Sound Level Meter Fnirsi FDM01 — Digital Noise Decibel Meter, Measurement Range 30–130 dB

The FNIRSI FDM01 is a compact digital sound level meter that measures ambient noise in the range of 30–130 dB and simultaneously monitors temperature and humidity. It features a sensitive 6 mm condenser microphone, a 2.3" VA color display with backlight, and a rechargeable 600 mAh lithium battery charged via USB-C. The device offers MIN/AVG/MAX display modes, FAST and SLOW dynamic response settings, a light alarm for threshold exceedance, and a HOLD function for value locking. The FDM01 is intended for use in offices, construction sites, transport, production rooms and public spaces where straightforward noise monitoring is required.

Advantages

The FDM01 provides accurate measurements with ±1.5 dB accuracy (calibrated at 94 dB, 1 kHz) across a frequency range of 31.5 Hz–8.5 kHz using A-weighting to match human ear sensitivity. Its 6 mm nickel-plated condenser microphone with silicone seals ensures high sensitivity and fast response while reducing interference from sudden volume spikes. The 2.3-inch VA display and clear dynamic scale (1 division = 2 dB) make readings easy to interpret, and the rechargeable battery with USB-C charging removes the need for disposable batteries. Durable ABS housing, silicone buttons and a soft wind shield improve reliability in field and industrial conditions.

Suitable for

• Workplace noise checks and occupational hygiene assessments
• Construction site and renovation noise monitoring
• Measuring noise in production and industrial environments
• Assessing room acoustics and appliance noise at home
• Monitoring noise levels in public spaces and transport

Key specifications

• Measurement range: 30–130 dB
• Accuracy: ±1.5 dB (94 dB @ 1 kHz)
• Frequency range: 31.5 Hz–8.5 kHz
• Frequency weighting: A-weighting
• Dynamic characteristics: FAST (1 s) / SLOW (1.25 s)
• Microphone: 6 mm condenser microphone
• Display: 2.3" VA color, 4 digits, resolution 0.1 dB, update rate 2 times/sec
• Battery: Rechargeable 600 mAh Li-ion (3.7 V), charged via USB-C
• Operating conditions: 0°C–40°C, 10%–80% RH
• Storage conditions: -10°C–60°C, 10%–70% RH

How to use

Turn on the sound level meter and allow the microphone to stabilize for a short time before measurement. Select A-weighting and choose FAST or SLOW response depending on whether the situation requires rapid capture of changing levels (FAST) or a more stable averaged reading (SLOW). Point the microphone toward the noise source, keep the device steady, and observe MIN/AVG/MAX values as needed. Use the HOLD function to freeze a reading on the screen and enable the light alarm to notify when a preset threshold is exceeded. Recharge the internal battery using the supplied USB-C cable when low.

Recommendations

For repeatable results, measure at a consistent distance from the noise source and avoid placing the microphone too close to reflective surfaces. Use the SLOW mode for steady background noise and FAST mode for fluctuating or impulsive sounds. Store the device within the specified temperature and humidity ranges to maintain sensor accuracy.