Question about high pass and low pass frequencies

[robertwerden]

I was trying to find out how to measure the electronic hiss in a microphone and set the frequency on the low pass filter to the proper level to lessen it during live podcasting, as well as how to measure the frequency of room hums and rumbles to try and lessen them as well.

Is there a app that can measure these noises and tell me what frequency they are at so I don't have to just keep experimenting and wasting time?

I am using the Rode Rec app on my iphone as the recording device and Shure lav mics.

 

[TheDingo]

As a rule of thumb I always use an 80 Hz roll-off filter in post, as most sounds below this frequency are usually noise. ( the rumble from trucks driving by, the elevator in the office building, etc... )

I imagine it wouldn't take long to test a few different frequencies to figure out what sounds best to your own ears.

 

[Noiz2]

Actually there is an "app", Sound Tools has a spectrum analyzer in it. And as much as recording on the iPhone makes me kind of gag, this should be a good solution since it will be looking at the signal coming in through your mic.

BTW "experimenting" is not "wasting time" it's called "learning" and the more you do the better you get. You are still going to have to play around to find what sounds best, all an analyzer can to is show you where you have freq. activity. You still have to decide if it sounds bad when you cut it out. Also the "hiss" may just be the iPhone so you may not be able to remove it with out taking the files into a sound editor.