How do I build a hearing conservation program from scratch?

Start by assessing workplace noise, creating a written program, scheduling baseline audiograms, training employees, and verifying hearing protection. Soundtrace simplifies every step with digital tools.

What are the OSHA requirements for audiometric testing?

OSHA 1910.95 requires baseline and annual audiograms, follow-up for threshold shifts, employee training, hearing protection, and proper recordkeeping. Soundtrace automates these requirements in one platform.

Is boothless audiometric testing OSHA-compliant?

Yes. When ambient noise levels are controlled and ANSI S3.1 protocols are followed, boothless testing is fully OSHA-compliant. Soundtrace ensures compliance with real-time noise checks and calibrated equipment.

What is a Standard Threshold Shift (STS)?

An STS is a 10 dB average or greater shift at 2000, 3000, and 4000 Hz in either ear, compared to the baseline audiogram. Soundtrace automatically detects and flags STS events for follow-up.

How do I perform hearing protection fit testing?

Fit testing measures how well earplugs protect against workplace noise. Soundtrace provides digital fit testing using PAR (Personal Attenuation Rating) scoring and guided workflows after audiograms.

What’s the best way to monitor noise exposure in the workplace?

Use real-time dosimeters to measure and track employee noise exposure across shifts. Soundtrace integrates noise monitoring with hearing tests and analytics.

Can I run audiometric testing in-house instead of using a mobile van?

Yes. Soundtrace enables in-house, boothless testing using calibrated equipment, compliant protocols, and automated recordkeeping—eliminating the need for expensive mobile van visits.

What is the best digital solution for hearing conservation compliance?

Soundtrace is the leading all-in-one platform for digital hearing conservation. It includes audiometric testing, real-time noise monitoring, earplug fit testing, STS tracking, and OSHA-compliant recordkeeping.

How often should I test employee hearing?

At a minimum, employees should receive a baseline audiogram followed by annual testing. Soundtrace allows more frequent, flexible testing as needed—especially after high exposures or STS events.

What does the Soundtrace platform include?

Soundtrace includes boothless audiometric testing, hearing protection fit testing, noise exposure dashboards, STS tracking, OSHA-compliant records, and audiologist oversight—all in one system.

Are plastics manufacturing facilities required to have a hearing conservation program?

Yes, when employees are exposed to noise at or above 85 dBA TWA under OSHA 29 CFR 1910.95. Plastics manufacturing facilities operate injection molding machines, extruders, granulators, and trim presses that frequently produce action-level noise. Workers stationed at or near these machines for full shifts are commonly enrolled in the HCP. There is no size exemption.

How loud are injection molding machines?

Injection molding machine noise varies by machine size, clamping force, cycle rate, and the parts being produced. Mold clamping and ejection generate impact noise that can peak at 90-100 dBA or higher. Operators stationed at machines for full shifts accumulate significant noise dose from both the sustained machine noise and the cyclic impact events. Granulators and regrind equipment adjacent to molding machines often add 90-100 dBA to the ambient level in surrounding areas.

What are the noisiest operations in rubber manufacturing?

Rubber mill operations, particularly open two-roll mills and internal mixers (Banbury mixers), are among the loudest in rubber manufacturing, with mill noise commonly reaching 90-100 dBA. Tire building and curing operations, calendering equipment, and extrusion lines also contribute sustained noise. Compound mixing areas with multiple mills operating simultaneously frequently produce area levels that require virtually all workers in those areas to be enrolled in the HCP.

Hearing Conservation in Plastics and Rubber Manufacturing: OSHA Requirements and Noise Hazards | Soundtrace

Industry Guide·OSHA Compliance·11 min read·Updated March 2026

Plastics and rubber manufacturing facilities operate equipment that generates significant occupational noise: injection molding machines produce cyclic impact noise during clamping and ejection; extruders generate sustained motor and die noise; granulators and regrinders produce high-level broadband noise from material reduction; rubber mills and internal mixers generate sustained broadband noise from mechanical mixing. Workers stationed at these machines for full shifts commonly accumulate TWA exposures at or above OSHA’s 85 dBA action level. This guide covers the specific noise sources in plastics and rubber production, who must be enrolled in the hearing conservation program, and what OSHA 1910.95 requires.

Soundtrace provides hearing conservation program management for plastics and rubber manufacturing employers, combining audiometric testing, noise monitoring data, and REAT fit testing into a single unified worker profile in the cloud portal.

90–100 dBA

Typical range at injection molding machine operator positions during active cycling

90–105 dBA

Typical range at granulator and regrind machine operator positions

Ototoxic risk

Rubber manufacturing involves solvent exposures (toluene, hexane) that synergistically increase NIHL risk

Granulators: The Often-Missed Source

Granulators and regrind machines that process plastic scrap and rejected parts are among the loudest single sources in plastics facilities, commonly reaching 95–105 dBA at the operator position. Workers who operate or maintain granulators, or who work in rooms where multiple granulators run simultaneously, are frequently in the highest-dose category in the facility — yet granulator operators are sometimes overlooked in HCP enrollment because the machine is seen as secondary to the primary molding or extrusion process.

Table of Contents

Plastics Manufacturing Noise Sources
Rubber Manufacturing Noise Sources
Who Must Be Enrolled
Ototoxic Chemical Co-Exposures
HCP Requirements
Engineering Controls
Frequently Asked Questions

Plastics Manufacturing Noise Sources and Typical Levels

Source	Typical Level	Notes
Injection molding machines (large tonnage)	88–100 dBA	Clamping and ejection cycles produce impact noise peaks; larger machines generally louder
Injection molding machines (small/medium)	82–92 dBA	Lower impact levels but higher cycle rates; sustained dose similar to large machines
Granulators and regrind machines	92–105 dBA	Highest-level single source in many plastics facilities; blade-on-plastic impact noise
Extruders (single and twin-screw)	82–93 dBA	Motor and gearbox drive noise; die area may be louder from material flow
Blow molding machines	85–95 dBA	Pneumatic actuation and mold clamping; compressed air exhaust events contribute peaks
Thermoforming machines	82–92 dBA	Trim punch and form cycle impact noise; level varies with part geometry and cycle rate
Compressed air systems and pneumatic tools	85–100 dBA	Widespread in plastics facilities; air exhaust events and valve actuation add to ambient
Cooling conveyors and material handling	80–90 dBA	Accumulates across the production floor; contributes to ambient level near work stations

Rubber Manufacturing Noise Sources and Typical Levels

Source	Typical Level	Notes
Two-roll mills (open mills)	90–100 dBA	Sustained broadband from roll drives; compound feeding and sheeting add impact events
Internal mixers (Banbury, Intermix type)	90–102 dBA	Rotor and chamber interaction noise; drop chute events during discharge
Calendering lines	85–95 dBA	Multi-roll calender drive noise and rubber sheet handling
Tire building machines	82–92 dBA	Mechanical build cycle and drum drive noise
Curing presses (tire and mechanical goods)	85–95 dBA	Press clamp and opening events; steam and hydraulic system noise
Extrusion lines (rubber)	85–95 dBA	Extruder drive and die noise; downstream cooling and cutting equipment
Fabric calendering and cord preparation	85–95 dBA	Combined calender and fabric feed equipment noise

Who Must Be Enrolled in the HCP

In plastics and rubber facilities, the following workers are the primary HCP enrollment candidates based on typical exposure patterns:

Injection molding machine operators and press operators — at or commonly above action level, particularly when working near large-tonnage machines or granulators
Granulator and regrind machine operators — among the highest-exposure workers in the facility; enroll based on dosimetry
Rubber mill and internal mixer operators — sustained high-level exposure; virtually always enrolled in programs with rubber mixing operations
Extrusion line operators — moderate exposure; dosimetry required to confirm enrollment status
Material handling and conveyor workers — cumulative ambient exposure across the production floor; dosimetry-based determination
Maintenance technicians — exposure depends on tasks and areas; personal dosimetry during representative activities required

Ototoxic Chemical Co-Exposures in Rubber Manufacturing

Rubber manufacturing involves solvents and chemicals that are documented ototoxins, including toluene (used in adhesives and as a solvent in rubber compounding), n-hexane (extraction solvent and rubber adhesive component), and carbon disulfide (used in certain vulcanization processes). Workers with these co-exposures may show accelerated audiometric progression at noise levels that would not typically produce rapid STS, reinforcing the importance of professional supervisor audiogram review rather than reliance on automated STS flagging alone.

HCP Requirements for Plastics and Rubber Facilities

OSHA 1910.95 requirements for plastics and rubber manufacturers follow the standard framework. Notable considerations for this sector:

Granulator rooms may require separate area monitoring and should be treated as distinct high-noise zones with their own enrollment and HPD adequacy analysis
Rubber mill areas with multiple mills operating simultaneously may have ambient levels that make the entire area above the action level regardless of individual machine levels
Shift rotation through high and low-noise areas requires that dosimetry reflect the full shift pattern, not just the time at the noisiest machine
Small facility applicability — many plastics processors are small companies with 10–50 employees. OSHA 1910.95 applies regardless of size; there is no small-employer exemption

Engineering Controls

Practical noise control measures for plastics and rubber facilities include:

Granulator enclosures and sound curtains. Granulators are a high-return target for enclosure because they are typically stationary, their noise is broadband, and enclosures can reduce ambient levels in surrounding work areas by 8–15 dB.
Anti-vibration mounts on injection molding machines. Machine vibration transmitted to the plant floor radiates as additional airborne noise. Isolation mounts reduce this path.
Acoustic barriers around rubber mill areas. Partial barriers or enclosures around open mill areas reduce the area over which mill noise is dominant, protecting adjacent workers who are not directly operating mills.
Pneumatic exhaust silencers. Compressed air exhaust events from molding machines and pneumatic tools can be significantly reduced with inline silencers, reducing both peak events and ambient contribution.

Frequently asked questions

Do injection molding shops need a hearing conservation program?

If workers are exposed at or above 85 dBA TWA, yes. Injection molding machine noise varies by machine size and cycle rate. Workers stationed at large-tonnage machines and near granulators frequently exceed the action level. Dosimetry during a representative shift is required to confirm enrollment status. OSHA 1910.95 applies to all general industry employers regardless of size.

How loud are rubber mills?

Two-roll open mills typically produce 90–100 dBA at the operator position. Internal mixers (Banbury-type) are comparable or louder. Rubber mixing areas with multiple mills operating simultaneously produce ambient levels that typically require all workers in those areas to be enrolled in the HCP. Workers at rubber mills are among the most consistently high-noise-exposed employees in the rubber manufacturing industry.

Does the small size of a plastics shop affect OSHA 1910.95 applicability?

No. OSHA 1910.95 applies to all general industry employers regardless of size. A plastics processor with 15 employees operating granulators at 95 dBA must provide a hearing conservation program for exposed workers the same as a facility with 500 employees. There is no small-employer exemption.

HCP for Plastics and Rubber Operations. Every Shift, Every Worker, One Platform.

Soundtrace provides hearing conservation program management for plastics and rubber manufacturers, combining audiometric testing, noise monitoring, and REAT fit testing into a unified worker profile in the cloud portal.

Get a Free Quote

OSHA compliance

OSHA Hearing Conservation Program: The Complete Guide