Industrial Noise Survey & Assessment for Southern California Facilities
If your floor is loud enough that employees raise their voice to be heard, noise exposure is a regulated hazard, not just a nuisance — governed at both the state and federal level. Plaid Safety conducts on-site noise surveys and dosimetry for manufacturing, metal fabrication, machine shops, plating and finishing operations, and other high-noise industrial facilities, calculates 8-hour time-weighted averages, and builds the hearing conservation program and source control plan your facility actually needs.
Schedule a Noise Surveythe action level (8-hour TWA) that triggers a mandatory Hearing Conservation Program under Cal/OSHA and federal OSHA.
the Permissible Exposure Limit (PEL) that requires a documented evaluation of engineering and administrative controls.
the peak sound pressure ceiling for impulsive or impact noise — a single gunshot-like event can exceed it instantly.
Facilities That Typically Need a Noise Survey
Noise exposure risk isn't evenly distributed. It concentrates in specific processes and equipment types — if any of these describe your operation, a survey is worth doing before an inspection or a hearing complaint forces the question.
Common High-Noise Operations
- Metal fabrication, stamping, and sheet metal work
- Machine shops and CNC operations
- Plating, finishing, and surface treatment lines
- Plastics and injection molding
- Packaging and print production floors
- Warehousing and distribution with heavy material-handling equipment
- Any facility running compressors, generators, or pneumatic tools continuously
Signs Your Facility May Already Be Non-Compliant
- Employees have to raise their voice to be heard at arm's length
- Workers report ringing in their ears at the end of a shift
- You've never measured noise levels, only relied on equipment spec sheets
- You run 10- or 12-hour shifts and assumed 85 dBA compliance is automatically sufficient
- New equipment or a process change has been added since your last (or only) assessment
Why a Manufacturer's Spec Sheet Isn't Enough
Equipment noise ratings describe a machine in isolation. Your workplace is not a lab.
Real conditions differ from the spec sheet
Installation, maintenance condition, surrounding equipment, and room acoustics all change actual noise levels. A professional survey measures what's really happening on your floor, not what a catalog says a machine should produce.
Exposure is cumulative, not just peak volume
Compliance is based on an 8-hour time-weighted average, not a single loud moment. An employee moving between a quiet task and a loud one all shift can still exceed the action level even if no single reading feels extreme.
Extended shifts change the math
Facilities running 10- or 12-hour shifts often assume 85 dBA compliance is sufficient without adjusting for shift length. Longer shifts lower the exposure level at which the same cumulative dose is reached.
Hearing protection alone isn't a program
Handing out earplugs without monitoring, audiometric testing, training, and a documented evaluation of feasible controls does not satisfy the standard. A compliant program has several required components working together.
Your Noise Survey Feeds a Larger Requirement: the PPE Hazard Assessment
Handing out earplugs isn't the same as documenting that they're the right earplugs. Both Cal/OSHA and federal OSHA require a written PPE hazard assessment, and noise is one hazard it has to address.
Under 8 CCR §3380 (and the federal equivalent, 29 CFR §1910.132), employers must conduct and document a workplace hazard assessment to determine what PPE is actually required for each job task — noise is one category alongside eye, hand, respiratory, and fall protection. For hearing protection specifically, that means the Noise Reduction Rating (NRR) on the devices you provide has to be matched against your measured exposure levels, not selected off a shelf. Overprotecting isolates employees from warning signals and coworker communication; underprotecting leaves the exposure unmanaged. A noise survey gives you the actual numbers the hazard assessment is supposed to be based on — without it, the PPE selection is a guess, not a documented determination.
Plaid Safety can fold your hearing protection determination into a broader PPE hazard assessment covering every task and hazard category at your facility, not noise alone — so one site visit satisfies more than one regulatory requirement.
Source Control: The Preferred First Response
Once exposure reaches the 90 dBA PEL, Cal/OSHA and federal OSHA both require a documented evaluation of engineering and administrative controls before hearing protection is treated as the primary solution. Source control comes first for a reason: it reduces exposure for everyone in the space, not just the one person wearing protection correctly.
Engineering controls at the source
Equipment substitution, isolation, vibration damping, mufflers, enclosures, and routine maintenance that keeps machinery from generating excess noise in the first place. This is where a survey earns its value — identifying which specific source is driving the exposure.
Controlling how noise travels
Acoustic barriers, sound-absorbing materials, distance, and facility layout changes that reduce how much noise reaches an employee's work area, even when the source itself can't be fully quieted.
Limiting exposure time
Job rotation, scheduling, and work practice changes that reduce how long any individual employee spends in a high-noise area during a shift.
Hearing protection devices
Required whenever exposure remains at or above the action level after feasible controls are applied — but PPE depends on correct fit, consistent use, and proper attenuation, and protects only the individual wearing it.
Cal/OSHA and Federal OSHA: Related, Not Identical
California employers are governed by Cal/OSHA's noise standard, not the federal one — and the two aren't interchangeable.
Cal/OSHA
8 CCR §§5095–5100- Action level: 85 dBA, 8-hour TWA
- PEL: 90 dBA, 8-hour TWA
- Impulsive/impact noise ceiling: 140 dB peak
- Requires posting a copy of the noise regulation in the workplace — a requirement with no federal equivalent
- Baseline audiogram within 6 months of first exposure (12 months if mobile testing is used, with hearing protection provided in the interim)
Federal OSHA
29 CFR §1910.95- Action level: 85 dBA, 8-hour TWA
- PEL: 90 dBA, 8-hour TWA
- Similar hearing conservation program structure
- No standalone workplace posting requirement for the noise regulation itself
- Applies outside California and to certain federally regulated operations
NIOSH Sets a Stricter Bar Than the Legal Minimum
Compliance and genuine hearing protection aren't always the same number. NIOSH is worth understanding even though it doesn't issue citations.
The National Institute for Occupational Safety and Health (NIOSH) is a federal research agency, not an enforcement agency — it doesn't inspect facilities or issue citations the way Cal/OSHA and federal OSHA do. But NIOSH sets its own Recommended Exposure Limit (REL) for noise at 85 dBA as an 8-hour TWA, using a 3 dB exchange rate rather than OSHA's 5 dB exchange rate. That difference sounds small and isn't: under NIOSH's 3 dB rate, every 3 dB increase in noise level cuts the "safe" exposure time in half, versus every 5 dB under OSHA's rate. In practice, that makes NIOSH's standard meaningfully more protective at higher noise levels, even though the headline number — 85 dBA — matches Cal/OSHA and federal OSHA's action level.
For employers, this means a facility can be fully compliant with the legal standard and still be operating above what NIOSH considers genuinely protective of hearing over a career. Plaid Safety reports both figures where relevant, so you can see the difference between "compliant" and "how NIOSH would evaluate the same data" — and decide whether closing that gap with additional source control is worth it for your workforce, not just your inspection risk.
Noise Surveys and Hearing Conservation: Common Questions
What employers most often ask once they realize noise exposure is a regulated hazard, not just a nuisance.
How do I know if I need a noise survey?
If employees regularly have to raise their voice to be heard at arm's length, or if you operate equipment known for high noise output, a survey is worth doing. Only a measurement can confirm whether exposures are below the action level, between the action level and PEL, or above the PEL — each triggers different obligations.
What does a professional noise survey actually involve?
Representative sampling using calibrated dosimeters and sound level meters across job tasks and work areas, calculation of 8-hour time-weighted averages, identification of which employees are exposed at or above the action level, and a written report identifying specific noise sources and recommended controls.
Does hearing protection alone satisfy the requirement?
No. Once exposure reaches the action level, a full hearing conservation program is required, including monitoring, audiometric testing, training, and recordkeeping. Once exposure reaches the PEL, a documented evaluation of feasible engineering and administrative controls is also required — hearing protection is one component, not a standalone solution.
How often does monitoring need to be repeated?
Whenever a change in production, process, equipment, or controls could reasonably increase noise exposure, or introduce new employees to a noise-hazardous area. There is no fixed calendar interval — it is tied to whether conditions have changed.
What is a Standard Threshold Shift, and why does it matter?
A Standard Threshold Shift (STS) is an average hearing loss of 10 dB or more at 2000, 3000, and 4000 Hz in either ear compared to an employee's baseline audiogram. Detecting an STS early through annual testing is what allows a program to intervene before hearing loss becomes severe or permanent.
Is hearing protection selection the same as a PPE hazard assessment?
No. Selecting hearing protectors is one output of a hazard assessment, not the assessment itself. A compliant PPE hazard assessment under 8 CCR §3380 is a written, task-by-task determination covering every applicable hazard category — noise, eye, hand, respiratory, and others — with documentation showing why each PPE selection was made, including whether the NRR on your hearing protectors is adequate for measured exposure levels.
Is NIOSH the same as OSHA, and do I have to follow their standard?
No. NIOSH is a research agency and does not enforce compliance or issue citations; Cal/OSHA and federal OSHA do. NIOSH's Recommended Exposure Limit uses a 3 dB exchange rate rather than OSHA's 5 dB rate, which makes it more protective at the same headline noise level. Following NIOSH's recommendation is not legally required, but it is a useful benchmark for facilities that want to reduce hearing loss risk beyond the legal minimum.
Request a Noise Survey and Compliance Review
Plaid Safety conducts noise surveys, builds Cal/OSHA-compliant Hearing Conservation Programs, identifies feasible source controls, and can fold hearing protection into a full written PPE hazard assessment for industrial and manufacturing facilities across LA, Orange, San Diego, and Riverside Counties — as a standalone project or as part of our monthly Compliance-as-a-Service plans.
Industrial Noise Survey & Assessment for Southern California Facilities
If your floor is loud enough that employees raise their voice to be heard, noise exposure is a regulated hazard, not just a nuisance — governed at both the state and federal level. Plaid Safety conducts on-site noise surveys and dosimetry for manufacturing, metal fabrication, machine shops, plating and finishing operations, and other high-noise industrial facilities, calculates 8-hour time-weighted averages, and builds the hearing conservation program and source control plan your facility actually needs.
Schedule a Noise Surveythe action level (8-hour TWA) that triggers a mandatory Hearing Conservation Program under Cal/OSHA and federal OSHA.
the Permissible Exposure Limit (PEL) that requires a documented evaluation of engineering and administrative controls.
the peak sound pressure ceiling for impulsive or impact noise — a single gunshot-like event can exceed it instantly.
Facilities That Typically Need a Noise Survey
Noise exposure risk isn't evenly distributed. It concentrates in specific processes and equipment types — if any of these describe your operation, a survey is worth doing before an inspection or a hearing complaint forces the question.
Common High-Noise Operations
- Metal fabrication, stamping, and sheet metal work
- Machine shops and CNC operations
- Plating, finishing, and surface treatment lines
- Plastics and injection molding
- Packaging and print production floors
- Warehousing and distribution with heavy material-handling equipment
- Any facility running compressors, generators, or pneumatic tools continuously
Signs Your Facility May Already Be Non-Compliant
- Employees have to raise their voice to be heard at arm's length
- Workers report ringing in their ears at the end of a shift
- You've never measured noise levels, only relied on equipment spec sheets
- You run 10- or 12-hour shifts and assumed 85 dBA compliance is automatically sufficient
- New equipment or a process change has been added since your last (or only) assessment
Why a Manufacturer's Spec Sheet Isn't Enough
Equipment noise ratings describe a machine in isolation. Your workplace is not a lab.
Real conditions differ from the spec sheet
Installation, maintenance condition, surrounding equipment, and room acoustics all change actual noise levels. A professional survey measures what's really happening on your floor, not what a catalog says a machine should produce.
Exposure is cumulative, not just peak volume
Compliance is based on an 8-hour time-weighted average, not a single loud moment. An employee moving between a quiet task and a loud one all shift can still exceed the action level even if no single reading feels extreme.
Extended shifts change the math
Facilities running 10- or 12-hour shifts often assume 85 dBA compliance is sufficient without adjusting for shift length. Longer shifts lower the exposure level at which the same cumulative dose is reached.
Hearing protection alone isn't a program
Handing out earplugs without monitoring, audiometric testing, training, and a documented evaluation of feasible controls does not satisfy the standard. A compliant program has several required components working together.
Your Noise Survey Feeds a Larger Requirement: the PPE Hazard Assessment
Handing out earplugs isn't the same as documenting that they're the right earplugs. Both Cal/OSHA and federal OSHA require a written PPE hazard assessment, and noise is one hazard it has to address.
Under 8 CCR §3380 (and the federal equivalent, 29 CFR §1910.132), employers must conduct and document a workplace hazard assessment to determine what PPE is actually required for each job task — noise is one category alongside eye, hand, respiratory, and fall protection. For hearing protection specifically, that means the Noise Reduction Rating (NRR) on the devices you provide has to be matched against your measured exposure levels, not selected off a shelf. Overprotecting isolates employees from warning signals and coworker communication; underprotecting leaves the exposure unmanaged. A noise survey gives you the actual numbers the hazard assessment is supposed to be based on — without it, the PPE selection is a guess, not a documented determination.
Plaid Safety can fold your hearing protection determination into a broader PPE hazard assessment covering every task and hazard category at your facility, not noise alone — so one site visit satisfies more than one regulatory requirement.
Source Control: The Preferred First Response
Once exposure reaches the 90 dBA PEL, Cal/OSHA and federal OSHA both require a documented evaluation of engineering and administrative controls before hearing protection is treated as the primary solution. Source control comes first for a reason: it reduces exposure for everyone in the space, not just the one person wearing protection correctly.
Engineering controls at the source
Equipment substitution, isolation, vibration damping, mufflers, enclosures, and routine maintenance that keeps machinery from generating excess noise in the first place. This is where a survey earns its value — identifying which specific source is driving the exposure.
Controlling how noise travels
Acoustic barriers, sound-absorbing materials, distance, and facility layout changes that reduce how much noise reaches an employee's work area, even when the source itself can't be fully quieted.
Limiting exposure time
Job rotation, scheduling, and work practice changes that reduce how long any individual employee spends in a high-noise area during a shift.
Hearing protection devices
Required whenever exposure remains at or above the action level after feasible controls are applied — but PPE depends on correct fit, consistent use, and proper attenuation, and protects only the individual wearing it.
Cal/OSHA and Federal OSHA: Related, Not Identical
California employers are governed by Cal/OSHA's noise standard, not the federal one — and the two aren't interchangeable.
Cal/OSHA
8 CCR §§5095–5100- Action level: 85 dBA, 8-hour TWA
- PEL: 90 dBA, 8-hour TWA
- Impulsive/impact noise ceiling: 140 dB peak
- Requires posting a copy of the noise regulation in the workplace — a requirement with no federal equivalent
- Baseline audiogram within 6 months of first exposure (12 months if mobile testing is used, with hearing protection provided in the interim)
Federal OSHA
29 CFR §1910.95- Action level: 85 dBA, 8-hour TWA
- PEL: 90 dBA, 8-hour TWA
- Similar hearing conservation program structure
- No standalone workplace posting requirement for the noise regulation itself
- Applies outside California and to certain federally regulated operations
NIOSH Sets a Stricter Bar Than the Legal Minimum
Compliance and genuine hearing protection aren't always the same number. NIOSH is worth understanding even though it doesn't issue citations.
The National Institute for Occupational Safety and Health (NIOSH) is a federal research agency, not an enforcement agency — it doesn't inspect facilities or issue citations the way Cal/OSHA and federal OSHA do. But NIOSH sets its own Recommended Exposure Limit (REL) for noise at 85 dBA as an 8-hour TWA, using a 3 dB exchange rate rather than OSHA's 5 dB exchange rate. That difference sounds small and isn't: under NIOSH's 3 dB rate, every 3 dB increase in noise level cuts the "safe" exposure time in half, versus every 5 dB under OSHA's rate. In practice, that makes NIOSH's standard meaningfully more protective at higher noise levels, even though the headline number — 85 dBA — matches Cal/OSHA and federal OSHA's action level.
For employers, this means a facility can be fully compliant with the legal standard and still be operating above what NIOSH considers genuinely protective of hearing over a career. Plaid Safety reports both figures where relevant, so you can see the difference between "compliant" and "how NIOSH would evaluate the same data" — and decide whether closing that gap with additional source control is worth it for your workforce, not just your inspection risk.
Noise Surveys and Hearing Conservation: Common Questions
What employers most often ask once they realize noise exposure is a regulated hazard, not just a nuisance.
How do I know if I need a noise survey?
If employees regularly have to raise their voice to be heard at arm's length, or if you operate equipment known for high noise output, a survey is worth doing. Only a measurement can confirm whether exposures are below the action level, between the action level and PEL, or above the PEL — each triggers different obligations.
What does a professional noise survey actually involve?
Representative sampling using calibrated dosimeters and sound level meters across job tasks and work areas, calculation of 8-hour time-weighted averages, identification of which employees are exposed at or above the action level, and a written report identifying specific noise sources and recommended controls.
Does hearing protection alone satisfy the requirement?
No. Once exposure reaches the action level, a full hearing conservation program is required, including monitoring, audiometric testing, training, and recordkeeping. Once exposure reaches the PEL, a documented evaluation of feasible engineering and administrative controls is also required — hearing protection is one component, not a standalone solution.
How often does monitoring need to be repeated?
Whenever a change in production, process, equipment, or controls could reasonably increase noise exposure, or introduce new employees to a noise-hazardous area. There is no fixed calendar interval — it is tied to whether conditions have changed.
What is a Standard Threshold Shift, and why does it matter?
A Standard Threshold Shift (STS) is an average hearing loss of 10 dB or more at 2000, 3000, and 4000 Hz in either ear compared to an employee's baseline audiogram. Detecting an STS early through annual testing is what allows a program to intervene before hearing loss becomes severe or permanent.
Is hearing protection selection the same as a PPE hazard assessment?
No. Selecting hearing protectors is one output of a hazard assessment, not the assessment itself. A compliant PPE hazard assessment under 8 CCR §3380 is a written, task-by-task determination covering every applicable hazard category — noise, eye, hand, respiratory, and others — with documentation showing why each PPE selection was made, including whether the NRR on your hearing protectors is adequate for measured exposure levels.
Is NIOSH the same as OSHA, and do I have to follow their standard?
No. NIOSH is a research agency and does not enforce compliance or issue citations; Cal/OSHA and federal OSHA do. NIOSH's Recommended Exposure Limit uses a 3 dB exchange rate rather than OSHA's 5 dB rate, which makes it more protective at the same headline noise level. Following NIOSH's recommendation is not legally required, but it is a useful benchmark for facilities that want to reduce hearing loss risk beyond the legal minimum.
Request a Noise Survey and Compliance Review
Plaid Safety conducts noise surveys, builds Cal/OSHA-compliant Hearing Conservation Programs, identifies feasible source controls, and can fold hearing protection into a full written PPE hazard assessment for industrial and manufacturing facilities across LA, Orange, San Diego, and Riverside Counties — as a standalone project or as part of our monthly Compliance-as-a-Service plans.