IPA Extensions (extIPA)

In the US, speech disorders affect 5% of primary school children and 11.5% of the population. The complex speech process is achieved with precision timing and muscle and nerve control. The function can be thrown off balance by various issues such as a stroke, congenital disability, or an accident. The resultant speech and language disorders can affect learning, social relationships, and other developmental issues. Lisps, stuttering, and inability to speak are a few of the possible communication disorders that can occur. 

How is the extIPA Used?

Speech-language therapists (SLTs) and pathologists transcribe disordered speech for diagnosis and intervention. Clients often use sounds not found on the IPA chart or sometimes atypical sounds not found in any language. The extIPA has a variety of symbols needed for clinical transcription to show if the cause of the disorder is associated with developmental, congenital, or acquired conditions. Diagnosing a disorder correctly depends on the accuracy of the interpretation and evidence-based decision-making.

How the extIPA Was Developed

To transcribe disordered speech accurately, the IPA drew up an initial set of characters and diacritics and presented them at the Kiel Convention in 1989. IPA extensions, abbreviated extIPA, were issued in 1990, and over the next few years, they were modified and officially published in the IPA’s Journal of the International Phonetic Association in 1994. At that time, it was also adopted by the scholarly association International Clinical Phonetics and Linguistics Association (ICPLA). They are dedicated to studying language and speech disorders and publish a monthly journal, Clinical Linguistics and Phonetics.

Also referred to as the Extended IPA, linguists use them to designate several sounds in standard communication. The sounds include smacking lips, gnashing teeth, hushing, and other lexical speech that does not have an IPA symbol, such as lateral fricatives. There are several nondescript extensions not included on the extIPA, including:

• Doubled Symbols to Maximize a Feature
  • Strongly Aspirated
  • Extra Stress
  • Extra-Rhotic
• Superscript to Minimize a Feature
  • Slightly Prenasalized
  • Epenthetic Schwa
  • Slightly Affected 

Diacritics in Disordered Speech

The use of diacritics to indicate sounds found in disordered speech is increasing, as well as the number of dedicated letters to transcribe the speech of those with cleft palates or lisps. Standard diacritics are repeated to denote features that are common in disordered speech. Some of these include:

• Preaspiration
• Linguolabial
• Laminal Fricatives
• Velopharyngeals
• Nasal Fricatives
• Percussive Consonants
• An asterisk ⟨*⟩ for a sound segment with no symbol 

For example, the transcription ⟨ɹ̈⟩ is used for an English molar-r, as opposed to ⟨ɹ̺⟩ for an apical r. Some articulations are indiscernible and rarely identified in non-disordered speech. Some sounds found in languages worldwide don’t have a symbol in the basic IPA, and so the extIPA continues to evolve. 

Additional Transcription Modifications

Some standard IPA symbols were broadened for use by the extIPA, and others were added. One adaption is the use of parentheses around phonation diacritics to indicate partial speech sound. Single parenthesis on the right or left of the voicing means it is partially spoken at the end or beginning of the segment. Parentheses can demonstrate silent articulation or mouthing, as in the sign to hush or silent pauses, for example (…).

Partially voiced sounds can be indicated using different arrangements of the parentheses to implicate atypical voicing or partial devoicing, as in pathological speech. Changing the position of the diacritics around letters can be used the same way. The IPA has a long-understood rule that letters can be used in superscript form for similar reasons. It can indicate another letter’s release, onset, or flavor, specifically for the fricative release of plosives. 

Prosodic Notation and Indiscriminate Sounds

In addition to the parentheses, bracket notation is used to gather as much detail as possible. Covering noises such as a ⸨knock⸩ or a ⸨cough⸩ are also noted to show responses in context for better understanding. 

In 2015 the extIPA was revised and expanded, and new symbols were added to Unicode in 2020. Voice Quality Symbols (VoQS) are another set of phonetic symbols used for disordered speech transcription to indicate voice quality. This set of symbols describes voice quality (VoQS), such as whispering. As with prosody notation in the extended IPA, VoQS symbols are typically combined with curly braces on either end of a speech section. 

The extIPA places circles on some indistinguishable or unidentifiable sounds rather than inserting single parentheses like the IPA. All capital letters can serve as wild cards for certain sounds when combined with extIPA and IPA diacritics. 

Speech pathologists also often use superscripts to indicate that a target sound is incompletely articulated. Because the meaning of superscripting in the IPA can be ambiguous, it is not supported by the International Clinical Phonetics and Linguistics Association (ICPLA). Instead, a transcription would place a mark on the specific consonant that is silent or weakened.