Measuring Low-Frequency Noise & Infrasound: DIN 45680:1997 and the New DIN/TS 45610-1:2026-01
Measuring and evaluating low frequencies below 100 Hz has become increasingly critical due to the widespread installation of air-source heat pumps in residential areas, HVAC systems, CHP plants, and wind turbines. While capturing physical sound pressure down to the infrasound range (1 Hz to 20 Hz) is straightforward with precision hardware, evaluating human perception per German TA Lärm regulations requires specialized analysis.
Our PC measurement system Akulap supports both the legally binding DIN 45680:1997 and the new Technical Specification DIN/TS 45610-1:2026-01 released in January 2026 (representing the current state of the art). Measure live using our calibrated USB measurement microphones or import existing .wav recordings (including compressed ADPCM files from NTi XL2/XL3 or Svantek meters) for post-processing.
Akulap Sound + DIN 45680 Module + USB Mic (6533) + Calibrator
The turnkey package for engineering consultants and industry: Includes Akulap Sound Base (3303016), DIN 45680 / TS 45610 Module (3303061), USB Measurement Mic (6533), and closed-loop Center 326 Calibrator (7002).
With 1/2" Class 1 USB Mic (6510) & 125/250 Hz Calibrator (7003)
For official surveys requiring Class 1 precision and low-frequency verification: Pairs the modular 1/2" Class 1 USB mic ATD5-T (6510) with the Center 327 multi-frequency calibrator (7003, testing 125 Hz & 250 Hz).
Rent Complete USB Measurement Kit (#1202m Private/EDU or #1202RC Commercial)
Already have a Windows laptop and want to log a heat pump or low-frequency hum over 1–2 weeks? Rent our complete package (Private/EDU incl. calibrator or Commercial) with 100% purchase credit.
Why dB(A) Is Blind to Heat Pumps & Hum: LCeq − LAeq & 1/3-Octave Analysis
The A-weighting curve heavily attenuates low frequencies (-30.2 dB at 50 Hz, -50.5 dB at 20 Hz!), whereas C-weighting captures the true physical sound pressure. Select a typical low-frequency source below to inspect the LCeq − LAeq difference and the 8 Hz – 100 Hz third-octave spectrum:
Classic neighborhood conflict: A basic dB(A) meter shows a seemingly quiet 28.0 dB(A), yet inside the quiet bedroom the 63 Hz tone dominates at 54.5 dB(C) (LCeq − LAeq = 26.5 dB!). Both DIN 45680:1997 and DIN/TS 45610-1:2026-01 identify a significant low-frequency tonal immission.
🎧 Interactive WebAudio Demo: What Your Ear (dB(C)) Hears vs. What the dB(A) Filter Removes
Tiny smartphone or laptop speakers cannot physically reproduce low frequencies between 31.5 Hz and 63 Hz—you will hear nothing on them! Please use quality headphones or a HiFi system (ideally with a subwoofer) at moderate volume for this listening test.
Active: Unfiltered low-frequency sound (dB(C)). You hear the full 50/63 Hz compressor hum with subtle modulation as experienced inside a quiet bedroom.
DIN 45680:1997 vs. DIN/TS 45610-1:2026-01 (Draft 2020): What Changed?
German TA Lärm regulations reference DIN 45680 for indoor low-frequency noise. While the 1997 edition remains formally valid, the Technical Specification DIN/TS 45610-1:2026-01 published in January 2026 represents the current state of the art. Akulap Module #3303061 evaluates your measurement according to both standards with a single click:
| Criterion | DIN 45680:1997 (incl. Suppl. 1) | DIN/TS 45610-1:2026-01 (Draft 2020) |
|---|---|---|
| 1. Pre-Screening (LC − LA) | Rigid threshold: Evaluation only triggered if LCeq − LAeq > 20 dB. | Removed completely! All 1/3-octave bands are evaluated regardless of LC − LA difference. |
| 2. Mandatory Frequency Range | 10 Hz to 80 Hz (1/3-octave bands; 8 Hz and 100 Hz only in special cases). | Expanded to 8 Hz through 100 Hz (mandatory) for all measurements. |
| 3. Infrasound Range (1 Hz – 20 Hz) | Not defined below 8 Hz. | Additional informative evaluation range from 1 Hz to 20 Hz integrated. |
| 4. Hearing Threshold Principle | Rigid comparison against individual band hearing thresholds; sub-threshold bands were discarded. | Energetic summation across all weighted 1/3-octave bands without premature threshold truncation. |
| 5. Spectral & Temporal Penalties | Simple binary distinction between tonal (+5 dB above neighbors) and non-tonal. | Objective algorithmic calculation of penalties for tonality and temporal fluctuation / impulsiveness. |
Why Low-Frequency Noise (< 100 Hz) in Bedrooms Is So Difficult to Mitigate
1. The Bedroom Masking Paradox
Bedrooms contain mattresses, curtains, and carpets that absorb mid and high frequencies effectively while having zero effect below 100 Hz (wavelength > 3.4 m). Without ambient high-frequency masking, a heat pump's low-frequency hum stands out starkly at night.
2. Windows & Thermal Insulation Pass Low Bass
While massive masonry blocks low frequencies through sheer mass, modern multi-pane windows and lightweight roof structures often exhibit resonance dips between 30 Hz and 80 Hz, transmitting low-frequency hum indoors.
3. Direct Import of NTi XL2 / XL3 & Svantek WAV Files
Already own an NTi XL2, NTi XL3, or Svantek handheld meter? Akulap directly imports recorded .wav files (including standard compressed 24 kHz ADPCM files from the NTi XL2!) along with calibration headers to generate complete DIN 45680 / TS 45610-1 reports.
Configurator: Your Measurement System for DIN 45680 & DIN/TS 45610-1:2026-01
Assemble your complete system from Akulap Base, DIN 45680 Module, USB Measurement Microphone, and Calibrator – or choose the matching 1-week rental package for your own laptop below:
1. Akulap Base Software & Low-Frequency Modules
Mandatory Base & DIN 45680 Core Module2. Select Akulap USB Measurement Microphone (Class 2 vs. Class 1)
3. Select Sound Level Calibrator (1000 Hz Standard vs. 125/250 Hz Low-Frequency)
Your DIN 45680 Configuration
Rent a Complete USB Measurement System for Low-Frequency & Environmental Noise (For Your Windows Laptop)
Already own a Windows laptop? Rent our preconfigured complete kit consisting of a calibrated USB measurement microphone and Akulap analysis software (including DIN 45680 / DIN/TS 45610-1). Choose between our non-commercial / EDU rate (calibrator included) and our commercial B2B rental package:
EDU & Private Rental Kit: Complete USB Audio Measurement System (#1202m)
Designed for private individuals (e.g. neighborhood noise from air-source heat pumps or HVAC), universities, and non-commercial projects. The sound level calibrator is already included in this package!
- ✓ High-precision USB measurement microphone + Akulap software (incl. DIN 45680 / TS 45610-1)
- ✓ Includes sound level calibrator for immediate level-accurate measurements
- ✓ Continuous .wav chain logging on your own Windows PC/laptop
- ✓ 100% rental credit towards subsequent purchase
Commercial Rental Kit: Complete USB Audio Measurement System (#1202RC)
For engineering offices, acoustic consultants, and industry conducting compliant environmental, wind turbine, and low-frequency noise surveys per TA Lärm / DIN 45680.
- ✓ Calibrated USB measurement microphone + Akulap software (incl. DIN 45680 / TS 45610-1)
- ✓ Full commercial license for official surveys & industrial diagnostics
- ✓ 100% rental credit towards subsequent system purchase
Video Tutorials: A/C Weighting at Low Frequencies & WAV File Import
Why dB(A) Filters Out Low Bass and How dB(C) − dB(A) Reveals Low-Frequency Hum
Mathematically exact real-time simulation from our Python DSP engine: See and hear how sharply the A-curve rolls off below 100 Hz while the C-curve preserves physical sound pressure.
Clicking loads the video via youtube-nocookie.com (GDPR 2-click protection).
Importing Recorded .wav Files (e.g. from NTi XL2) into Akulap for DIN 45680 Evaluation
Learn how to load long-term audio recordings into Akulap, automatically parse embedded calibration headers, and select low-frequency intervals with your mouse.
Clicking loads the video via youtube-nocookie.com (GDPR 2-click protection).
FAQ on DIN 45680, DIN/TS 45610-1:2026-01 & Heat Pump Measurements
Which standard applies in 2026 for low-frequency noise: DIN 45680:1997 or DIN/TS 45610-1:2026-01? ▼
Legally, German TA Lärm regulations still reference DIN 45680:1997. However, since January 2026 the new Technical Specification DIN/TS 45610-1:2026-01 (technically matching Draft DIN 45680:2020) represents the recognized state of the art (8–100 Hz mandatory, 1–20 Hz informative, without the old 20 dB pre-screening filter). Akulap Module #3303061 evaluates both standards side by side.
What is the difference between the private/EDU rental package (#1202m) and the commercial rental package (#1202RC)? ▼
Both rental kits include the calibrated USB measurement microphone and Akulap software (incl. DIN 45680 / DIN/TS 45610-1) for your own Windows laptop. Package #1202m is a discounted rate for private individuals, citizen initiatives, and educational institutions that already includes the sound level calibrator. Commercial package #1202RC is licensed for engineering consultants and industrial users, allowing you to optionally add the Center 326 rental calibrator (#20002) if you do not already own a 1/2" calibrator.
Are compressed ADPCM WAV files from an NTi XL2 or XL3 sufficient for DIN 45680 analysis? ▼
Yes! In their base configuration, the NTi XL2 and XL3 record compressed 4-bit ADPCM WAV files at a 24 kHz sample rate (12 kHz bandwidth). Because DIN 45680 and DIN/TS 45610-1 evaluate frequencies up to 100 Hz, this bandwidth is completely sufficient. Akulap natively reads NTi ADPCM files and their embedded calibration headers.