Refer employee to company hearing conservation program for medical monitoring and training. If you don't have one, you should. Temporary construction workers are often left out when it comes to inclusion in effective hearing conservation programs. Audiometric testing to detect hearing loss is usually not required by OSHA until after six months of employment. Many projects do not last that long.
Some firms take a proactive approach and test temp.
This is rare. Most do nothing at all except issue ear plugs. I am not sure what is offered by the local union halls. In any event, WC claims associated with hearing loss are the responsibility of the present employer. This should be enough motivation for employers to take proactive steps at periodic monitoring of site noise levels, training, PPE, audiometric testing, and other controls.