Introduction: habitual pitch perception associated with the mean fundamental frequency of speech. In the clinical evaluation referred to this issue is dealt with in the normal range for a person whether he is a habitual pitch. A common feature in many of the abnormal pitch of voice disorders, the assessment of habitual pitch and factors affecting it, may help scientists to determine the existence and degree of voice disorder. The present study aimed to investigate the effect of speech sample duration, the person is a habitual pitch.

Methods: In the present study, no natural base frequency of 30 female speech sound disorder, aged 18 to 30 years using praat were using a counting task in 60 seconds - that's three times and then averaged in -, was obtained. Participants also must have to fulfill the inclusion criteria of the study.  

Results: The mean baseline frequency words ranged 0-1 seconds: 218.87± 19.22, in the range 0-5 seconds, 211.00± 19.56, in the range 0-15 seconds, 202.65± 19.50, 219.07± 105.49 in the range 0-30 seconds. in the range of 0-60 seconds when it was 215.86± 103.33. Repeated measures ANOVA showed a statistically significant relationship (s) has base frequency speech range (p&ge 0.001 F=47.136).
Conclusion: the results show that duration of speech sample has effect on habitual pitch measure.