Sound is measured in decibels (dB). For the human ear, it is possible to perceive changes in sound as low as 1 dB. To put this into context, a human whisper generally weighs in at 20 on the dB-based scale, while normal conversation stands at around 60 dB. And too long...
There are two acoustic ratings based on sound transmission: OITC and STC. The OTIC is a relatively new way of measuring sound transmission, including information about how well the glass acts as a barrier.
Therefore, the port glass needs to meet certain standards. If the port window glass and frame used are of cheap quality, it will essentially affect the result.
