HS5661+ Precision Sound Level Meter

Overview

The HS5661+ Precision Sound Level Meter is a compact, Class 1-compliant instrument engineered for high-fidelity acoustic measurements in industrial, environmental, occupational health, and research applications. Designed in accordance with the international metrological standard IEC 61672-1:2013 and its national counterpart GB/T 3785.1–2010, the HS5661+ delivers traceable, repeatable sound pressure level (SPL) data across a broad dynamic range. Its core measurement architecture employs a precision 1/2″ condenser microphone with integrated preamplifier, coupled with digital true RMS detection—ensuring accurate quantification of both steady-state and impulsive noise events, even under rapidly varying acoustic conditions. Unlike lower-class instruments, the HS5661+ maintains strict spectral and temporal fidelity through certified A- and C-frequency weightings and selectable Fast (F) and Slow (S) time constants—enabling compliance with occupational exposure limit assessments (e.g., OSHA 1910.95, ISO 9612), environmental noise mapping (ISO 1996 series), and product noise labeling requirements (e.g., EU Directive 2000/14/EC).

Key Features

• Class 1 accuracy per IEC 61672-1:2013 and GB/T 3785.1–2010—validated for legal metrology and regulatory reporting
• True RMS detector with peak factor ≥10—capable of resolving transient peaks without clipping, critical for impact noise and machinery diagnostics
• Four manually selected linear measurement ranges (25–80 dB to 80–140 dB re 20 µPa), each offering >60 dB usable dynamic span
• Integrated analog-style bar graph display alongside numeric LCD—providing real-time visual feedback aligned with human auditory response
• Dual output capability: analog AC output for oscilloscope or spectrum analyzer integration, and RS-232 serial interface for automated data logging and remote control
• Rugged ABS polymer housing rated IP54—resistant to dust ingress and water splashes during field deployment
• Low-power design enabling 24-hour continuous operation on standard AA alkaline cells; optional 6 V DC external supply for extended stationary use

Sample Compatibility & Compliance

The HS5661+ is optimized for airborne sound pressure measurements in air at ambient temperatures (–10 °C to +50 °C) and standard atmospheric pressure. It accepts industry-standard 1/2″ Class 1 microphones and is fully compatible with traceable calibration sources—including 94 dB and 114 dB Class 1 pistonphones and acoustic calibrators operating at 1 kHz. The instrument supports periodic verification and adjustment per ISO/IEC 17025-accredited laboratory procedures. Its metrological traceability path aligns with national standards bodies (e.g., CNAS in China, UKAS in the UK, DAkkS in Germany). While not intrinsically safe, its non-explosive construction makes it suitable for general factory floors, urban noise surveys, transportation corridors, and educational laboratories—not for hazardous area deployment without additional certification.

Software & Data Management

Through its RS-232 interface, the HS5661+ integrates seamlessly with PC-based acquisition software for time-synchronized multi-channel monitoring, statistical analysis (L_eq, L_max, L_min, L_n percentiles), and report generation compliant with ISO 1996-2 and ISO 532-1. Raw data streams include timestamped SPL values, weighting mode, time constant, and active range—supporting audit-ready documentation. The device does not embed internal storage or cloud connectivity; however, its ASCII-formatted serial protocol enables compatibility with LabVIEW, MATLAB, Python (pySerial), and custom SCADA systems. All firmware and configuration parameters are retained during battery replacement, preserving calibration state integrity between sessions.

Applications

• Occupational noise assessment per ISO 9612 and national OEL frameworks (e.g., ACGIH TLVs®, EU Physical Agents (Noise) Directive)
• Environmental noise monitoring near roadways, railways, airports, and industrial boundaries in accordance with ISO 1996-1 and local municipal ordinances
• Product noise testing for appliances, power tools, HVAC equipment, and automotive components against ISO 3744, ISO 3746, or SAE J1211
• Acoustic teaching labs—supporting experiments in wave propagation, frequency analysis, and hearing conservation education
• Pre-compliance screening prior to formal third-party type testing or certification (e.g., CE marking, ENERGY STAR)

FAQ

Does the HS5661+ meet international Class 1 requirements for legal metrology?

Yes—it conforms fully to IEC 61672-1:2013 Edition 3.0 and GB/T 3785.1–2010, satisfying the performance criteria required for regulatory enforcement and court-admissible noise evidence.
Can it measure impulse or impact noise accurately?

Yes—the true RMS detector with peak factor ≥10 and Fast (F) time weighting ensures faithful capture of short-duration transients such as hammer blows, sheet metal stamping, or firearm discharges.
Is calibration traceable to national standards?

Yes—when calibrated using a Class 1 acoustic calibrator (e.g., Brüel & Kjær 4231 or GRAS 46AG), results are traceable to NIM (China), NIST (USA), or PTB (Germany) via accredited calibration laboratories.
What is the expected battery life under continuous use?

Approximately 24 hours with fresh alkaline AA cells at 23 °C and typical measurement load; battery status is indicated on-screen prior to critical depletion.
Does the RS-232 interface support real-time streaming at high sampling rates?

It transmits instantaneous SPL values at up to 2 Hz update rate—sufficient for L_eq integration and percentile statistics, but not for raw waveform capture (which requires dedicated digital audio interfaces).