New types of characteristics parameters calculated from the spectral properties show a strong potential to allow a much better classification and judgements of the actuators:

Signal-to-Noise Ratio (SNR)
This classification quantifies the distortion in the relationship between the input signal and the cleanliness of its reproduction, reflecting the fidelity. (It must be noticed that perceptual aspects are not considered in this definition. A low SNR may still create an excellent and impressive feedback, just it may be the result of a combined impression of multiple frequencies. of the output signal to the original input.)

Power Linearity (PL)
This classification describes the proportionality of the
distribution of the maximal mechanical power output in
relation to the input voltage of LRAs and its deviation
from linearity.

Mechanical Power Class (MPC)
This classification describes the dominant frequency
range of the maximum mechanical power output of LRAs
in relation to its mechanical peak output. For ERMs, the
input voltage of the rising edge in the mechanical power
curve is described with this classification.

Power Density (PD)
This classification describes the relation between the
component’s installation size in volume and its maximum
power output.

Control Dependent Drift (CDD)
This classification describes the drift of the resonance
frequencies measured in the unloaded state of different
input voltages and in the loaded state, respectively.

Resonance Bandwidth (RB)
This classification describes the bandwidth of frequencies
at the half-power point for a single input voltage in both
the unloaded and loaded states, respectively.

Load Dependent Drift (LDD)
This classification describes the bandwidth of the resonance frequencies measured between the unloaded and
loaded state of the same input voltage.