Post by Hexspa on May 18, 2016 6:52:47 GMT
Ethan, you've said:
There are three separate factors that determine the response at any given location in a room.
First is the room's natural resonances, or modes. These are independent of speaker and listener placement, and the frequencies are determined entirely by the wall-wall and floor-ceiling spacings. If you stand in an empty stairwell and clap your hands, you'll hear a "boing" sound whose pitch is usually determined by the spacing between the walls. Whether you stand near to one wall or the other, or crouch down low or clap your hands high above your head, the pitch of the "boing" remains the same. That is the mode frequency.
The other two factors are SBIR and LBIR - Speaker-Boundary Interference Response and Listener-Boundary Interference Response. These are the classic 1/4 wavelength related peaks and nulls whose frequencies are based on the distance between each speaker and each boundary, and from the listener and each boundary.
The response at any given cubic inch in a room is the sum of all three of these factors, and that's a lot of variables given two speakers, one listener, and six boundaries. There are programs like RPG's RoomSizer that attempt to calculate the response based on all of these variables, but I've never tried them. People I trust say they're somewhat useful as a starting point, but they never give the same results as actually measuring with a microphone and meter etc.
So does that mean the response I get in software is a function of these three factors? Essentially I must weigh all three to understand why the response is what it is? I can't just rely on one then. So if I have a null at 60 Hz, it could be due to my room not having a supporting mode, my speakers' placement or my actual measurement position?
Sounds tricky.
Thanks,
-m
There are three separate factors that determine the response at any given location in a room.
First is the room's natural resonances, or modes. These are independent of speaker and listener placement, and the frequencies are determined entirely by the wall-wall and floor-ceiling spacings. If you stand in an empty stairwell and clap your hands, you'll hear a "boing" sound whose pitch is usually determined by the spacing between the walls. Whether you stand near to one wall or the other, or crouch down low or clap your hands high above your head, the pitch of the "boing" remains the same. That is the mode frequency.
The other two factors are SBIR and LBIR - Speaker-Boundary Interference Response and Listener-Boundary Interference Response. These are the classic 1/4 wavelength related peaks and nulls whose frequencies are based on the distance between each speaker and each boundary, and from the listener and each boundary.
The response at any given cubic inch in a room is the sum of all three of these factors, and that's a lot of variables given two speakers, one listener, and six boundaries. There are programs like RPG's RoomSizer that attempt to calculate the response based on all of these variables, but I've never tried them. People I trust say they're somewhat useful as a starting point, but they never give the same results as actually measuring with a microphone and meter etc.
So does that mean the response I get in software is a function of these three factors? Essentially I must weigh all three to understand why the response is what it is? I can't just rely on one then. So if I have a null at 60 Hz, it could be due to my room not having a supporting mode, my speakers' placement or my actual measurement position?
Sounds tricky.
Thanks,
-m
