Spl meter?

[MikeFord]

Everyone else has said most of what there is to say, but I will still add a couple points.

What is a SPL meter?

Its a microphone, usually of some level of precision for flat frequency response, a again precision level attenuator, an amplifier with eq and some features, with the output driving the meter.

The Radio Shack model was likely intended for safety personal to monitor hazardous sound levels and comply with regulations on exposure. It was identify areas where hearing protection would be required etc.

Meters for audio use were much more expensive and usually included peak levels, frequency displays, etc. Take the results of the Radio Shack meter with a grain of salt, its not bad, but its not renowned for accuracy even with using the correction table.

Band limited pink noise is my favored source, not too loud as tweeters don't like continuous higher levels, but loud enough that your test signal is well above ambient noise in the room.

The calibrated mics I've been looking at are USB, no preamp. I figure I will get one eventually, but have a RS and much higher quality Technics for simple level stuff.