Hi Hossein,
(This is an edit of my previous response, please disregard that one)
I apologize for the delay with the US Thanksgiving Holiday last week.
Table 21 described in the datasheet would need to be matched up to the HW configuration I2C address option in SigmaStudio when you to connect the USBi to the target.
To verify, I connected up a logic analyzer to the USBi's I2C signals connected to the EVAL-ADAU1x61 eval board and also see address "0x38" is read/interpreted by the logic analyzer. However, if you look closely, you will see that the address byte data relative to the I2C clocks is 0 1 1 1 0 0 0 0 for I2C writes, which matches table 23 and figure 49 in the datasheet.
Can you verify the I2C data on the bus to make sure it matches this format as 0x70 (for a device with ADDR0 and ADDR1 tied to ground)? Perhaps it could be that your particular microcontroller interprets the I2C address byte as 0x38 (shifted then 1 bit to the left) and combined with the read/write bit "0" prior to transmitting the data to the ADAU1761? My analyzer seems to remove the R/_W bit and display the address as 0x38, but the data on the bus is displayed as 0x70.
-JT