RTA Pro measuring road noise: should I use the C filter or the A filter?-Acoustics Forum-Acoustic Fields Forum

I have an audiophile friend that recommends using the C filter but in a “silent” room low frequencies are registering 50 dB or higher. I suppose that means my ear cannot hear them. And the relative change in dB once a barrier is constructed is what matters. I’m talking myself out of using the A filter as I type.

Thanks all!