1Speech Audiometry

Dynamics of speech

Intensity Whisper - 20 dB HL Normal conversational speech - 50 to 60 dB Loud speech - 70 dB Shouting - 90 dB

2What is speech audiometry? Refers to the assessment of a clients hearing using speech

stimuli. A clients performance on speech audiometric tasks, especially

those that are suprathreshold, can provide an audiologist with amore accurate view of the clients communication performance inthe real world.

Materials Nonsense syllables Monosyllabic words Spondaic words Sentence tests

Contribution of Speech Audiometry

To determine the extent of speech-recognition difficulty. To provide a cross-check to ensure reliable data. It can be sensitive to auditory problems that pure tone

testing might miss (sensitivity) To aid in diagnosis of retro-cochlear problems.

Assists in the selection of amplification systems. Helps clinician educate patients about loss and make a

prognosis about treatment outcomes.

3Test environment

Normally sound treated booth Pt should not see the examiners face to avoid lip reading cues.

Setup Input selection: to select the

desired source of speech material tape, CD player for recorded

speech microphone for live voice

Input level control: used with theVU (volume unit) meter toensure that the speech signal areof at the level necessary for themto being properly calibrated

Attenuation: to control the levelof speech being presented to thepatient.

Output selector: through whichmode you want to present thespeech signal to the patient

4Live Voice Testing:

Controlled Vocal Effort. Adjust microphone sensitivity

To have the speech balanced at 0 dB onVU meter. However, it is recommend to use CDs whenever possible.

VU

Presentation of Speech Tests

Monaural (one ear at a time, usualmethod).

Binaural (both earssimultaneously).

Can be presented with earphones. Can be presented via bone

conduction. Can be presented in the sound field

using speakers.

Monitored live-voice (MLV) Pre-recorded lists on CD or cassette. Lists of words that patient repeats. Standardized picture tests that require

the patient to point to a picture thatmatches the spoken word

Standardized speech-in-noise tests.

5Speech audiometry tests

Speech Recognition Thresholds Speech DetectionThresholds Word Recognition Testing

Level of auditory ability assessed

Awareness: tests that require the patients to simply indicatethat a sounds was detected.

Discrimination: tests that require the patient to detect achange in the acoustic stimulus.

Identification/recognition: tests that require the patient toattach a label to the stimulus either by pointing to acorresponding picture or object or repeating the stimulusorally: Speech recognition threshold (SRT) Word recognition scores or sentence recognition scores.

6Speech Recognition Thresholds Abbreviated as SRT Defined as

The minimum hearing level for speech at which an individualcan recognize 50% of the speech material (ASHA, 1988).

Uses spondees as speech material

7SRT relation to pure tone audiogram

Clinically, PTA should be within 10 dB of the SRT. SRTs can be predicted by finding the average of 500, 1000,

and 2000 Hz (Pure tone average, PTA). In some cases, SRT may be higher (worse) than the three

frequency PTA. Age, or disorders of the CANS.

In other cases, the SRT may be much lower (better) than thePTA. When the audiogram falls precipitously in the high frequencies.

Use of the SRT as anaverage hearing levelcan be problematicbecause it is possiblefor a clients SRT toreflect only one of thethree frequencies oftenassociated with it.

8Test administration Instruction:

I am going to review a series of words with you. Please repeateach word that you hear.After this review, I will begin topresent these words at softer and softer levels. Please continueto repeat the words that you hear, even if they are quite soft andeven if you have to guess

Familiarization: This is an important part of test administration and allows

audiologists to omit words that may not be familiar to theclient. ASHA guideline strongly suggests that familiarization not be eliminated

from the test protocol.

9Test administration.procedure

Although ASHA (1988) guidelines suggest use of a descendingapproach to obtaining the SRT, various approaches (e.g.,ascending, descending, or ascending/descending) can yieldvery similar results when testing in 5-dB steps. The basic idea ofall of these approaches is to present a series of spondee words severaltimes, until 50 percent understanding is achieved at one level.

ASHA recommended procedure Determination of threshold

Step one: determine initial starting level: Present one spondaic word at a level 30 to 40 dB HL above the anticipated SRT. If a

correct response is received, drop the level in 10-dB steps until an incorrect responseoccurs. Once an incorrect response is received, present a second spondaic word atthe same level. If the second word is repeated correctly, drop down by 10-dB stepsuntil two words are missed at the same level. Once you reach the level where twospondees are missed, increase the level by 10 dB.This is your starting level.

Step two:Threshold estimation Present five spondaic words at the starting level. An individual should get the first

five spondaic words correct at the starting level, if not increase starting level by 10.Drop the level by 5 dB, and present five spondaic words. Continue dropping the levelby 5 dB until the individual misses all five spondaic words at the same level; testis then terminated.

Calculate threshold as:Starting level - # of correct responses + 2 dB (correction factor)

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Speech Detection Thresholds

The SDT is not commonly part of routine audiological assessment,probably because it provides less information than other speechmeasures.

ASHA guidelines suggest that the methods used for pure tone thresholdtesting be applied to SDT testing.

Speech material: Stimuli for SDT testing are not standardized.According to ASHA, the exact

stimulus used is not critical because the SDT measures detection and notrecognition.

For purposes of consistency, use of bup-bup-bup or uh-oh is suggested. Use of the child or clients name should be avoided because it will result in a highly

variable stimulus. Other possible speech materials include speech babble, running speech, or familiar

words. Regardless of the type of stimuli used, it is important to record the material type on

the audiogram for reporting and comparison purposes.

Word Recognition Testing Word recognition testing may be defined as a measure of

speech audiometry that assesses a clients ability to identifyone-syllable words that are presented at hearing levels thatare above threshold to arrive at a word recognition score.

How is it different than SRT? Uses monosyllabic words (words of one-syllable), not spondees.

These words are phonetically balanced. Word recognition is performed at a suprathreshold level.

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Method for Obtaining SRS

Decide method of delivery (MLV, recorded). Choose materials to be used (word lists etc). Inform patient with regards to method of response. Select intensity. Decide if multiple levels should be tested. Decide if test will be presented with noise in the background.

Word Recognition Testing

Open set : pt can respond with any word he/she can think of. Closed set: response options are provided for the pt

(multiple choice test). Free response-client is free to respond or not. Forced Response-client must say something.

[Forced choice = closed set forced response.]

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Word recognition scores

Quantifies pts ability to discriminate speech: It determines the extent of speech-recognition difficulty. It aids in diagnosis of the site of the disorder in the auditory

system. It assists in the determination of the need for and proper selection

of amplification systems. It helps the clinician to make a prognosis for the outcome of the

treatment efforts. Hearing aid fitting.

Contribution of speech evaluation to differentialdiagnosis

Discrepancy in performance between scores from a patientstwo ears or between word and sentence recognition.

Rollover effect: Reduction in speech recognition (more than20% from maximum performance) with increases inintensity. Occurs with retrocochlear pathological conditions

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Performance-Intensity Functions

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 - 100) / 100 = 0.0

Rollover: (44 - 20) / 44 = 0.54

Cochlear: (80 - 70)/80 = 0.125

Rollover Indices of 0.45 or greater indicate a neural (VIIIthnerve) problem.

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The use of PI functions is a way of sensitizing speech bychallenging the auditory system at high-intensity levels.Because of its ease of administration, many audiologists use itroutinely as a screening measure for retrocochlear disorders.The most efficacious clinical strategy is to present a word listat the highest intensity level (usually 80 dB HL). If the patientscores 80%, then potential rollover of the function isminimal, and testing can be terminated. If the patient scoresbelow 80%, then rollover could occur, and the function iscompleted by testing at lower intensity levels.

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Test-specific:each test muchhave its valuesto determinemax wordrecognition

Predicting Speech Recognition Word-recognition ability is predictable from the audiogram

in most patients.This has been known for many years.Essentially, speech recognition can be predicted based on theamount of speech signal that is audible to a patient.Theoriginal calculations for making this prediction resulted inwhat was referred to as an articulation index, a numberbetween 0 and 1.0 that described the proportion of theaverage speech signal that would be audible to a patient basedon his or her audiogram (French & Steinberg, 1947).

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Predicting WRS from the audiogram: The AI

The Articulation Index Audibility Index Count the dot audiogram Each dot = 1% # of dots above a pts threshold

is the audibility index revealingthe percentage ofconversational speech energyaudible to the pt at a distance of3-6 feet. If word recognition is poorer than

prediction: neural hearing loss orcentral disorder.

Counting Dots: ((Mueller &Mueller & KillionKillion))

Calculating AI from thisaudiogram is simple.This Figureshows a patients audiogramsuperimposed on the count-the-dots audiogram.

Those components of averagespeech that are below (or at higherintensity levels than) theaudiogram are audible to thepatient, and those that are aboveare not.

To calculate the AI, simply countthe dots that are audible to thepatient. In this case, the AI is 60(or 0.6).This essentially meansthat 60% of average speech isaudible to the patient.

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AI clinical applications The AI has at least three useful clinical applications.

It can serve as an excellent counseling tool for explaining to apatient the impact of hearing loss on the ability to understandspeech.

The AI has a known relationship to word-recognition ability.Thus word-recognition scores can be predicted from the AI or,if measured directly, can be compared to expected scores basedon the AI.

AI can be useful in hearing aid fitting in serving as a metric ofhow much average speech is made audible by a given hearingaid.