Impulse Response Measurement per AES-2id

TL;DR

AES-2id system alignment uses impulse response analysis to identify direct sound arrival time, early reflections, and the transition to the reverberant field. The impulse response reveals timing relationships that the transfer function magnitude alone cannot show. SonaVyx impulse response tool displays the time-domain waveform with markers for direct sound, first reflections, and the noise floor. This information drives delay alignment decisions for multi-source systems, subwoofer timing, and fill speaker integration. Understanding the impulse response is essential for making informed delay and polarity decisions during live sound system tuning.

IR in System Alignment

AES-2id practitioners use the impulse response for timing analysis. The IR shows when energy arrives at the measurement microphone and from which path. This is critical for multi-speaker system alignment.

Direct Sound Identification

The first significant peak in the IR is the direct sound arrival
Its arrival time gives the propagation delay from source to microphone
This delay value is used to set delay lines for fill speakers and delay towers
The magnitude of the direct peak indicates source level at the measurement position

Early Reflection Analysis

Reflections arriving within 20 ms of direct sound can improve clarity (Haas effect)
Reflections between 20-50 ms may cause coloration or echo perception
Late reflections beyond 50 ms contribute to reverberant decay
Strong discrete reflections indicate surfaces that may need treatment or speaker aiming adjustment

Multi-Source Alignment

When aligning multiple speakers, compare impulse responses from each source at the overlap zone. The goal is to align direct sound arrivals within 1 ms for coherent summation. SonaVyx delay finder automatically identifies the propagation delay for alignment.

Subwoofer Integration

The impulse response at the crossover frequency region reveals whether subwoofers and mains are time-aligned. Misalignment appears as a split or broadened impulse around the crossover frequency.

Common Mistakes

Not windowing the IR to isolate direct sound from reflections
Using the wrong reference point for delay calculations
Ignoring polarity (a negative first peak indicates inverted polarity)
Measuring too far from the speaker where reflections dominate

SonaVyx Tools

Use the SonaVyx IR tool with automatic direct sound detection. Set delay alignment with the transfer function delay finder. Verify polarity with the problem detector. Check levels with the SPL meter. Run the AI diagnostic for automated alignment recommendations. Follow the PA tuning workflow for guided alignment.

Subwoofer Phase War at the Amphitheater