Md. Code Ann., Cts. & Jud. Proc. § 10-911
In any legal proceeding of any nature, the quantities and qualities of noise may be proved by evidence of tests made with any instrument designed and constructed to measure and indicate or record the presence of sound, including such devices commonly called sound level meters and frequency analyzers.
Added by Acts 1974, c. 287, § 4. Amended by Acts 1977, c. 35.