Testing with Recorded Speech 1000 Hz Calibration tone provided on recording Balance calibration tone on VU meter at 0
Live Voice Testing: Controlled Vocal Effort, Adjust microphone sensitivity to have the speech balanced at 0 dB on VU meter
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.
SRT Stimuli: Spondees 2-syllable words with equal stress can be divided into two monosyllables e.g., hotdog, baseball, whitewash, mousetrap, birthday, eardrum...
Why spondees? because their intelligibility curves rise from near chance to 100% performance within a few decibels. This provides a much more accurate threshold.
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.
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.
Exception for steeply-sloped high frequency losses. SRT will be better than PTA In this case use Fletcher average: 500 Hz Hz / 2.
Masking for SRT's: IF SRT - IA > best BC THRESH in NTE. WHITE or PINK NOISE STARTING LEVEL=SRT TE –35 +ABG NTE
Long Term Spectrum of Speech And the variance around it.
Bone Conduction SRT's: useful in children useful in malingerers.
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
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
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.
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
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.]
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.
CNC Word Lists Consonant-Nucleus-Consonant words Phonemically balanced Four 50-item lists: the NU-6 Word Lists
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)
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.
WIPI Sample Item
NU-CHIPS Sample Item
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
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)
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
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.
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
Reliability of Word Recognition Scores Range of possible scores upon retest Thornton & Raffin (1978) # of Items Initial Score
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
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
Expected PB max by Hearing Loss Dubno, J. et al. JSHR 1995
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.
( Mueller & Killion) Counting Dots: ( Mueller & Killion) Each dot = 1% # of dots below HL line on audiogram = % correct identification for speech.