A certificate is not a requirement for competence - being able to do the job with accuracy and completeness and achieving the desired outcome is more important.

I suggest that if you have been doing noise assessments on a regular basis and still know what you are doing then keep doing it.

If however, like me, you have only periodically used your abilities since you were awarded the Cert many years ago, you may have reduced competency whilst retaining enough ability to be dangerous!