If you want an unimpeachable sound-level measurement, this is the tool to use! No one can argue with a reading from a General Radio Sound-Level Meter.

Unfortunately the GenRad 1565-B costs $3,524 when new, and the carrying case would be extra (see the 1565-B listing on the IET Labs website).  The meter on sale here is not new, but it is in excellent condition, and it is much less expensive!

GenRad 1565-B Sound-Level Meter Specifications

+ Sound Level: 40 to 140 dB re 20 µN/m2

+ Weighting: A, B, and C. Conforms to ANSI S1, 4-1971 Type 2 and IEC651.

+ Meter: rms response with fast and slow speeds.

+ Input: MICROPHONE: Lead-zirconate-titanate ceramic.

+ Power: Two 9V alkaline batteries (supplied) provide ~50 hours of operation.

This meter comes with the 58-page "Instruction Manual" (aka User and Service Manual) and it also comes with a fitted soft case (see the photos). The Manual is slightly warped because of the way it fits in the case with the meter.

The GenRad 1565-B is a general-purpose sound-level meter that conforms to both national and international standards, meets all criteria necessary for the noise previsions of the Occupational Safety and Health Act (OSHA) and includes features found in more cumbersome sound-level meters. This sound-level meter is also approved for use in gassy coal mines by the bureau of mines. The 1565-B sound-level meter fits in the palm of your hand, and operates in severe environments for up to fifty hours using standard 9V batteries. There are no line or microphone cords to trip over or bother with, and the ergonomically designed controls permit one hand operation and rapid interpretation of the results - just aim and read. A rugged, laboratory-grade ceramic microphone is used on the 1565-B Sound-Level Meter. The instrument is housed in a tough plastic case, tapered at the microphone end to reduce the effects of case diffraction and meets all ANSI-2 requirements for General Purpose Sound Meters. An output jack is provided for use with headphones or recorders, and a lock is provided so the range control can be fixed in a single position. This popular meter weighs less than 1 pound, features simple push button operation, battery power, and a rugged ceramic microphone.