--- title: "Cirrus Research Noise Monitors | Aethair" description: "Cirrus Research Optimus and Optimus+ sound level meters in the Aethair sensor catalog: 20 Class 1 and 2 models for SPL, Leq, Peak, and Ln via Thiamis." url: https://aethair.io/sensors/cirrus-research-noise-monitors/ --- Sensors · Noise Monitors # Cirrus Research Noise Monitors Cirrus Research Optimus and Optimus+ handheld sound level meters are integrating, data-logging instruments that measure SPL, Leq, Peak, and statistical Ln to IEC 61672 Class 1 or Class 2. The environmental models add real-time 1/1 and 1/3 octave-band analysis. The 15x, 16x, and 17x families are the basic, occupational, and environmental tiers, and the third digit sets the class (1 is Class 2, 2 is Class 1). [Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Build a Configuration](https://aethair.io/build/?params=sound_spl,sound_leq,sound_lpeak,sound_ln) At a glance **4** parameters **20** models [**Connects via Thiamis** RS-232 · ASCII](https://aethair.io/products/thiamis/) 2 standards limit what it measures - [OSHA / NIOSH noise Occupational Noise Exposure (OSHA / NIOSH)](https://aethair.io/standards/occupational_noise/) - [WHO noise 2018 WHO Environmental Noise Guidelines for the European Region (2018)](https://aethair.io/standards/who_noise_2018/) Measures ## What Cirrus Research Noise Monitors Measure 4 parameters, each linked to its page: the sensors, units, and standards behind it. [Sound Pressure Level (SPL) dB](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq) dB 1/1 octave, 1/3 octave](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak) dB](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln) dB](https://aethair.io/parameters/sound_ln/) [Connects via **Thiamis**](https://aethair.io/products/thiamis/) Wired interface [RS-232 ASCII](https://aethair.io/products/thiamis/#port-rs232) Models ## Cirrus Research Noise Monitors Models 20 models, each with what it measures and the ranges its datasheet gives. | Model | Description | Measures & specs | | - | - | - | | **151B** | Optimus+ Industrial (Red) Class 2 sound level meter: sound pressure level with A/C/Z weightings and Max/Min; SPL only, no Leq or octave bands. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) | | **152B** | Optimus+ Industrial (Red) Class 1 sound level meter: sound pressure level with A/C/Z weightings and Max/Min; SPL only, no Leq or octave bands. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) | | **151A** | Previous-generation Optimus Class 2 sound level meter (SPL only); superseded by the 151B. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) | | **152A** | Previous-generation Optimus Class 1 sound level meter (SPL only); superseded by the 152B. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) | | **161B** | Optimus+ Industrial (Red) Class 2 occupational sound level meter that adds integrating Leq and Peak (with on-device TWA / dose); no octave bands. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | | **162B** | Optimus+ Industrial (Red) Class 1 occupational sound level meter that adds integrating Leq and Peak (with on-device TWA / dose); no octave bands. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | | **161C** | Optimus+ Industrial (Red) Class 2 occupational sound level meter with real-time 1/1 octave bands and NR/NC curves; SPL, Leq, and Peak. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq) 1/1 octave](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | | **162C** | Optimus+ Industrial (Red) Class 1 occupational sound level meter with real-time 1/1 octave bands and NR/NC curves; SPL, Leq, and Peak. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq) 1/1 octave](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | | **161A** | Previous-generation Optimus Red Class 2 occupational meter (SPL, Leq, Peak); superseded by the 161B. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | | **162A** | Previous-generation Optimus Red Class 1 occupational meter (SPL, Leq, Peak); superseded by the 162B. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | | **161D** | Previous-generation Optimus Red Class 2 occupational meter (SPL, Leq, Peak); no longer in the current Cirrus catalog. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | | **162D** | Previous-generation Optimus Red Class 1 occupational meter (SPL, Leq, Peak); no longer in the current Cirrus catalog. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) | | **1710** | Optimus+ Environmental (Green) Class 2 sound level meter: SPL, Leq, Peak, and statistical Ln (e.g. L10, L90). Base model, without octave bands. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) | | **1720** | Optimus+ Environmental (Green) Class 1 sound level meter: SPL, Leq, Peak, and statistical Ln (e.g. L10, L90). Base model, without octave bands. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) | | **171A** | Optimus+ Environmental (Green) Class 2 environmental sound level meter with real-time 1/1 octave bands and NR/NC curves; SPL, Leq, Peak, and statistical Ln. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq) 1/1 octave](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) | | **172A** | Optimus+ Environmental (Green) Class 1 environmental sound level meter with real-time 1/1 octave bands and NR/NC curves; SPL, Leq, Peak, and statistical Ln. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq) 1/1 octave](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) | | **171C** | Optimus+ Environmental (Green) Class 2 sound level meter; the top tier adds real-time 1/1 and 1/3 octave bands, tonal-noise detection, and up to 28 statistical Ln values. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq) 1/1 octave, 1/3 octave](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) | | **172C** | Optimus+ Environmental (Green) Class 1 sound level meter; the top tier adds real-time 1/1 and 1/3 octave bands, tonal-noise detection, and up to 28 statistical Ln values. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq) 1/1 octave, 1/3 octave](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) | | **171B** | Previous-generation Optimus Green Class 2 environmental meter (SPL, Leq, Peak, Ln); superseded by the 171C. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) | | **172B** | Previous-generation Optimus Green Class 1 environmental meter (SPL, Leq, Peak, Ln); superseded by the 172C. | [Sound Pressure Level (SPL)](https://aethair.io/parameters/sound_spl/) [Equivalent Continuous Level (Leq)](https://aethair.io/parameters/sound_leq/) [Peak Level (Lpeak)](https://aethair.io/parameters/sound_lpeak/) [Statistical Level (Ln)](https://aethair.io/parameters/sound_ln/) | Standards ## Standards for What It Measures Standards that set limits on the parameters it reports, plus any method standard the instrument is built to. [OSHA / NIOSH noise Occupational Noise Exposure (OSHA / NIOSH) 1 of its parameters](https://aethair.io/standards/occupational_noise/) [WHO noise 2018 WHO Environmental Noise Guidelines for the European Region (2018) 1 of its parameters](https://aethair.io/standards/who_noise_2018/) Built to [IEC 61672: sound level meters (Class 1/2)](https://aethair.io/standards/iec_61672/) Solutions ## Where Cirrus Research Noise Monitors Are Used Solutions whose recommended configuration uses this instrument or whose standards it is built to, followed by solutions whose core panel it partly measures. ### [Noise Monitoring](https://aethair.io/solutions/noise/) Environmental and occupational sound levels On the platform ## What Cirrus Research Noise Monitors Get From Aethair Connected through Thiamis, its readings arrive in the same Environet account as Aethair's own monitors. ### [Live data and alerts](https://aethair.io/platform/environet/) [Environet](https://aethair.io/platform/environet/) shows the instrument live and alerts the people you choose by email, SMS, and webhook, at the thresholds you set. [Noesis](https://aethair.io/platform/noesis/) sets up a dashboard, a report, or an alert from a plain-text request. ### [Compliance reports](https://aethair.io/platform/reports/) [Aethair Reports](https://aethair.io/platform/reports/) produces scheduled or on-demand reports from the instrument's readings, as a PDF or secure link. Templates cover Aethair Blue, WELL v2, cabin air (ISO 23875), and the CMS-2567 healthcare codebook (ASHRAE 170), or you can report against custom limits such as OSHA PELs, NAAQS, EPA guidance, or your own program limits. ### [Dashboards and the app](https://aethair.io/platform/dashboards/) Environet dashboards and the [Aethair App](https://aethair.io/platform/app/) show the instrument's readings just like any Aethair device. The occupant-facing [Aethair Dashboards](https://aethair.io/platform/dashboards/) status display is built around Aethair IAQ and Aethair PRO. Similar ## Other Noise Monitors ### [TSI](https://aethair.io/sensors/tsi-noise-monitors/) [Noise Monitors](https://aethair.io/sensors/tsi-noise-monitors/) [TSI Quest SoundPro SE/DL Class 1 and Class 2 integrating sound level meters and real-time analyzers…](https://aethair.io/sensors/tsi-noise-monitors/) Questions ## Cirrus Research Noise Monitors FAQ What do the Cirrus Optimus model numbers mean? The family digits set the tier: 15x is the basic sound level meter (SPL only), 16x the occupational / industrial meter (adds Leq, Peak, and integrating TWA / dose), and 17x the environmental meter (adds statistical Ln such as L10 and L90). The final digit is the IEC 61672 class: a code ending in 1 (e.g. 161, 171, 1710) is Class 2 and one ending in 2 (e.g. 162, 172, 1720) is Class 1. A trailing letter marks the feature tier: A adds real-time 1/1 octave bands, C adds 1/1 and 1/3 octave bands with tonal-noise detection. Which Optimus noise metrics does the integration read? The broadband levels: sound pressure level (LAF/LAS/LAI and LCF/LCS/LCI: A/C/Z weightings in Fast, Slow, and Impulse), equivalent continuous level Leq (LAeq/LCeq/LZeq), peak level (LApeak/LCpeak/LZpeak), and, on the 17x environmental models, the statistical level L90. The basic 15x meters report SPL only; the 16x and 17x models add Leq and Peak. The Optimus measures 1/1 and 1/3 octave bands. Are those brought into the platform? Not by default. The 171A/172A and the Red 161C/162C add real-time 1/1 octave bands, and the 171C/172C environmental models add 1/3 octave bands with tonal-noise detection. The integration reads the broadband A/C/Z levels (SPL, Leq, Peak, Ln) rather than the per-band octave spectra, which the meter also stores for download in Cirrus NoiseTools. Octave-band data is exposed by the meter's interface (10 bands for 1/1 octave, 31.5 Hz–16 kHz; 36 for 1/3 octave, 6.3 Hz–20 kHz) and can be enabled where a deployment needs it. How does the Optimus connect to the logger? Over a serial link at 115200 baud. The logger runs an identify (IDN) handshake to read the meter's model code and serial number, then polls it for the live noise levels at the logging interval. Class 1 meters use the MK:224 microphone, Class 2 meters the MK:216. Sources: [cirrusresearch.com](https://cirrusresearch.com/optimus-sound-level-meters/) · [cirrusresearch.com](https://cirrusresearch.com/product/environmental-sound-level-meter/) · [cirrusresearch.com](https://cirrusresearch.com/product/industrial-sound-level-meter/) · [cirrusresearch.com](https://cirrusresearch.com/wp-content/uploads/2023/02/Optimus-Green-Datasheet-English.pdf) · [cirrusresearch.com](https://cirrusresearch.com/wp-content/uploads/2023/03/Optimus-Red-Datasheet-English.pdf)