllabic descriptions answer different questions: a syllabic consonant can occupy that position too. Written vowel letters are also distinct from vowel sounds; the same spelling can correspond to different pronunciations.