Speech interference level

Speech Interference Level (SIL) is an acoustical parameter calculated from sound pressure levels measured in octave bands. It is used to characterize a noise signal in the frequency range where the human ear has its highest sensitivity.^[1]

The Speech Interference Level is calculated as the arithmetic mean of unweighted sound pressure levels in three or four octave bands in the 500 Hz - 4 kHz frequency range.^[2]

Variants of Speech Interference Level^[3]
PSIL	Arithmetic mean of 500 Hz, 1 kHz, and 2 kHz octave bands
SIL3	Arithmetic mean of 1 kHz, 2 kHz, and 4 kHz octave bands
SIL4	Arithmetic mean of 500 Hz, 1 kHz, 2 kHz, and 4 kHz octave bands

References

↑ Karl D. Kryter (2023). The Handbook of Hearing and the Effects of Noise: Physiology, Psychology, and Public Health. Leiden, Netherlands: Brill Publishers. ISBN 9789004653443.
↑ Criteria for Evaluating Room Noise (standard). Melville, New York: American National Standards Institute. 2008. ANSI S12.2-2008.
↑ Acoustics — Description, measurement and assessment of environmental noise — Part 1: Basic quantities and assessment procedures (standard). Geneva, Switzerland: International Organization for Standardization. 2016. ISO 1996-1:2016. Retrieved 21 March 2026.

External links

Speech Interference Levels in Aircraft Interior Noise Measurement
Sound Metrics: Speech Interference Level, Siemens Knowledge article (2019)

[1] Karl D. Kryter (2023). The Handbook of Hearing and the Effects of Noise: Physiology, Psychology, and Public Health. Leiden, Netherlands: Brill Publishers. ISBN 9789004653443.

[2] Criteria for Evaluating Room Noise (standard). Melville, New York: American National Standards Institute. 2008. ANSI S12.2-2008.

[3] Acoustics — Description, measurement and assessment of environmental noise — Part 1: Basic quantities and assessment procedures (standard). Geneva, Switzerland: International Organization for Standardization. 2016. ISO 1996-1:2016. Retrieved 21 March 2026.

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