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Question: Describe and illustrate how duration is used as an identifying acoustic cue in two different scenarios: both for fricatives, and for V + C clusters.

17 Jan 2023,8:10 PM


Section A                                                                                                              (40%)

Reading Spectrograms: Being Acoustic Detectives                       (c. 700 words)


In the folder ‘Spectrograms’ under ‘Assignment 3’ on Blackboard are a series of spectrograms and waveforms of a nine-word utterance produced to 10,000 Hz. Each word comprises one syllable apart from word 5, which comprises two syllables. Where word boundaries are important, words have been clustered in the running speech spectrograms:



    1. Whole utterance produced as running speech
    1. Words 1 and 2 produced as running speech
    1. Words 3 and 4 produced as running speech
    1. Words 4 and 5 produced as running speech
    1. Words 6 and 7 produced as running speech
    1. Words 8 and 9 produced as running speech
    1. Words 1 and 2 produced as a mechanical clock
    1. Words 3 and 4 produced as a mechanical clock
    1. Word 5 produced as a mechanical clock
    1. Words 6 and 7 produced as a mechanical clock
    1. Words 8 and 9 produced as a mechanical clock



The sentence resembles a newspaper headline and talks about a once rare bird now being very common in mid-summer.



Your task is threefold: 


  1. To work out as far as possible what is being said, using the evidence presented in the acoustic cues and with reference to materials and literature we have used in the module, plus other source material as necessary. You MUST contact me with your deductions and rationale before you go on to points 2 and 3, ideally before class in Week 12.
  2. To write a brief commentary (c. 700 words) on the acoustic evidence to justify your deductions, integrating appropriate source material as necessary.
  3. To produce a detailed phonetic transcription to facilitate your commentary discussion, based on the characteristics and acoustic cues you have highlighted on the spectrograms such as:


  • Voice bar
  • Amplitude and length features
  • Formant readings
  • Formant transitions
  • High frequency turbulence
  • VOT



Go through the spectrograms systematically, highlighting acoustic evidence for:


  • Fricatives – how they compare in terms of duration, diffusion, frequency location, whether there is a voice bar etc.
  • Plosives – the presence of VOT, of a voice bar etc.
  • Vowels – compare F1, F2 of the different vowel qualities, including diphthongs
  • Approximants – if there are any, find the acoustic cues.
  • Think about CVC syllable structure and examine onsets and codas.
  • Write down all potential sounds for each feature in order to see what is possible and not possible lexically.





Section B

Knowledge of Acoustic Phonetics                                                                                       

You MUST answer Question 1, and ONE OPTION from Question 2.


Question 1                                                                                (c. 700 words)  (40%)        

  • Briefly explain speaker-hearer theory of the speech chain, with illustrations and examples to clarify the discussion.                                                       (15%)
  • Produce a speech transmission level representation and phonetic transcription of the declarative statement ‘I don’t know’ uttered in a careful speech style. How does the detail of both change in a very casual speech style?                  (10%)
  • What segmental/suprasegmental features can we use to alter the informative meaning of this statement to make it exclamatory?                                           (5%)
  • How can this particular phrase be successfully transmitted even when visual and aural cues are impeded?                                                                     (10%)


Question 2                                                                                (c. 400 words) (20%)




  1. Describe and illustrate the physiological mechanisms involved in normal voicing, with examples. What are the acoustic consequences of these mechanisms for nasals in spectrographic analyses?


  1. Describe and illustrate how duration is used as an identifying acoustic cue in two different scenarios: both for fricatives, and for V + C clusters.



  1. What are the acoustic correlates of pitch and how is it produced? Discuss its prosodic function.




Further notes on plosives

Combinations of plosives eg talk to - in fluent speech we omit the burst for the first plosive and the silence for the second [tɑ:k˺thu:].

Plosives combine easily with other consonants to form consonant clusters, as in the initial clusters in the following words:

  • /s/ + plosive -- spout, stout, Scout.
  • plosive + /w/ -- tweezer, quorum, square.
  • plosive + /j/ -- pew, cue, skew.
  • [/s/] + plosive + /l/ -- play, splay, clay, sclerosis.
  • [/s/] + plosive + /r/ -- pray, spray, tray, stray, Cray, scrape.

In cases with a preceding /s/, the plosive will be unaspirated. In the aspirated allophones, the aspiration will be used to begin the sketch of the following glide or liquid formants rather than moving toward those of the succeeding vowel and is marked as devoiced eg [spr̥eɪ].

When a plosive is followed immediately by a fricative, particularly /s/ or /z/, the burst will tend to merge into the frication and thus will not be easily recognizable. Example words are very common in English, since /s/ or /z/ is the mark of the plural.

The first stop of a cluster has no audible release, as in apt [ˈæp˺t], doctor [ˈdɒk˺tə]; such sounds are frequently described as "unreleased", although the two consonants overlap so that the release of the first takes place during the hold of the second, masking the first consonant's release and making it inaudible. This can lead to cross-articulations that seem very much like deletions or assimilation, eg. hundred pounds [hʌndɹɛb pʰaunz] but weakened contacts may still be made, so that the /d/ does not entirely assimilate a labial place of articulation, but rather co-occurs with it.

The term 'unreleased' is also used for a stop before a homorganic nasal eg  catnip. In such cases, however, the stop is released as a nasal and is more precisely transcribed [ˈkhætⁿnɪp].


Phonetic features

  • place of articulation: /p, b/=bilabial, /t, k/=alveolar, /k, g/=velar
  • force of articulation: /p, t, k/=fortis (strong), /b, d, g/=lenis (weak)
  • aspiration:
    • when /p, t, k/ in initial position in accented syllable, /p, t, k/ aspirated
    • when /p, t, k/ precede silence, no audible release, may be some aspiration
    • when any plosive follows /s/ within the same syllable, the distinction between /p, t, k/ and /b, d, g/ is neutralized
  • voicing:
    • /b, d, g/ are fully voiced in between voiced sounds
    • when /b, d, g/ in initial position, vocal fold vibration begins in the last portion of the compression stage
    • when /b, d, g/ in final position, vocal fold vibration finishes in the first part of the compression stage
  • length of preceding sounds:
    • when syllables are closed by a voiceless plosive (or any voiceless consonant), they are shorter than those, which are open or closed by a voiced consonant



  • the closing stage: articulating organs move together in order to form an obstruction
  • the compression stage: lungs compress the air behind the closure (may or may not be voiced)
  • the release stage: the organs forming the obstruction part rapidly allowing the compressed air to escape abruptly (if voiced, the vocal-fold vibration continues throughout this stage)
  • no audible release in final positions: closure stage maintained, the air compression weakening, release achieved by a gentle, delayed, inaudible opening with the lowering of the soft palate and separation of organs which are forming the oral closure (final /p, t, k/ distinguished from /b, d, g/ by reducing the length of the sound preceding /p, t, k/)
  • no audible release in stop clusters: when a plosive is followed by another plosive or an affricate: the first sound has no audible release and closure of the second is made before the release of the first (one closing and releasing stage for both)
  • glottal reinforcement of final /p, t, k/: the oral closure is reinforced by a glottal closure (glottal closure either coincides with the oral one or even replaces it)
  • nasal release: when a plosive is followed by the nasal consonant, the release of air is effected by the escape of compressed air through the nasal passage (/p, b/+/m/, /t, d/+/n/, /k, g/+/η/)
  • lateral release: when /t, d/ is followed by /l/, /t, d/ is released laterally
  • affrication of plosives: some plosives (/t, d/) are sometimes made with a slow, fricative release


Note that what we call voiced plosives /b d g/ are:

  • Partially devoiced in initial position
  • Voiced between voiced sounds
  • Fully devoiced in final position
  • Have no audible release when followed by another plosive
  • Have a nasal release when followed by a nasal



  • The sentence comprises the following (in no particular order):
    • A period of time
    • A colour
    • A type of bird
    • An action
    • A month
    • A large amount


  • Go through the spectrograms systematically, highlighting acoustic evidence for:
    • Fricatives – how do they compare in terms of duration, diffusion, frequency location? Is there a voice bar? Compare all words except 8 and 9
    • Plosives – can you see VOT for any of them in onset position? Is a voice bar apparent? Compare words 1, 3, 4, 5 and 7 in particular.
    • Vowels – compare F1 and F2 – how different are they in words 1 and 2 and words 8 and 9? How similar are they in words 5 and 6? Where is the diphthong?
    • Are there any approximants? How can you tell?
    • There are a few alveolar nasals – can you see their formant patterns and their effects on adjacent vowels? Look at words 1, 8 and 9 in particular.


  • Think about syllable structure; there is only one word of two syllables, and the rest generally comprise a CVC structure, so make sure you examine onsets and codas.


  • Write down all the potential sounds for each of the features – that way you should start to see what is possible and what is not possible lexically.