The NL1 uses eight microphones arranged in a compact 3D geometry. From these, 12 sound intensity probes are formed with a spacer of 2 cm, allowing good resolution from 63 octave band up to 4 kHz octave band.
Sound intensity describes the direction of acoustic energy flow. By evaluating the resulting intensity vectors, the NL1 determines:
- Azimuth (horizontal direction, referenced to North)
- Elevation (vertical angle, referenced to the horizontal)
Analysis is performed in octave bands from 63 Hz to 4 kHz and in A frequency weighted.
Measurement Validity
Real-world sound fields are often influenced by reflections and multiple sources. Therefore, every NL1 measurement includes a quality indicator (Q).
- Low Q values indicate favorable conditions with a dominant source
- High Q values indicate diffuse or reactive sound fields
Only measurements meeting the quality criterion provide valid directional information. This enables automatic filtering and defensible results in post-processing.
Installation Guidance
For best results:
- Avoid nearby reflective surfaces (recommended distance ≥ 5 m)
- Install at sufficient height to reduce ground reflections
- Position the sensor between relevant sources where possible