Speech Audiometry

1. Speech Audiometry SPA 4302 Summer A, 2004

2. The Diagnostic Audiometer Equipped with • Inputs for microphones, cassette tapes, or CDs • Volume unit (VU) meters • Circuit for masking noise or mixing noise with speech in the same ear • Ability to test monaurally or binaurally • Intensity levels ranging from -10 to 110 dB HL • Outputs for auxilliary amplifiers (to speakers) • Talkback system to allow patient/clinician communication from different rooms/booths

3. The Patient’s Role in Speech Audiometry • Pt must know and be able to respond to word in the language of the test. • Responses: • Verbal repetition • Writing or marking response • Picture pointing • Clicking on choice on computer

4. The Clinician’s Role in Speech Audiometry • Must be able to convey to pt their task, • Keep face from pt’s view • Understand pt responses

5. Speech-Threshold Testing • Speech Detection Threshold: lowest level at which the listener can tell that something is there (when the signal happens to be speech). Also called the speech awareness threshold. • Speech Recognition Threshold: lowest level at which the listener can actual identify what the speech stimulus is. Also called the Spondee threshold.

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

7. Why spondees? • because their intelligibility curves rise from near chance to 100% performance within a few decibels. (see curve 1 in figure 5.1) • This provides a much more accurate threshold.

8. Descending Approach Start approx 10 dB above expected threshold Drop in 5 dB steps 5 words per level Stop when pt misses 5 out of last 6 words Threshold = start level – number correct + correction factor Adaptive Approach Like Pure Tone procedure down in 10 dB steps, up in 5 dB steps Up to 4 words per level Threshold = lowest level at which pt correctly id’s at least 2 words (>50%). SRT Methods

9. Masking for SRT • If SRT - IA > best BC Thresh NTE • Put in at least: STARTING LEVEL=SRTTE –35 +ABGNTE But no more than: OVERMASK = EMNTE-IA> Best BC Thresh TE

10. 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

11. 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.

12. 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

13. 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.]

14. 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.

15. CNC Word Lists • Consonant-Nucleus-Consonant words • Phonemically balanced • Four 50-item lists: the NU-6 Word Lists

16. 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)

17. 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.

18. 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

19. Rollover Indices for the preceding examples • Normal: (100 - 100) / 100 = 0.0 • Rollover: (44 - 20) / 44 = 0.54 • Rollover Indices of 0.45 or greater indicate a neural (VIIIth nerve) problem.

20. Cross Hearing & the Need to Mask • If Word level (HL)TE – IA > Best BCNTE • Use Pink (Speech) Noise, or white noise • EM = PBHL TE – IA + ABGNTE

21. Interpreting Word Recognition Scores

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