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Speech Audiometry Thresholds, Recognition Tests, MCL &UCL.

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Presentation on theme: "Speech Audiometry Thresholds, Recognition Tests, MCL &UCL."— Presentation transcript:

1 Speech Audiometry Thresholds, Recognition Tests, MCL &UCL

2 Testing with Recorded Speech  1000 Hz Calibration tone provided on recording  Balance calibration tone on VU meter at 0

3 Live Voice Testing:  Controlled Vocal Effort,  Adjust microphone sensitivity  to have the speech balanced at 0 dB on VU meter

4 Thresholds for Speech:  Speech Detection Threshold: lowest level at which the listener can tell that something is there (when the signal happens to be speech).  Speech Recognition Threshold: lowest level at which the listener can actual identify what the speech stimulus is.

5 SRT Stimuli: Spondees  2-syllable words with equal stress  can be divided into two monosyllables  e.g., hotdog, baseball, whitewash, mousetrap, birthday, eardrum...

6 Why spondees?  because their intelligibility curves rise from near chance to 100% performance within a few decibels.  This provides a much more accurate threshold.

7 SRT Methods ASHA:  Instruct  Familiarize (16 words)  Find Starting Level  Begin Descending procedure  Thresh = Start Level - # C + Corr. Factor Adaptive  Instruct  Familiarize  Bracket (2-4 wds/level)  Thresh = lowest level where you get at least 50% correctly repeated.

8 The SRT should agree with the PTA  (-8 to +6 dB of best threshold at these frequencies).  This way we have a double-check on results.

9 Exception for steeply-sloped high frequency losses.  SRT will be better than PTA  In this case use Fletcher average: 500 Hz Hz / 2.

10 Masking for SRT's:  IF SRT - IA > best BC THRESH in NTE.  WHITE or PINK NOISE  STARTING LEVEL=SRT TE –35 +ABG NTE

11 Long Term Spectrum of Speech And the variance around it.

12 Bone Conduction SRT's:  useful in children  useful in malingerers.

13 Masking for SRT  If SRT - IA > best BC Thresh NTE  Put in at least: STARTING LEVEL=SRT TE –35 +ABG NTE But no more than: OVERMASK = EM NTE -IA> Best BC Thresh TE

14 Most Comfortable Loudness Level  Instructions important: you can strongly influence how a person responds.  "I am going to continue talking to you as I make my voice louder and softer. I will keep asking you to tell me whether my voice is too soft, too loud or comfortably loud."  Do a number of sweeps in level.  normally between 40 and 55 dB above SRT

15 Uncomfortable Loudness Level  Begin at MCL, raise level as you continue to talk.  "I am now going to ask you to tell me how my voice sounds to you as I make it louder. Please tell me if the level is comfortable, a little loud, or uncomfortably loud.”  Uncomfortable = loud enough so you would not want to listen to my voice for a long time.

16 Range of Comfortable Loudness  (Or the Dynamic Range for Speech)  = UCL – SRT  Normally 100 dB or greater  Unchanged in conductive losses  Can be much smaller in sensorineural hearing loss

17 Word Recognition Testing  Open set-client can respond with any word he/she can think of.  Closed set-response options are provided for the client (multiple choice test).  Free response-client is free to respond or not.  Forced Response-client must say something.   [Forced choice = closed set forced response.]

18 Phonetically Balanced Word Lists  selection of a group of words so that each phoneme appears with the same frequency it has in the normal lexicon. Based on Thorndike-Lorge lists of words and word frequencies.  So-called PB word lists-- CID W-22 Lists  Four lists of 50 words each.

19 CNC Word Lists  Consonant-Nucleus-Consonant words  Phonemically balanced  Four 50-item lists: the NU-6 Word Lists

20 Alternative Speech Choices  High Frequency Word Lists Gardner’s Hi Frequency Word Lists California Consonant Test  Nonsense Syllable Lists The Nonsense Syllable Test (NST)  Sentence Tests The Synthetic Sentence Identification (SSI) test Speech Perception in Noise (SPIN) test Connected Speech Test (CST) The Hearing In Noise Test (HINT)

21 Children’s Tests  Word Intelligibility by Picture Identification (WIPI) test – six pictures to choose from.  Northwestern University Children’s Perception of Speech (NUCHIPS) test – four pictures to choose from  Monosyllable-Spondee-Trochee test – distinguishing word shapes, not identifying particular words; used in cochlear implant cases.

22 WIPI Sample Item

23 NU-CHIPS Sample Item

24 Administration: once you've chosen materials  transducer: AC, BC, or sound field.  level: at some SL (40)--may be specified by test.  response: repeat, write, or mark on list.  competing noise: what, how loud.  masking: calculate (Test Level - IA) - BC nte

25 Adaptive Testing  Finding a threshold, not a % score  Typically in presence of competing noise  Measure has low variance  Not yet common in clinical practice (although we will talk about the HINT soon)

26 Performance-Intensity Functions  PI function: word recognition scores obtained at a range of stimulus levels.  Curve reaches a peak (Pbmax), and then  Either remains high (normal), or  Drops at higher levels (Rollover)  Rollover Index = (PBmax – Pbmin)/PBmax

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28 Rollover Indices for the preceding examples  Normal: ( ) / 100 = 0.0  Rollover: ( ) / 44 = 0.54  Cochlear: ( )/80 =  Rollover Indices of 0.45 or greater indicate a neural (VIIIth nerve) problem.

29 Cross Hearing & the Need to Mask  If Word level (HL) TE – IA > Best BC NTE  Use Pink (Speech) Noise, or white noise  Suggested Levels: EM = PBHL TE – IA + ABG NTE + 20 dB PB Test LevelMasker Level 40 dB HL dB HL40 dB EM 80 dB HL60 dB EM

30 Reliability of Word Recognition Scores  Range of possible scores upon retest Thornton & Raffin (1978) # of Items Initial Score

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32 NU-6 Words Ordered by Difficulty  Present 10 words- stop if 0 or 1 error  If >1 error, present next 15 words  If < 3 errors (out of 25), stop  If > 3 errors administer all 50 words Hurley & Sells, 2003

33 Interpreting Word Recognition Scores Score: General Word Recognition Ability: 90 to 100Within Normal Limits 75 to 90Slight Difficulty 60 to 75Moderate Difficulty 50 to 60Poor < 50Very poor

34 Expected PB max by Hearing Loss Dubno, J. et al. JSHR 1995

35 PTA (dB HL) 2 nd % Score 1 st % Correct Score SPRINT: Speech Recognition Interpretation Chart © by Linda M. Thibodeau, 1999 Abnormally Low Word Recognition for HL

36 PTA (dB HL) 2 nd % Score 1 st % Correct Score SPRINT: Speech Recognition Interpretation Chart © by Linda M. Thibodeau, % Confidence Limits for Word Recognition Score

37 Predicting WRS from the audiogram: The AI  The Articulation Index  Audibility Index  “Count the dot” audiogram  If word recognition is poorer than prediction: neural hearing loss or central disorder.

38 ( Mueller & Killion) Counting Dots: ( Mueller & Killion)  Each dot = 1%  # of dots below HL line on audiogram = % correct identification for speech.


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