Table 3

Examples of language, speech, voice and prosody changes suggesting classification as functional or structural disease aetiology (link to annotated recordings)

Speech subsystemsSpeech features if present supporting a functional aetiologyFeatures if present supporting a structural disease aetiology
Language (morphology, syntax, semantics)Apparent difficulty with simple grammatical structure but no problems on more complex sentences
Idiosyncratic expressions: ‘very overfilling with water’, ‘stool that is getting ready to tip over’, ‘thinking in thoughts’.
Isolated and/or inconsistent omission of—ing endings from verbs,
Inappropriate addition of/s/sound to words (eg, thankyous, byes, fall overs) but not to all words; no apparent articulatory cause for this.
Semantic paraphasic slips, for example, ‘kitchen cupboard’ labelled ‘china cabinet’, ‘arch’ read as ‘arc’.
Difficulty marking past tense syntactically while present and future tense relatively spared.
Voice qualityExcessive and/ or inconsistent variability in, for example, degree of hoarseness or breathiness; changes not associated with structural neurological changes to phonation, for example, falsetto
voice quality and pitch inconsistent with age and gender of speaker.
Consistent voice changes (eg, creaky voice) compatible with alterations to tone, power, coordination of laryngeal muscles.
ArticulationIncompatibility of vowel versus consonant pronunciation: for example, tendency to produce vowels at back of mouth, but production of consonants suggests this is not due to neuromuscular (eg, tongue tip weakness, velar insufficiency) difficulties
Isolated change of /r/ sound to uvular ‘r’ sound, for example, associated with a French accent, in presence of no other related changes
Inconsistent consonant production, for example, ‘cookie jar’ produced as ‘tutty dar’ but ‘j’, /k/, /g/, ‘sh’ produced effortlessly and accurately in other words.
Changes to articulation compatible with structural neurological motor speech disorder, for example, articulatorily more complex sounds/ sound sequences more susceptible to distortion than less complex sounds ‘pikssure’ for ‘picture’
Changes to vowel production compatible with weakness of tip or back (or both) of tongue.
Perceived accentMarked variability within short passage (completely unaccented to heavily accented; ‘Italian’ to ‘Australian’)
‘Accent’ does not match accents found in natural languages, or shows affective variation, for example, childish rather than ‘foreign’ tone of voice.
Perceived accent in keeping with consistent alteration to specific aspects of articulation or prosody (eg, producing /w/ as /v/, effects of hypernasality on vowels, insertion of ‘uh’ in consonant clusters—‘suhtanding, pikuhture’ for ‘stand, picture’).
Prosody (rate, word and sentence stress, intonation)Excessive and inconsistent swings in pitch and intonation and/or where stress placed on word, for example, ‘thuuu cooKIE juh’ instead of ‘the COOkie jar’.Changes compatible with recognised structural neurological diagnoses, for example, scanning speech of cerebellar ataxia, syllabification of apraxia of speech, monopitch and monoloudness of Parkinson’s disease.
Fluency (pauses, blocks, repetitions)‘Pseudo-struggle’ for example, output has effortful quality but other aspects, such as rate of speech and articulatory accuracy appear intact
Pauses occur in syntactically inappropriate places and/or within words without any apparent articulatory/respiratory reason for this
Idiosyncratic inconsistent splitting up of words, for example, pri-sm, div-i-zhu-n.
Changes to pauses consistent and compatible with changes to, for example, respiration, speech-motor planning
Pauses occur at syntactically and phonologically lawful loci
Struggle/effortfulness of speech consistent and compatible with changes to tone, power, coordination and manifest in concurrent other aspects of speech and voice.