How To Measure A Room’s Frequency Response – www.AcousticFields.com

How To Measure A Room’s Frequency Response – www.AcousticFields.com

August 26, 2019 15 By Kailee Schamberger


Hi everyone, I’m Dennis Foley from Acoustic Fields. Today we’re going to talk about room frequency response. A lot of enquiries from customers about the room that they have, it has this size
they have the sources, sound sources in the room. They have these low frequency drivers
with these diameters. A lot of them don’t go through the next step and measure the room
response but you know obviously we can predict a
little bit with dimensions and sound sources and things like that, but some do have measurements and this is an issue I see all the time
that’s confusing for them. So let’s talk a little bit
about it. Let’s say you run a room frequency response and what is that?
Well that’s the signature of the room, that’s how the room reacts to sound energy that’s put with in it.
That’s its signature just like when you sign your name to a document, to a cheque, a
contract or anything like that, that’s your signature authorizing it. Well
this is the room authorizing the sound that’s in it. And this is a picture of how it’s
authorizing in that manner okay? And usually it’s not smooth because
today’s rooms are very small so there’s a lot of issues that we have to address. A common graph that I see in rooms that are measured our peaks and troughs so we have high points and
low points. If we take this as our baseline in our
center measurement we have energy signatures above the line and we have energy signatures below the line. Now what do those two energy signatures have
in common? What does a peak of plus 10 DB and a dip of minus 10 DB have in common? What do both of these areas have in
common? Well the one thing they have in common is pressure. These signatures are both reactions, the rooms reactions, to certain
frequencies, say here and here, the room reaction to 500 and 200
cycles. So it really doesn’t like 200 and it
really doesn’t like 500. Now what way does it not like those? Since they’re both pressure related, one
is an exaggeration, one is an attenuation, or lack of energy. You can’t EQ your way out of these. You
can’t dump 500 cycle energy into this pressure area
and bring it back to normal, not of its -10, -15 DB you can’t do it. You could blow your EQ up trying, but the room simply
won’t let you so both of these peaks and troughs are
reactions to pressure. You squeeze your lips together and then
blowout and your cheeks expand that’s how your room is reacting to
pressure. That’s how the room is reacting to 200 cycles in our example here. So it’s all about pressure. So how do we
manage that pressure? Well that’s where different sound
absorption technologies come in. So if this is a common situation that we
see, what’s a good graph to look at? Well we want something like this. We want something plus two or minus two over our baseline. Not easy to achieve but not difficult. Most your professional recording studios, most of your top engineering design firms use this is a a guideline. So it’s a good
marker. You can see in our top examples, and
this is typical of some of the room responses that we receive, big, big difference. This is minimal room sound. This is lots of room
sound. Thank you.