# How to measure Room Gain? anechoic vs. in room measurement?

#### Plompudu

##### New Member
I'm currently trying to figure out how much room gain i get in my "casual movie watching/gaming room", so that i can choose a fitting subwoofer for some infrasonic Bass, when I've got some money saved up.

My room is 4.5m x 2.7m x 2.5m -> Room Gain should start at ~38Hz.

My Though process was that i can measure the slope of the response of a Setup/Subwoofer in my room and compare it to the anechoic response to figure out the Room Gain.
Is that a good way to do it? If not how can i do it better instead?

My Subwoofer (SVS SB-1000) has a anechoic response that has a 32dB/oct Slope below 20Hz, F3 at 24Hz:

Here is what i measured in my room (with and without some EQ), but I don't know what level to set the anechoic (green) at for a fair comparison and what range to chose to get the slope / calculate the Gain.
Problem with that measurement at my MLP is the Room mode at 34Hz that makes it hard to see where the Gain starts.

If i choose the slope like this it would mean that I get ~11.12dB/oct gain which seem like it's too high, cause 12dB would be the case in a perfectly sealed room. Is my method too inaccurate? (32db/oct - 20.88dB/oct = 11.12dB/oct)

What would you say is my room gain? (if it's possible based on my quick measurements)
Any input on the topic and/or sources other than ASR would be appreciated! (I already looked through all i could find here)

I've found a more intuitive way to choose the slope and would appreciate feedback on this method!

2. import the anechoic response
3. go to All SPL / Controls / Trace arithmetic
4. select A/B with A being the measurement and B the Anechoic response
5. SPL&Phase - Shift+click in the range you wanna figure out the slope

This time with more accurate measurements cause i took more measurements to create the averages. (Right Channel + Subwoofer playing at my MLP)
Results:

I get ~7.73dB/oct Room Gain using this method, which seems way more reasonable than my first results!

Does anyone know a good way to add a certain amount of dB/oct below 38Hz to anechoic measurements, so that i can compare different Subwoofer easier using a estimation for in room performance?

Does anyone know a good way to add a certain amount of dB/oct below 38Hz to anechoic measurements, so that i can compare different Subwoofer easier using a estimation for in room performance?
Use EQ to make the adjustment, then export the result as a new measurement? You can use the export as a house curve as well I think.

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