Measurements were made in order to evaluate the pressure level of sound generated by a grille in an airflow. A streamlined probe microphone, which is covered by a solidified glass fiber of high density, was used for detection of noise existing in the airflow. Distributions in a flow duct of the turbulence‐fluctuated pressure of the airflow and of the output level of the microphone were measured and then compared with sound transmission characteristics specified in the duct. It was found that the distribution of the microphone output agrees with the sound transmission characteristics, but not with the fluctuating pressure of the airflow. As a result, the levels of the sound pressure generated by a grille were about 50 dB (re2 × 10−4μbar) at frequencies greater than 200 Hz, with a maximum value of 65 dB at 1250 Hz, for a flow velocity of 8.4 m/sec. It was also found that the output of the probe microphone produced by the turbulence‐fluctuated pressure of the airflow can be reduced to 40 dB below the turbulent pressure level by a covering of this type.