A decision has been deferred on whether to allow aircraft engine testing on the ground at Norwich Airport.
For the last five years KLM UK engineering has been testing at Norwich airport on an unauthorised site.
The airport's management would like to move the facility and they have applied for planning permission.
But Norwich city councillors listened to claims the tests can reach 80 decibels and decided they need to hear the noise for themselves.
An environmental health officer will accompany them to monitor noise levels.
The city council's planning committee will then make a decision.