Choosing the right sound level meter depends on your measurement application, the standards you need to comply with, the capabilities you require today, and the ones you may need in the future. The wrong choice means either paying for capabilities you don't need, or purchasing additional modules later at significant extra cost. This guide explains the key differences between instrument classes, measurement capabilities, and standards to help you select the ideal acoustic measurement instrument.
The most important advice we can give: think ahead. Most acoustic measurement professionals find that their requirements expand over time. An environmental consultant who today only needs basic sound level metering may find that tomorrow's projects require STIPA, octave analysis, or reverberation time. With Bedrock Elite instruments, all capabilities are included from the start — no need to purchase additional modules when your requirements change.
Class 1 instruments meet IEC 61672-1 Class 1 requirements with tighter measurement tolerances (typically ±1.1 dB across the full frequency range). Class 1 is required for: regulatory noise measurements submitted to authorities, environmental noise assessments that may be subject to legal challenge, building acoustics measurements per ISO 16283, and most professional acoustic consultancy work. The Bedrock Elite i10 and i9 are IEC 61672-1 Class 1 instruments.
Class 2 instruments meet IEC 61672-1 Class 2 requirements with slightly wider tolerances (typically ±1.4 dB). Class 2 is suitable for: general-purpose noise surveys where regulatory defensibility is not critical, screening assessments to determine whether further Class 1 measurement is needed, STIPA commissioning work, basic occupational safety monitoring, and educational or training applications. The Bedrock Elite i5, SM50, and SM30 are Class 2 instruments.
If you commission, test, or maintain voice alarm systems, public address systems, or PA/GA systems, you need a STIPA-capable instrument. STIPA measurement per IEC 60268-16 is required by EN 54-16, BS 5839-8, ISO 7240-19, IEC 60849, and EN 50849. It is also increasingly specified in project documents for railway, airport, and industrial PA systems. Consider also whether you need Full STI — for life-safety critical applications, Full STI provides greater accuracy than STIPA, particularly in systems with distortion or complex acoustic environments.
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