Background and Aim: As clinical audiometry assessment of each ear needs to know interaural attenuation (IA), the aim of this study was to investigate Persian speech IA in adults.

Methods: This cross-sectional, analytic study was performed on 50 normal hearing students (25 males, 25 females), aged 18-25 years old in Faculty of Rehabilitation, Tehran University of Medical Sciences. Speech reception threshold (SRT) was determined with descending method with and without noise. Then speech IA for Persian spondaic words was caculated with TDH-39 earphones.

Results: Mean speech IA was 53.06±3.25 dB. There was no significant difference between mean IA in males (53.88±2.93 dB) and females (52.24±3.40 dB)(p>0.05). The lowest IA was in females (45 dB) and the highest IA was in males (60 dB). Mother's language has no significant effect on speech IA.

Conclusion: We may consider 45 dB as the lowest IA for Persian speech assessment, however generalization needs more study on a larger sample.