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What is Sound Pressure Level?

Sound Pressure Level (SPL) is a way of expressing sound in decibels, based on the pressure variations a sound wave creates in the air.

What is Sound Pressure Level (SPL)? SPL is a way of expressing sound in decibels, based on the pressure variations a sound wave creates in the air.

While sound pressure itself is measured in Pascals, SPL converts that into a logarithmic decibel scale, making it easier to compare very quiet and very loud sounds. The formula for SPL relates the measured pressure to a reference pressure of 20 micropascals — the threshold of human hearing.

This makes SPL the standard way of describing sound in everything from workplace assessments to product testing and environmental noise studies. In this video, we explain what SPL means, how Pascals convert into decibels, and why the logarithmic scale is so important in acoustics. Want to learn more about sound measurement terms?

Visit the AcSoft Knowledge Hub, full of FAQs, how-tos, and practical insight into noise and vibration monitoring.

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FAQ's

SPL is used in occupational and environmental noise regulations, including OSHA, EU Directive 2003/10/EC, ISO 1999, and local environmental noise ordinances to evaluate human noise exposure.

SPL is measured using calibrated sound level meters in accordance with standards such as IEC 61672 and ISO 9612, with defined measurement positions, time weightings, and averaging periods.

Sound Pressure Level must be monitored in industries where human exposure to noise is regulated, or where noise impacts public health, safety, or comfort. SPL is the primary metric used in laws and standards because it represents the sound level experienced at a specific location. These include Manufacturing and Industrial Operations, Construction and Infrastructure, Transportation (Road, Rail, Aviation), Environmental and Community Noise Management; and Entertainment and Event Venues.

Best products to monitor Sound Pressure Levels

At AcSoft, we supply a comprehensive range of noise measurement and monitoring instruments designed to support accurate, compliant noise pressure levels in your industry.

  • Noise Monitoring Stations — Rugged outdoor systems like the SV 307A provide long-term, continuous monitoring with certified MEMS microphones and integrated data logging for environmental noise projects.
  • Sound Level Meters & Analysers — Portable Class 1/2 sound level meters and multi-channel analysers (e.g., NoisePAD systems) enable real-time noise measurement with flexible frequency and time weighting options for workplace, construction, or R&D use.