CODI 504  Voice Disorders
Information Sheet on Measures to Estimate Airflow

  Predicted Maximum Phonation Time

It is possible to estimate or predict a patients MPT (in seconds) by using the formula VC/110 X 0.67 for males and VC/100 X 0.59 for females.  Use this measure to compare actual MPT to the predicted value.  When the ratio of a patient's actual MPT to predicted MPT is less than 0.70, it may indicate either inefficient glottal control (manifested as breathiness) or inefficient respiratory function.

Source: Prater, R. and Swift, R. (1984).  Manual of Voice Therapy.  Austin, Tx: Pro-Ed. (P.39)

Estimated Mean Flow Rate (EMFR)
 

This is an aerodynamic assessment of vocal function that allows the estimation of mean flow rate using hand-held spirometers (dry spirometers) to measure vital capacity and a regression equation determined by Rau and Beckett (1993).  The first step is to determine vital capacity and maximum phonation time.  Using these two measures you will next find the phonation quotient (PQ) using the following formula.

             VC (in milliliters)
  PQ =   ------------------
             MPT (in sec)

Then use this value in the following equation to give you the EMFR.

  EMFR = 77 + .236 (PQ)
 

Norms
Male
VC
MPT
PQ
EMFR
 Mean
4.185
31.6
135.0
109.00
SD
.875
7.94
19.3
4.59

 
 
Female
VC
MPT
PQ
EMFR
Mean
3.019
24.6
125.8
107.00
SD
.319
5.45
16.4
4.03

Rau, R. & Beckett, R.  (1984).  Aerodynamic assessment of vocal fold function using hand-held spirometers.  Journal of Speech & Hearing Disorders, 49, 183 - 188.

Predicted Normal Forced Vital Capacity (FVC)

Note: Age in years, height in centimeters

Women :  PFVC in mL  = [27.78  - (0.101  X Age)]  X Height

Men:  PFVC in mL  =  [27.63  - (0.112  X Age)]  X Height
 
 

Children

Height Range                                   Formula
Girls                    98 - 113                             PFVC = (27.8 X Height) - 1900
                          118 - 138                             PFVC = (32.2 X Height) - 2400
                          143 - 163                             PFVC = (43.2 X Height) - 3970
                          168 - 173                             PFVC = (26.5 X Height) - 1200

Boys                   98 - 118                              PFVC = (27.4 X Height) - 1770
                         123 - 148                              PFVC = (40.0 X Height) - 3330
                         153 - 173                              PFVC = (63.0 X Height) - 6730
                         178 - 188                              PFVC = (30.0 X Height) - 1050

Source:  Orlikoff, R. F. and Baken, R.J.  (1993)  Clinical Speech and Voice Measurement:  Laboratory Exercises.  San Diego:  SingularPublishing Group

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