impulse response: It should be used to make fundamental statements about the quality of a loudspeaker in terms of time behavior. A (theoretically infinitely) short voltage pulse serves as the input signal, which resembles a mere vertical line or "needle" in the measurement record.
The resulting speaker response will of course look different in the measurement diagram. The pressure profile is measured over time, the ordinate is described in pascals, and the time is on the horizontal. The steeper the impulse is traced in the first reaction, the less a loudspeaker becomes in its upper cutoff frequency be limited.