The human ear responds more to frequencies between 500 Hz and 8 kHz and is less sensitive to very low-pitch or high-pitch noises. The frequency weightings used in sound level meters are often related to the response of the human ear, to ensure that the meter is measuring pretty much what you actually hear. It is extremely important that sound level measurements are made using the correct frequency weighting - usually A-weighting.
'Bonanza,' 'Trapper John, M.D.' star Pernell Roberts dies. Pernell Roberts portrayed Dr. John McIntyre on Trapper John, M.D..
Enlarge. CBS. Pernell Roberts starred in the hit CBS series Trapper John, M.D. , in the 1980s. LOS ANGELES (AP)  Pernell Roberts, the ruggedly handsome actor who shocked Hollywood by leaving TV's Bonanza at the height of its popularity, then found fame again years later on Trapper John, M.D. , has died.He was 81.OS ANGELES (AP)  Pernell Roberts, the ruggedly handsome actor who shocked Hollywood by leaving TV's Bonanza at the height of its popularity, then found fame again years later on Trapper John, M.D. , has died.