The goal in loudspeaker design is to maximize the amount of acoustic power available from the device, given the constraints and trade-offs between the available parameters. One acoustic watt is equivalent to 107.5 dBSPL at around a meter from an omnidirectional source. Q, therefore, is a parameter of the horn, not the driver. This is quite useful, since it allows more energy on the audience and less on the walls and ceiling. The power of different sources of sound can vary widely.
Different sources can also produce sounds with varying spectral content.
A very shrill gas leak may produce the same sound power as a lawnmower, but they will be two very different sounds. Later, we will see how to take this into consideration when determining sound levels.