Presentation on theme: "Assessing Speech Intelligibility and Severity"— Presentation transcript:
1 Assessing Speech Intelligibility and Severity What are some standard procedures?
2 Are measures of intelligibility and severity the same? Although judgements about intelligibility and severity may be correlated, they represent two different indices about an individual’s speechFor example, a child may have a severe resonance disorder, but his/her speech is still intelligible
3 Intelligibility Scales Typically a panel of 2-5 listeners (expert ~ novice; familiar ~ unfamiliar) rate a taped (audio or video) segment of child’s speechRank intelligibility of child’s speech compared to age peersScales typically use 3-point or point judgment scales (See Bleile)scores are averaged to derive a composite intelligibility rating score
4 Intelligibility Scales Kent, Miolo, & Bloedel (1994) compared 19 intelligibility measures according to 5 categories that differed with regard to the emphasis of the analysis (phonetic ~ phonemic; word level ~ conversation)
5 Intelligibility Scales Listed 8 factors that influence clinical evaluation of intelligibility:loss of phonological contrastsloss of contrasts in specific environmentsextent of homonymyamt of difference between target~realizationfrequency of occurrence in Englishconsistencyfamiliarity of listener with speakercontext in which communication occurs
6 IntelligibilityWeston & Shriberg (1992) concluded that articulation variables alone cannot account for all the breakdowns that result in communicationother general contextual and linguistic variables are related to speech intelligibility
7 SeveritySimilar to intelligibility rating scales, a panel of familiar or unfamiliar listeners judge a segment of a child’s recorded (audio or video-taped) speech (single word or connected speech)
8 Severity Perceptual scales (see Bleile) or quantitative measures 4 Point Clinical Judgement Scale of SeverityNo disorder-Mild-Moderate-Severeaverage score of 3.5 often required to provide clinical services
10 Comparison of PCC and PDS Severity Ratings Mild >90%Mild-Mod 65-85%Mod-Sev 50-65%Severe <50%PDSMild ptsModerate 20-39Severe 40-59Profound 60+
11 Shriberg, Austin, Lewis, McSweeny, & Wilson (1997) 9 speech metricsPCC (based on conv speech)PCC-A (common clinical distortions scored correct)PCC-R ([un]common distortion scored correct)ACI (differentially weighs distortion ~ sub/omis)PCI (percentage of sounds mastered-early talkers)PVC (similar to PCC, but for vowels/diphthongs)PVC-R (similar to PCC-R, but for vowels/diphthongs)PPC (percentage to consonants/vowels correct)PPC-R (scores distortions correct)
12 Which metric is most appropriate? Depends on specific needs of the assessmentInterest limited to consonantsPCC, PCC-A, PCC-R, ACIYoung/severely delayed childrenPCIInterest in vowels/diphthongsPVC, PVC-RInterest in articulation competence on all speech soundsPPC, PPC-R
13 Rafaat, Rvachew, & Russell (1995) Purpose of study was to determine the percentage of agreement between SLPs in rating PI severityAdequate reliability for older children (4;6+), but unreliable for children under 3;6Unable to reliably distinguish TD from mild delay
14 Why were SLPs less reliable on severity ratings of younger children?
15 What factors account for differences in reliability ratings?