The Bedrock SM50 combines IEC 61672-1 Class 2 sound level metering with STIPA speech intelligibility measurement capability per IEC 60268-16. It is a versatile instrument for PA system testing, general noise surveys, and applications where both sound level metering and STIPA are needed at a Class 2 accuracy level. The SM50 provides the ability to measure both background noise levels and speech intelligibility from a single instrument, without the need to carry two separate devices.
The SM50 is suitable for less demanding STIPA applications where Class 1 accuracy is not required by the applicable standard or project specification. For voice alarm commissioning work subject to EN 54-16, BS 5839-8, or ISO 7240-19, Class 1 is typically required — in which case the i9 (Class 1 STIPA) would be the appropriate choice. For general PA system quality checks, educational STIPA demonstrations, and non-regulatory STIPA assessments, the SM50 provides cost-effective capability.
The SM50 is compatible with both the BTB65 Talkbox and the BTB115 Advanced Talkbox for all STIPA measurement work.
The SM50 displays STIPA results immediately after measurement using the five-tier classification scale defined in IEC 60268-16: Bad (0.00–0.30), Poor (0.30–0.45), Fair (0.45–0.60), Good (0.60–0.75), and Excellent (0.75–1.00). For most voice alarm and PA applications, a minimum result of Fair (0.50 or above) is the accepted compliance threshold. Results should be recorded at all required listening positions and compared with the project specification or applicable standard requirements. Background noise level should also be measured at each position, as high background noise is a common cause of low STI values and may indicate a need to adjust the PA system's level or coverage.
Request a Quote · STIPA Measurement Guide · Compare All Products · Buying Guide