It's easy to define accuracy, hard (impossible) to achieve. Compare the waveform going in to the waveform coming out. The closer the output is to the input, the more accurate the speaker.
Many factors are involved in accuracy. All forms of distortion, harmonic, intermodulation, linear, phase, time. Not all forms of distortion are equally audible or important from a psychoacoustic standpoint. Other factors include, the stored energy of the drivers, the cabinet resonances, refraction, and interference patterns.
Room variations and anomolies must be eliminated for a true measurement. But, of course, the room comes into play for the user. This brings up another factor, power response. How does the speaker 'light up' the room, and how well does the ambient sound field correspond to the direct sound? Speakers can measure very well on axis, and create a miserable sound field that colors everything.
These factors also need to be prioritized. Suggested priority:
1) Linear response
2) Harmonic and IM distortion
3) Stored energy
4) Power response
5) Phase and time
Many factors are involved in accuracy. All forms of distortion, harmonic, intermodulation, linear, phase, time. Not all forms of distortion are equally audible or important from a psychoacoustic standpoint. Other factors include, the stored energy of the drivers, the cabinet resonances, refraction, and interference patterns.
Room variations and anomolies must be eliminated for a true measurement. But, of course, the room comes into play for the user. This brings up another factor, power response. How does the speaker 'light up' the room, and how well does the ambient sound field correspond to the direct sound? Speakers can measure very well on axis, and create a miserable sound field that colors everything.
These factors also need to be prioritized. Suggested priority:
1) Linear response
2) Harmonic and IM distortion
3) Stored energy
4) Power response
5) Phase and time