Setting up a noise monitoring program for the workplace involves:

### Step 1: Planning and Preparation

- Identify Goals
-
- Resource Allocation
- Conduct preliminary noise survey to identify noisy areas and prioritize monitoring locations

### Equipment Selection and Calibration

#### General Guidelines
- Specify the types of sound level meters and dosimeters to use.
For example, Type 1 or 2 sound level meters meeting ANSI S1.4, and Type 2 dosimeters meeting ANSI S1.25.
- Consider using sound level meters capable of octave or third-octave band frequency analysis.
This allows evaluating noise controls and hearing protector attenuation at different frequencies.
- Use integrating-averaging sound level meters to monitor average noise levels over longer durations.
This helps in assessing **compliance with permissible exposure limits.**
- Use real-time analyzers along with dosimeters to capture noise level variations and peak exposures.
- Select dosimeters that can measure different noise metrics like Lavg, Lmax, Lpeak, dose, and TWA.
- Consider using **noise dose badges**, which are convenient for monitoring large worker groups.
- Use **tripods, windscreens, and calibrators** to ensure proper use of meters and dosimeters.
- Send sound level meters to accredited labs annually for calibration. Calibrate dosimeters before and after each use.
- Maintain calibration records including dates, methods, and results.
- Field-check meter functionality before and after measurements by using a calibrator.
- Ensure proper training for personnel on selection, use, calibration and maintenance of equipment.
- Deployment: Calibration, always verify batteries, microphone windscreens, etc. are in working condition

#### Sound level meters vs noise dosimeters

> Sound level meters are flexible instruments suitable for area surveys, while dosimeters specifically assess personal exposures over time. Proper selection and application is important.

| Feature | Sound Level Meter | Noise Dosimeter |
|-|-|-|
| Purpose | Measures sound levels at a location | Measures personal noise exposure |
| Placement | Stationary - mounted on tripod | Worn by individual |
| Typical Use | Area monitoring, equipment noise, community noise | Occupational noise exposure monitoring |
| Measured Data | Instantaneous sound levels, Leq, Lmax, Lmin | Noise dose, TWA, Lavg, Lpeak |
| Frequency Weighting | A, C, Z | A, C |
| Octave/Third-Octave Bands | Available on some models | Available on some models |
| Display | On device screen | Some models, or via software |
| Power | AC line power or batteries | Internal battery |
| Calibration | Before/after use via acoustic calibrator | Before/after each use |
| Microphone | Externally mounted | Internal near hearing zone |
| Cost | $100 to thousands | $200 to $1500 |
| Examples | Brüel & Kjær, Casella, Extech | Casella, 3M, Quest |

#### Glossary of Terms

Here is the table with more detailed descriptions added:

| Feature | Description | Sound Level Meter | Noise Dosimeter |
|-|-|-|-|
| Instantaneous sound levels | Measures sound pressure levels (SPL) in real-time, captures fluctuations| Yes | Some models provide real-time SPL data |
| Leq | Equivalent continuous A-weighted sound level that contains the same noise energy as the varying levels over a period | Yes | Some models calculate Leq |
| Lmax | Highest A-weighted sound level measured over a given period | Yes | Most models record Lmax |
| Lmin | Lowest A-weighted sound level measured over a given period | Yes | Some models record Lmin |
| Noise dose | Percentage of maximum permitted daily noise exposure, calculated from noise level and duration | No | Yes, main parameter measured |
| TWA | Time-weighted average noise level over 8 hours calculated from noise dose | No | Yes, calculated from dose |
| Lavg | Average of the noise level over the measurement period | Some models provide Lavg | Yes, equivalent to Leq |
| Lpeak | Highest instantaneous C-weighted peak sound pressure level | Some models capture Lpeak | Most models record Lpeak |
| Frequency weighting | Applies filters (A, C, Z) to emphasize certain frequencies | A, C, Z filters available | A and C filters available |
| Octave/Third-octave bands | Measures and analyzes noise levels at specific frequency bands | Available on some high-end models | Available on some models |

##### Narrative Explanation

Here is another explanation of the terms and equipment described above.

1. **Instantaneous Sound Levels**: This is like taking a snapshot of the loudness at any given moment. Imagine a sound meter that tells you how loud something is right now. Some devices, like a sound level meter, always show this. Noise dosimeters might show it too, but not all of them.
2. **Leq (Equivalent Continuous Sound Level)**: Think of this as an average loudness over time. It's like blending all the different loud and quiet moments during a period into one steady sound level. Both sound level meters and some noise dosimeters can calculate this.
3. **Lmax (Maximum Sound Level)**: This is the loudest point recorded during a period. Imagine the peak of a mountain – that's your Lmax. Most sound level meters and noise dosimeters keep track of this.
4. **Lmin (Minimum Sound Level)**: Opposite of Lmax, this is the quietest moment captured. It's like finding the lowest point in a valley. Again, both types of devices might record this, but not always.
5. **Noise Dose**: This tells you what percentage of the day's allowed noise someone has been exposed to. It's like filling up a bucket with water, where the water is the noise, and there's a limit to how much you can fill. Only noise dosimeters measure this.
6. **TWA (Time-Weighted Average)**: This is a bit like Leq, but specifically calculated for an 8-hour workday. It's an average that considers how long someone is exposed to different noise levels. This is a specialty of noise dosimeters.
7. **Lavg (Average Sound Level)**: Similar to Leq, this is an average sound level over time. Some sound level meters and noise dosimeters provide this information.
8. **Lpeak (Peak Sound Pressure Level)**: Imagine the very highest spike in loudness during a period, like the crack of a thunderbolt. Lpeak is that spike. It's measured in a way that captures these sudden, loud noises. Some sound level meters and most noise dosimeters can record this.
9. **Frequency Weighting**: This is about focusing on certain pitches or frequencies of sound, like tuning a radio to hear different stations. Different filters (A, C, Z) are used to emphasize different frequencies. Sound level meters often have all these filters, while noise dosimeters typically have A and C.
10. **Octave/Third-Octave Bands**: This is a more detailed analysis of sound, breaking it down into specific frequencies or pitches, much like looking at each musical note separately. Some high-end sound level meters and dosimeters can do this.

In summary:
- **Sound Level Meters** are like cameras capturing various aspects of sound at any given moment, providing a detailed view of the sound environment.
- **Noise Dosimeters** are more like a diary, recording the exposure to sound over time, crucial for understanding long-term exposure and its potential impacts.

#### Equipment
> The goal is to have **enough equipment redundancy** to be able to deploy meters and dosimeters at multiple locations simultaneously and have reserves as back up.
##### Sound Level Meters
- **3-4 Type 2 sound level meters**. This allows for simultaneous measurements **at different locations and backup units.**
- Options include:
- Casella CEL-63X
- Extech HD600.
##### Noise Dosimeters
- You would need dosimeters for monitoring personal exposure levels of employees.
- The number depends on the workforce size. As a rough estimate, for a medium-sized factory with ~100 workers, I would recommend **having 10-20 dosimeters**.
- Options include:
- The Casella dBadge2
- The 3M Edge eg5.
##### Software
- You would need at least **1 advanced data analysis** software
- Multiple licenses may be needed if more than one person analyzes data.
- Options include:
- Casella Insight software
- Brüel & Kjær 2250/2270 software
##### Calibrators
- At least 1 acoustic calibrator to field-calibrate the sound level meters and dosimeters
- Options include:
- Casella CEL-120
##### Additional Equipment
- ~10 tripods for mounting sound level meters
- ~20 windscreens for microphones
- Extra batteries to allow continuous measurements

#### Cost Estimates

##### Minimum Viable vs Ideal Plan

###### **Minimum Plan to Meet Guidelines**

Here's the information formatted as a table:

| Category | Items | Quantity and Price | Subtotal |
|----------|-------|--------------------|----------|
| **Sound Level Meters** | Extech HD600 | 2 x $200 each | $400 |
| | Calibrator: Quest QC-10 | 1 x $100 | $100 |
| | Tripods: AmazonBasics 60" | 2 x $30 each | $60 |
| | **Total** | | **$560** |
| **Noise Dosimeters** | Quest MIC440 | 10 x $300 each | $3,000 |
| | Calibrator: Quest QC-20 | 1 x $200 | $200 |
| | **Total** | | **$3,200** |
| **Software** | Casella Insight Data Management | 1 x $1,500 | $1,500 |
| **Accessories** | Windscreens: Windtech WS1 | 20 x $10 each | $200 |
| | Batteries: Powerex AA | 2 packs x $20 each | $40 |
| | **Total** | | **$240** |

###### **Total Minimum Viable Cost: $5,500**

**the ideal plan**

| Category | Items | Quantity and Price | Subtotal |
|----------|-------|--------------------|----------|
| **Sound Level Meters** | Casella CEL-63X | 3 x $800 each | $2,400 |
| | SKAN SK-6116 Octave Band Analyzer | 1 x $4,000 | $4,000 |
| | Calibrators: Casella CEL-120 | 2 x $300 each | $600 |
| | Tripods: K&M 210/9 | 4 x $60 each | $240 |
| | **Total** | | **$7,240** |
| **Noise Dosimeters** | 3M Edge Eg5 | 20 x $500 each | $10,000 |
| | Calibrators: Quest QC-20 | 3 x $200 each | $600 |
| | **Total** | | **$10,600** |
| **Software** | Brüel & Kjær 2250/2270 Analysis Software | 2 x $2,000 each | $4,000 |
| **Accessories** | Windscreens: Muzzle WS1 | 30 x $20 each | $600 |
| | Batteries: Powerex AA | 5 packs x $20 each | $100 |
| | **Total** | | **$700** |

**Total Above Average Cost: $22,540**

###### Key Benefits to Ideal Plan Explained
Here are some key benefits provided by the additional equipment included in the the ideal plan compared to the minimum plan. In summary, the ideal plan provides instrumentation with enhanced accuracy, more analysis features, and overall higher quality for complex monitoring. The investment upfront can pay off long-term with superior results.

- Casella CEL-63X Sound Level Meters:
- Higher accuracy as Type 1 meter versus Type 2 like Extech HD600
- Built-in octave band frequency analysis
- Larger measurement range and lower noise floor
- Back-lit display and more measurement parameters
- Higher precision and more flexibility for advanced surveys

- SKAN SK-6116 Octave Band Analyzer:
- Provides real-time octave band analysis
- Useful for detailed noise source identification
- Allows assessment of noise controls and hearing protector attenuation
- Not included in standard sound level meters

- Additional Casella CEL-120 Calibrators:
- Allows multiple calibration sets for different measurement teams
- Provides backup calibration source

- 3M Edge Eg5 Noise Dosimeters:
- Advanced data logging and analysis capabilities
- Lower noise floor and higher accuracy
- Wireless communication options
- Rechargeable batteries
- Better performance for low noise measurements

- Brüel & Kjær 2250/2270 Software:
- More advanced analysis and reporting capabilities
- Interface with sound level meters for downloaded data
- Useful tools for occupational and community noise monitoring
- Superior to standard software like Casella Insight

### Regulations

#### OSHA Noise Standard (29 CFR 1910.95)
> This regulates permissible noise exposure levels for workers in the USA.

Key elements:
- **Permissible Exposure Limit (PEL)**: 90 dBA for 8 hours
- **Action Level**: 85 dBA for 8 hours

At or above **Action Level**, a Hearing Conservation Program must be implemented that includes
- Noise monitoring
- Audiometric testing
- Hearing protection
- Training
- Recordkeeping

##### ACGIH Threshold Limit Values
> Recommended limits from the **American Conference of Governmental Industrial Hygienists**:
- 8-hour Time Weighted Average (TWA): 85 dBA
- Threshold Limit Value (TLV) Peak Sound Pressure: 140 dB

##### NIOSH
> Proposed limits by the National Institute for Occupational Safety and Health:
- Recommended Exposure Limit (REL): 85 dBA for 8 hours
- REL Peak Sound Pressure: 140 dB
- Buy Quiet Programs
- Initiatives encouraging purchase of quieter equipment < 85 dBA to prevent hazardous exposures.

There are also community noise regulations from EPA, FAA, HUD and state/local authorities, however we recommend prioritizing OSHA regulations as starting point.

#### Summary table

| Term | Description | Value | Calculation |
|-|-|-|-|
| Permissible Exposure Limit (PEL) | Maximum permitted 8-hour TWA noise exposure | 90 dBA | None, fixed value |
| Action Level | 8-hour TWA noise exposure that triggers requirements for hearing conservation program | 85 dBA | None, fixed value |
| TWA | Time-Weighted Average noise level over 8 hours | Varies | Calculated based on noise dosimetry data |
| Noise Dose | Percentage of permitted daily noise exposure | Varies | Calculated from sound levels and durations |
| Dose Calculation | Formula to calculate noise dose percentage | Dose% = 100 x (C1/T1 + C2/T2 + ... + Cn/Tn) | C = time duration at noise level, T = permitted time at that level |
| Permitted Dose | 100% per day | N/A | Set by OSHA |
| Exceedance | Noise exposure exceeding PEL or Action Level | Yes/No | Compare TWA or dose% to PEL/AL |

#### Action Levels

The 85 dBA Action Level specified in the OSHA noise regulation (29 CFR 1910.95) **applies to the noise exposure of individual workers, not general area noise levels**. Specifically:
- The 85 dBA is an 8-hour time-weighted average (TWA) noise exposure level.
- This TWA exposure is calculated for each worker based on the noise levels they are subjected to over the course of their work shift as well as the duration spent at each level.
- The TWA can be determined directly using a noise dosimeter worn by the worker. The dosimeter measures the cumulative noise dose the worker receives.
- The 85 dBA TWA threshold is then compared to each worker's measured exposure to determine if they exceed the Action Level.
- Area noise level measurements taken with a sound level meter are useful for characterizing noise sources and selecting hearing protection.** However, they do not indicate individual worker exposures needed to ascertain if the Action Level is exceeded.**
- Exceeding the 85 dBA Action Level for a worker triggers the requirement for the employer to implement a hearing conservation program, provide hearing protection, conduct annual audiometric testing, etc. specifically for that overexposed worker.