- Jan 24, 2020
- .de, DE, DEU
Would this happen if the speaker were measure using the balcony behind the rooms, placed in the wood rod, thus 4m above the ground?
The (1) marks the floor of the balcony, which is 1m deep, so there would be a wall 1m behind the speaker:
The first thing you always have to ask yourself when measuring a loudspeaker is where is the nearest reflecting surface (even "small" surfaces count: chair, table, box, observer standing around, grill, protruding ceiling beam, cat, dog, mutated spiders, hollow man - not sure, ...) and how much longer is the time of flight of this first reflection compared to the direct path from the loudspeaker to the microphone - where the reflecting surface is located (top, bottom, left, right) doesn't matter.
Surface size does matter, but even small surfaces create a footprint in the frequency response.
The difference in time of flight of the first (closest) reflection, minus the direct time of flight LS to Mic, gives the gate for the quasi anechoic measurement.
If we look at the measurement situation on your balcony from above (view from the top), the following results:
The first incoming reflection has a 2m longer path than the direct sound (LS to Mic).
This results in a gate of 5.8ms and a reflection-free measurement down to 170Hz (but there with very strong smoothing of 1/1oct at 170Hz).
Update: And as said above, any increase in baffle size will affect the measurement, so the floor height of your balcony would also affect the measurement a bit.