I was thinking today about the parallels between transmitting antennas and speakers. They both sort of do the same thing: radiate. Antenna polar response is measured in an EMC chamber; a speaker in an acoustically anechoic chamber. The same measurements are taken albeit at different frequencies, amplitudes and test methods and equipment.

With these measurements, we know how antennas and speakers will behave in free space or in a room. Antenna direct response is analogous to the listening window and total radiated power is analogous to sound power. When the direct response and total radiated power are amplitude and phase-matched, directivity will be unity which means the antenna is omni-directional - analogous to the listening window and sound power being amplitude and phase-matched. Sometimes you want an omni-directional antenna or speaker and sometimes not depending on the application. For a consumer speaker in a room, omni is what we want.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated