Speech Audiometry

In addition to pure-tone audiometry, speech audiometry is a set of behavioral tests that provide information concerning sensitivity to speech materials and understanding of speech at supra-threshold levels. It can be used diagnostically to examine speech-processing abilities throughout the auditory system, and it can be used to crosscheck the validity of pure-tone thresholds.

Speech Audiometry Stimuli: Recorded or monitored live voice. Live is quicker and more flexible but recorded is more consistent and controlled. Live presentations also have the advantage of building quick rapport through verbal interplay. Patient's Role: Patient must be familiar with words being used and have ability to respond via verbal or written reply or identification of an object/ picture (especially for children or aphasics).

Speech Audiometry Clinician's Role: Give good directions! Don't give visual cues (such as lip movement) while doing testing especially for live speech presentations. Test environment: Two-channel audiometer with facilities for input from microphones and CD players/external devices. Two-room setting.

Types of tests Speech Threshold Testing: 2 types SDT (speech detection threshold) SRT (speech recognition threshold)

Speech Detection Threshold (SDT) Also called speech awareness threshold (SAT). Objective - to obtain the lowest level at which speech can be detected at least half the time. This test does not have patients repeat words; it requires patients to merely indicate when speech stimuli are present.

SDT The SDT is especially useful for patients too young to understand or repeat words. Sentences are preferred over isolated words. The speech should be presented monotonously Cold running speech The SDT may also be used for patients who speak another language or who have impaired language function and/or speech disorder.

SDT Present continuous discourse and raise and lower level by bracketing (down 10, up 5) until you find the level at which they detect it. Patient may respond verbally or by pushing a button or clinicians observes for facial/ body expressions (for infants).

SDT For patients with normal hearing or somewhat flat hearing loss, this measure is usually dB better than the speech-recognition threshold (SRT). For patients with sloping hearing loss, this measurement can be misleading with regard to identifying the overall degree of loss. The SDT will be closely related to the threshold for the lower frequency, and it will not indicate greater loss in higher frequencies.

The Ling Six-sound Check Is a behavioral listening check to determine a cochlear implant’s or hearing aid’s effectiveness. The sounds ah, ee, oo, sh, s, and mm indicate a child’s ability to detect all aspects of speech as these six sounds encompass the frequency range of all phonemes. This check can be used to determine what sounds the patient is able to detect, discriminate, and identify. Detection - Recognizing the presence or absence of sound Discrimination - Discerning if two or more sounds are the same or different Identification - Reproducing a sound or pointing to a picture of the sound heard

The Ling Six-sound Check Can be presented as live voice (calibrating the distance between the speaker and patient) or via an audiometer. Ling Sounds

Speech Recognition Threshold (SRT) Also referred to as the speech reception threshold. The objective of this measure is to obtain the lowest level at which speech can be identified at least half the time. Preferred over SDT. Typically use spondaic words. Spondee. Two syllables, both pronounced with equal stress and effort. E.g. baseball, hot dog, toothbrush, cowboy.

SRT Method Use live voice or prerecorded stimuli. May or may not use a carrier phrase "say the word". Familiarize patient with word list to ensure that all the words used are within the vocabulary of the patient. After you familiarize them, use the tracking procedure to determine the threshold. Although not commonly used, SRTs can be tested with BC. Children who do not like to ‘play’ with tones.

SRT Method SRT are used to validate pure-tone thresholds because of high correlation between the SRT and the PTA. In clinical practice, the SRT and PTA should be within +/- 6 dB. Other clinical uses of the SRT include establishing the sound level to present supra- threshold measures (such as word recognition test) and determining appropriate gain during hearing aid selection.

Relationship between Pure-tone thresholds and Speech Recognition performance - Articulation Index (AI) The Articulation Index or AI gives a measure of the intelligibility of hearing speech in a given noise environment. An adoption of the AI concept is to quantify communication difficulties based on pure-tone thresholds. The basic interpretation of the AI value is the higher the value then the easier it is to hear the spoken word.

Count the dot method - Mueller and Killion (1990) Each dot represents 1% of the information contributing to speech clarity. The number of dots that are audible predict how well one understands quiet speech from a six foot distance. The dots are unevenly distributed, with many more of them filling in the gray zone between 1000 and 3000 Hz than in the 250 to 500 Hz area.

Count the dot method - Mueller and Killion (1990) Count the dots that are below audiometric threshold. The more dots that are below threshold, the better one is able to hear normal conversational speech. The fewer dots that below threshold, the more difficulty hearing conversational speech.

Articulation Index At least three clinical uses of the Articulation Index: To predict from the audiogram the amount of disability for normal-level conversational speech, Predicting the benefit that will be obtained from a hearing aid, and Comparing the benefit from one aid to another.

Supra-threshold measures Most Comfortable Loudness level The intensity level of speech that is most comfortably loud is called the most comfortable loudness level (MCL) test. Typically dB above SRT. This sensation level is reduced for many patients who have sensorineural hearing loss (SNHL). Use continuous speech. Gradually increase levels, starting at SRT. At each level, ask "too soft", "too loud", "comfortable". Bracket around. Monaural/binaural headphones or loudspeakers

Uncomfortable Loudness Level (UCL) This level provides the maximum level at which word-recognition tests can be administered. UCL can also indicate maximum tolerable amplification. Another reason to establish UCL is to determine the dynamic speech range. Dynamic range represents the limits of useful hearing in each ear and is computed by subtracting SRT from UCL.

UCL For many patients with SNHL, this range can be extremely limited because of recruitment (abnormal loudness growth – commonly seen due to a cochlear pathology). For normals, usually dB SL (ref SRT). Testing similar to MCL but to indicate when speech level becomes uncomfortable. Patient is instructed to signal when level is intolerable.

Word Recognition Testing The primary purpose of supra-threshold word-recognition testing is to estimate ability to understand and repeat single-syllable words presented at conversational or another suprathreshold level. Another use is to verify speech-recognition improvements achieved by persons with hearing aids. Comparing performance with and without hearing aids

Stimuli Phonetically balanced words A word list containing all of the phonetic elements of connected English in their normal proportion to each other. A number of different standardized word lists are available. PB-50, CID W-22 lists, NU-6 lists, PBK words (K-kindergarten).

Word Recognition Scores Words can be presented via tape, CD, or monitored live voice. Patients are asked to repeat words to the audiologist. Present PB words at a fixed level either MCL or dB above SRT. Typically present lists of 25 or 50 words. Get a percent correct score.

What does the score mean? Evaluation of Word Recognition Scores: % = good 75-90%= slight difficulty 60-75%= moderate difficulty 50-60%=poor. Difficulty in conversational speech. Less than 50% = very poor. Probably unable to follow running speech.

What can we do with kids? Prefer a closed-set testing than a open-set testing (ex, PB-K word lists). Some closed-set tests include Word Intelligibility by Picture Identification (WIPI): Child is presented with 6 pictures on a card and asked to point to the one that is said. Northwestern University Children's Perception of Speech (NUCHIPS): Similar to WIPI except 4 pictures appear on each card. Pediatric Speech Intelligibility test: Pictures

Problems with word recognition testing Problems with Word Recognition: - Poor test-retest reliability for SNHL. -Difficult to relate to everyday life. Suggested to test word recognition with competition (noise). Need to specify the Signal-to-Noise ratio (SNR or S/N) – difference in speech level and noise level. Different noise stimuli such as modulated noise, speech noise, multitalker babble, etc.

Review Speech recognition threshold Speech detection threshold Word recognition UCL MCL Special tests for kids