How does the ohmage measurement relate to sensitivity?
j/k I just had to use "ohmage" at least once. That is all.
Sensitivity is typically measured by applying a specific voltage (2.83 volts) to an 8 ohm speaker, giving a 1 watt power dissipation when the speaker is actually at its nominal impedance of 8 ohms. In sensitivity tests for 4 ohm speakers, the same voltage is applied, but the driver dissipates 2 watts (remember, P = V^2/R), so no longer are you given a rating for the SPL at 1 watt of input. You would need to subtract 3dB from the rating to compare your 4 ohm driver to your 8 ohm driver if this is how they're measured.
Of course, applying 2 volts to the 4 ohm driver will make it dissipate 1 watt and there you have a good basis for comparison again.
This comment entirely ignores that you will almost never see a speaker or multi-driver enclosure reach its nominal impedance. It will vary significantly from slightly below nominal to well above nominal depending on frequency. Hence, the sensitivity can and does vary due to this parameter within the speaker's passband, although this is definitely not the only parameter affecting a driver's frequency response.
BTW, everytime the word "ohmage" is used, a puppy dies.
