Presentation on theme: "Assessing Speech Intelligibility and Severity"— Presentation transcript:
1Assessing Speech Intelligibility and Severity What are some standard procedures?
2Are 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
3Intelligibility 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
4Intelligibility 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)
5Intelligibility 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
6IntelligibilityWeston & 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
7SeveritySimilar 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)
8Severity 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
10Comparison 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+
11Shriberg, 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)
12Which 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
13Rafaat, 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
14Why were SLPs less reliable on severity ratings of younger children?
15What factors account for differences in reliability ratings?