PIPB Function – Procedure and Application: Patient’s speech recognition performance depends on the intensity of the test materials. It is called the PIPB ( Performance Intensity Phonetically Balanced) Function Test when phonemically balanced PB words are used.
‘Articulation curve’ is the investigation of the relative intelligibility of spondee at various intensity levels. The examination of the hearing for phonetically balanced words at various intensity levels is referred to as the PIPB function.
Purpose of PIPB Function Test:
- To assess patient speech recognition ability in the form of the percentage of words repeated correctly at a specified level of presentation.
- It helps in determining the level of presentation of speech signals in speech discrimination tests, as well as some special tests for the central auditory nervous system.
Procedure of PIPB Function Test:
- Instruct the client that you will hear some words through headphones, and you have to repeat the words(PB words)
- The test begins by varying the intensity at which the words are presented.
- Taking PTA of 3 frequencies, 500, 1000, 2000 Hz, and increasing intensity in 10dB steps till the plateau is reached or performance/discrimination score reaches 100% or maximum.
- There is a reduction of speech recognition scores that occurs at intensities above where PBmax is obtained, called rollover of the PI function/PI Rollover.
- Further increasing the intensity results in the lowest speech recognition score over PBmax, which is known as PBmin.
Interpretation of PIPB Function Test:
The scores are interpreted in the form of Rollover Index (RI) (Jerger and Jerger, 1971).
RI = PB max – PB min / PB max
Figure 1: The Performance-level function of a normal-hearing individual whose maximum speech recognition Score (PB max) is 100%.
Figure 2: Some of the different kinds of performance-intensity functions.
- (a) The same normal PL Function as in Figure 1.
- (b) The same normal PL function shifted to the right by 30 dB HL for a conductive loss.
- (c) The PL function from a subject with sensorineural impairment, whose threshold falls at PBmax of 80%.
- (d) The PL function of an example of an SSE with maximum PBmax = 76 % at 70 dB HL in an individual with sensorineural loss that shows some rollover as intensity increases.
- (e) A PL function with PBmax 64% pathologic rollover in a patient with retrocochlear disease.
Figure 3: That’s the PL function with weird rollover from figure 2; now it shows PBmax and PBmin and how the rollover Index is calculated.
Application of PIPB Function Test:
- Help in determining the site of the lesion (to rule out RCP)
- Assess central auditory function
- Plan and evaluate aural rehabilitation programs
- Evaluate HA candidacy and select appropriate amplification.
References:
⇒ Essentials of Audiology – Stanley A. Gelfand, PhD (Book)
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PIPB Function – Procedure and Application
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