How the different frequencies are reproduced in a system. The human ear, at its best, has a frequency response of about 20 Hz to about 20 KHz (20,000 cycles per second). Good electronic audio equipment may have a response of 20 Hz to 20 KHz plus or minus 1 dB.
The frequency response indicates how much of the audible range can be accurately reproduced. The human ear responds to frequencies from approximately 20-20,000 Hz
The range of frequencies over which a device operates as expected. (Course material/Ultrasonics/EquipmentTrans/tranducertesting2.htm)