Recording sound/screen capture while measuring decibel levels

[Further]

Iphone built in screen recording does not include ambient sound. For now i’ve had to film the phone with another phone next to a audio level meter used to calibrate to provide sound to the readings, this is a hazzle. I would love a feature where the decibel measurement was able to record a sound file simultaneously, or even better; that a screen recording included the sounds measured. Also, in expanded view the graph could show the number reading and calibration status, even in small type.

Thanx