2 Testing with Recorded Speech 1000 Hz Calibration tone provided on recordingBalance calibration tone on VU meter at 0
3 Live Voice Testing: Controlled Vocal Effort, Adjust microphone sensitivityto 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 monosyllablese.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 LevelBegin Descending procedureThresh = Start Level - # C + Corr. FactorAdaptiveInstructFamiliarizeBracket (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 PTAIn 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 NOISESTARTING LEVEL=SRTTE –35 +ABGNTE
11 Long Term Spectrum of Speech And the variance around it.
12 Bone Conduction SRT's:useful in childrenuseful in malingerers.
13 Masking for SRT If SRT - IA > best BC Thresh NTE Put in at least: STARTING LEVEL=SRTTE –35 +ABGNTEBut no more than:OVERMASK = EMNTE-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 – SRTNormally 100 dB or greaterUnchanged in conductive lossesCan 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 ListsFour 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 ListsGardner’s Hi Frequency Word ListsCalifornia Consonant TestNonsense Syllable ListsThe Nonsense Syllable Test (NST)Sentence TestsThe Synthetic Sentence Identification (SSI) testSpeech Perception in Noise (SPIN) testConnected Speech Test (CST)The Hearing In Noise Test (HINT)
21 Children’s TestsWord Intelligibility by Picture Identification (WIPI) test – six pictures to choose from.Northwestern University Children’s Perception of Speech (NUCHIPS) test – four pictures to choose fromMonosyllable-Spondee-Trochee test – distinguishing word shapes, not identifying particular words; used in cochlear implant cases.
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 noiseMeasure has low varianceNot 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 thenEither remains high (normal), orDrops at higher levels (Rollover)Rollover Index = (PBmax – Pbmin)/PBmax
28 Rollover Indices for the preceding examples Normal: ( ) / 100 = 0.0Rollover: ( ) / 44 = 0.54Cochlear: ( )/80 = 0.125Rollover 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 BCNTEUse Pink (Speech) Noise, or white noiseSuggested Levels:EM = PBHL TE – IA + ABGNTE + 20 dBPB Test LevelMasker Level40 dB HL---60 dB HL40 dB EM80 dB HL60 dB EM
30 Reliability of Word Recognition Scores Range of possible scores upon retestThornton & Raffin (1978)# of ItemsInitial Score1005025109081-9676-9872-10050-10037-6332-6828-7610-902011-328-364-440-60