“Are acoustical lab tests really objective? If a company is paying for the test, don’t they just get the test results they want?”
While some very competent material testing can be informally conducted by a manufacturer’s own lab, no one outside of that company will give any credibility to such data.
In general, objective data comes from a National Voluntary Laboratory Accreditation Program (NVLAP)-certified acoustics laboratory.
An independent lab lives or dies based on objectivity. Underwriters Laboratories is one example of these certified labs. Any given lab handles hundreds of tests annually. These tests get called into lawsuits all the time. Lack of objectivity means they lose all credibility, their certification is pulled and the lab is out of business. Someone may face jail time.
The labs themselves are closely governed by the NVLAP and must comply with a strict set of standards. Daily logs of environmental conditions, maintenance logs of all equipment maintenance, calibrations and more are required to be on hand at all times. NVLAP will routinely inspect labs for compliance.
It is illegal to tamper with any test or test report. So falsifying data or rigging a test result will cause NVLAP to pull their certification, essentially shutting down the business, and someone could see jail time. It’s just not worth the risk and labs are very concerned and on alert.
Lastly, the test procedures themselves are highly scripted and defined by yet another governing body, the ASTM. The American Society for Testing and Materials (ASTM).The ASTM describes exactly how every test will be conducted so that the results can be reproduced in another lab. There is an ASTM test standard for virtually everything, well beyond acoustics. If you want to have the shear strength of a bolt tested, there is an ASTM standard test for that. If you want to test an air conditioner, there is a standardized test for that as well.
In summary, an independent NVLAP certified test is completely objective.