Don't send a man to do a meter's job
I agree that the quality of any equipment should come up to the mark. If a specification says that a signal-to-noise merit must be no less than 70dB, it must be, but one of our standards included a requirement about audio-hearing control that was to be tested by ear.
Personnel from the quality control department used headphones to test each music center. You can agree with me that it is difficult for people without a delicate ear for music to feel all nuances of music, but this testing was presented in our situation because the factory never manufactured musical equipment before.
I can say that almost everyone in the quality control department had tin ears. We had high-pitched arguments with them about this problem. They would argue that they may not feel all nuances of music, but they could hear! They said that hearing noise does not need a delicate ear for music, and unfortunately all of our big bosses agreed. This caused a real headache, because this testing was very subjective.
One day, our team of development engineers headed to the assembly shop because the engineer of the quality control department again heard noise while checking a device. I brought measuring equipment and showed that the level of noise was in the specific norm with a good margin, but the engineer said, “I hear noise and this device will be condemned.” I again showed the specification and measurement of the signal-to-noise. All was in the norm, but he said that the standard requirement was to check devices by hearing and he heard strong noise. Our manager and one from the quality control department had to be called in.
Many people stood near this music center and checked the noise of the device by ear. One of our engineers asked, “Which of the channels has more noise?” The quality control engineer answered with confidence, “The most noise is in the right channel.” We asked him listen once again, very thoroughly. He was still sure that the noise in the right channel was more and it had an inadmissible level. The head of quality control took stereo-headphones too. He heard noise and confirmed the fully inadmissible noise in the right channel.
Before the test, our engineer disconnected the control headphones and placed the connector in his pocket. We showed them that the headphones were connected to the pants pocket of our engineer, not the product, all this time. It was a shock!
I understand it wasn’t the best idea for young engineers to fool the managers, but all's fair in love and war, isn’t it? We never had any problems after this incident as products were checked only by using measuring meters.