Background and Aim:  Among all auditory assessment tools, auditory steady state response (ASSR) is a modern test. Modulation frequency for this test is usually 80 Hz. The purpose of this study, was to examined adult subjects with 40 Hz and 80 Hz ASSR and compare the results.
Materials and Methods: Thirty adult (60 ears) were evaluated by ASSR and PTA test, Results were divided into three groups: normal hearing, mild and moderate sensorineural hearing loss.
Results: In all groups, forty hertz ASSR thresholds were relatively closer to behavioral threshold than those of 80 Hz ASSR(p<0.05). Besides, the more severe hearing loss, the lower the difference between those two thresholds. Correlation coefficients were also higher in 40 Hz ASSR(p<0.05).
Conclusion: Frequency modulation thresholds with 40 Hz are more likely to be closer to the behavioral thresholds. Moreover, it has better results than the thresholds with 80 Hz.

Background and Aim: Previous studies suggest that auditory stimulus frequency in normal subjects contribute to both P300 amplitude and latency measures. As occipital cortex devotes to other modalities including auditory inputs, the purpose of this study was to determine the effects of stimulus frequency in early blind subjects.
Methods: fifteen early blind subjects (8 males and 7 females) with mean age of 25.13±4.27 years were tested. Cognitive potential P300 was recorded in response to high (1000/2000 Hz ) and low (250/500 Hz) frequencies auditory stimuli using an oddball task in 70 dB nHL. While participants answered to target stimulus, amplitude and latency of P300 was recorded.
Results: With high frequency stimuli, mean amplitude in early onset blind subjects obtained 14.13 ±5.53µv and was 17.59±8.17µv with low frequency. With high and low frequency, mean latency of P300 obtained 295.60±31.33ms and 317.38±21.71ms respectively.
Comparison of results between two stimuli showed that there were statistically significant differences between amplitudes (p=0.008) and latencies (p=0.001) of cognitive potential P300.
Conclusion: Changing low frequency to high frequency results in decreasing both amplitude and latency. It seems that auditory stimuli frequency affect the P300 parameters in blind subjects.