Normal Hearing Range for Work

A great question arose during the job analysis section of our 2-day pre-conference workshop on Cutting Edge MSD Prevention Strategies, at ASSP 2025 in Orlando last month. One of the course participants asked:

“When doing a job analysis, how do we quantify the hearing requirements necessary for work?”

Why Hearing Requirements Are Important to Job Analysts

At ErgoScience, we primarily evaluate the physical demands of work (lift, carry, push, pull, squat, reach, etc.) and the worker's correlating physical abilities. We are not typically involved with evaluating the job's hearing requirements or measuring the worker’s hearing abilities.

However, as job analysts, we must be knowledgeable about hearing requirements for work if this topic arises regarding job accommodation, hiring job applicants, or making return-to-work decisions. The answer to this question also provides information that could be included in a job analysis report if the employer wishes to be specific regarding the hearing requirement for their jobs.

Hearing normal speech is important to most jobs that involve communication, which is the majority of jobs. Hearing could be particularly important in work environments where hearing alarms can mean life or death.

On some job analysis forms, the job analyst is asked to determine if hearing is within speech range and/or if hearing within all ranges is required for the job. Two corollary questions arise:

• What is considered adequate hearing in all ranges?
• What is considered adequate hearing within speech range?

Answering these questions is one of the few times in job demands analysis where we must rely on normative data.

Adequate Hearing for Speech

The ability to hear is measured in decibels (dB HL). Adequate hearing for speech is defined as the quietest sounds a person can hear across a range of frequencies that are important for understanding speech. The ability to hear is tested within 250 Hz to 8000 Hz, which covers most speech sounds. If someone has thresholds of 0–20 dB HL at all tested frequencies, they are considered to have normal hearing. They should be able to:

• Detect soft speech
• Hear conversations in quiet environments
• Pick up most environmental sounds

Adequate Hearing for Alarms

Another issue related to safety and hearing at work is the ability to hear an alarm in an industrial environment. To hear an alarm in an industrial environment, a person must have hearing sensitive enough to detect sounds significantly louder than normal conversation. Industrial alarms are designed to cut through high ambient noise levels (often 85–100 dBA or more).

The typical Industrial Alarm has:

• A volume of 85–120 dB(A), depending on the environment
• A frequency range of 500 Hz to 3000 Hz (where human hearing is most sensitive)

The duration can be continuous or pulsed to attract attention, including tonal, broadband noise, or voice alarms.

If someone has a hearing loss greater than 40 dB HL at key frequencies, they may not reliably detect alarms over industrial noise without amplification or accommodation.

The chart below indicates the thresholds for normal hearing

Example:

Let’s say the ambient noise in a plant is 90 dBA, and the alarm is set at 105 dBA:

• The alarm is 15 dB above ambient (good audibility margin).
• But if the worker has a 50 dB HL threshold at 1000 Hz, they may not detect it well unless it’s even louder or supported with visual/vibratory cues.

Workplace Accommodation Options for Significant Hearing Loss

Despite the importance of adequate hearing for work, some settings lend themselves to accommodation. Table 1 below indicates the various categories of accommodations, how they work, and the best use cases for each.

Table 1.

In Summary:

To hear normal speech, a worker must have hearing within the thresholds of 0–20 dB HL at all tested frequencies. To hear alarms safely in industrial environments, a worker’s hearing thresholds should ideally be:

• ≤ 25 dB HL at 500–3000 Hz
• ≤ 40 dB HL at a minimum to detect loud alarms (with some struggle in background noise)

Accommodations available for workers with hearing loss include modified PPE, procedural changes, environmental modifications, visual and tactile cues, and communication aids. Selection depends on the use case for which they are intended. Workers with greater hearing loss may need visual alarms, vibrating alerts, or amplification devices.