14,730 occupational hearing loss cases. 1,004 companies. An average of 14.7 cases per company — the second-highest concentration of any U.S. manufacturing sector. Transportation Equipment Manufacturing, NAICS 336, produces vehicles, aircraft, ships, and related equipment under some of the highest-noise production conditions in American industry. OSHA 1910.95 applies wherever workers are exposed at or above the 85 dBA action level, and stamping, welding, grinding, and machining operations in this sector routinely exceed that threshold. According to the CDC, approximately 22 million U.S. workers are exposed to hazardous occupational noise annually. This guide examines the sector’s hearing loss data, identifies the subsectors driving the highest case volume, and frames the compliance and WC exposure profile for employers in this industry.
A Tier 2 automotive stamping supplier with 180 production workers had operated under the assumption that their OEM customer’s annual safety audit covered hearing conservation compliance. When an OSHA inspector visited following a separate safety incident, he identified three 1910.95 deficiencies: outdated noise monitoring (last survey was 11 years prior after significant equipment additions), a professional supervisor whose credentials had lapsed, and STS records showing notifications had never been sent to affected workers. The OEM’s audit had checked the box; OSHA checked the program.
Transportation equipment manufacturing hearing loss data is heavily concentrated in the automotive supply chain — but that concentration means many individual facilities have exposure profiles that are better or worse than the sector average. Knowing where your facility sits is the starting point for calibrating your program response.
Sector Profile and Case Data
Transportation equipment manufacturing is defined by three operational characteristics that drive its elevated hearing loss case concentration: continuous high-noise production processes, large workforce size at individual facilities, and a multi-tier supply chain structure where Tier 2 and Tier 3 suppliers often have significantly weaker HCP infrastructure than their OEM customers.
The sector’s 14.7 average cases per company significantly exceeds most manufacturing sectors, reflecting both the intensity of noise exposure in vehicle manufacturing operations and the scale of workforce at individual plants.
Subsector Breakdown
Within NAICS 336, hearing loss case volume and noise intensity vary substantially by subsector:
| Subsector | 9-Year Cases | Typical TWA | Primary Operations |
|---|---|---|---|
| Motor vehicle body & trailer (3362/3369) | 4,821 | 90–105 dBA | Stamping, welding, painting |
| Motor vehicle parts (3363–3365) | 4,210 | 85–100 dBA | Machining, casting, assembly |
| Aerospace products (3364) | 2,768 | 85–95 dBA | Riveting, engine test, grinding |
| Ship & boat building (3366) | 1,921 | 90–105 dBA | Grinding, blasting, welding |
| Other transportation equipment (3369) | 1,010 | 80–95 dBA | Varies |
Primary Noise Sources
Transportation equipment manufacturing’s most noise-intensive operations:
- Stamping and press operations: Metal stamping for body panels, frames, and structural components produces impact noise peaks that are among the highest in manufacturing (90–110 dBA peak; 90–105 dBA TWA for press operators)
- MIG/TIG/spot welding: Welding operations produce sustained noise from equipment operation and metal interaction (85–95 dBA)
- CNC machining and grinding: Precision machining of drivetrain components (85–100 dBA depending on material and speed)
- Abrasive blasting: Surface preparation in ship and boat building and aerospace operations (90–110 dBA)
- Engine and component testing: Acoustic test cells and dynamometer testing for finished components (90–115 dBA)
Common HCP Compliance Gaps
- OEM audit as OSHA proxy: Tier 2 and Tier 3 suppliers frequently treat OEM customer safety audits as OSHA compliance validation. OEM audits check for program existence; OSHA inspections check program substance. The gap is significant.
- Equipment additions without re-monitoring: Continuous capital investment in stamping and machining equipment invalidates prior noise surveys. Many facilities have added capacity without triggering re-monitoring.
- Contract and temporary workforce enrollment gaps: Automotive manufacturing uses contract and temporary workers extensively. These workers frequently work in noise-exposed roles but fall outside HCP enrollment because they are not direct employees.
- PS credential maintenance at multi-site programs: Large automotive suppliers with 10–30 facilities often rely on a single named PS. When that PS retires or changes roles, facilities continue operating without a valid licensed PS, invalidating all STS determinations made during the lapse.
WC Claim Exposure Profile
- Claims concentrate in motor vehicle body and parts operations where TWA exposures are highest and workforce tenure is longest
- Bilateral high-frequency hearing loss with 4 kHz notch pattern is the dominant audiometric profile in WC claims from this sector
- Multi-employer prior noise histories are common — production workers frequently transition between Tier suppliers over careers of 20+ years
- Last-injurious-exposure claims are a significant risk for employers that hire workers from other automotive manufacturers
Frequently Asked Questions
The sector’s 14.7 average cases per company is the second-highest concentration in U.S. manufacturing, driven by high-noise stamping, welding, and grinding operations, long-tenured skilled workforces with high cumulative noise dose, and weaker HCP infrastructure at Tier 2/3 suppliers.
Stamping and press operations (90–105 dBA), MIG/TIG welding (85–95 dBA), CNC machining of drivetrain components (85–100 dBA), abrasive blasting (90–110 dBA), and engine/component testing in acoustic test cells (90–115 dBA).
OEM audit pass-throughs that don’t reflect actual OSHA compliance, outdated noise monitoring after equipment additions, contract/temporary workforce enrollment gaps, and PS credential lapses at multi-facility programs.
HCP programs built for high-volume automotive and transportation manufacturing
Soundtrace’s platform handles multi-facility audiometric programs, automated STS detection, cloud record retention, and licensed PS review for transportation equipment manufacturers at every tier of the supply chain.
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