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Thresholds, Recognition Tests, MCL &UCL

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1 Thresholds, Recognition Tests, MCL &UCL
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: Adaptive Instruct 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.

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:

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


28 Rollover Indices for the preceding examples
Normal: ( ) / 100 = 0.0 Rollover: ( ) / 44 = 0.54 Cochlear: ( )/80 = 0.125 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 BCNTE Use Pink (Speech) Noise, or white noise Suggested Levels: EM = PBHL TE – IA + ABGNTE + 20 dB PB Test Level Masker Level 40 dB HL --- 60 dB HL 40 dB EM 80 dB HL 60 dB EM

30 Reliability of Word Recognition Scores
Range of possible scores upon retest Thornton & Raffin (1978) # of Items Initial Score 100 50 25 10 90 81-96 76-98 72-100 50-100 37-63 32-68 28-76 10-90 20 11-32 8-36 4-44 0-60


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

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

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

36 95% Confidence Limits for Word Recognition Score
SPRINT: Speech Recognition Interpretation Chart 95% Confidence Limits for Word Recognition Score PTA (dB HL) 2nd % Score 1st % Correct Score © by Linda M. Thibodeau, 1999

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

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