Toolbox Talk – Temporary vs Permanent Threshold Shift

It explains the early warning signs of hearing damage — and highlights that Temporary Threshold Shift (TTS) is reversible but becomes Permanent (PTS) with repeated exposure. This makes it a great educational tool to encourage early action before permanent damage sets in.

What is a Threshold Shift?

It’s when your hearing temporarily or permanently becomes less sensitive after exposure to loud noise.

Temporary Threshold Shift (TTS):

• Happens after short exposure to loud sounds (e.g., machinery, concerts).
• Hearing feels “muffled” or there’s ringing (tinnitus).
• It goes away after a few hours or days.
• But repeated TTS episodes mean you’re on the road to permanent damage.

Permanent Threshold Shift (PTS):

• Caused by prolonged or repeated exposure, or sudden blasts (e.g., explosion).
• It’s irreversible — hair cells in the ear are damaged or destroyed.
• Leads to Noise-Induced Hearing Loss (NIHL).

Warning Signs to Watch For:

• Ringing or buzzing in the ears after a shift.
• Struggling to hear conversations in noisy areas.
• Needing to turn up the volume more often.

What You Can Do:

• Wear your hearing protection properly — every time.
• Get your hearing tested annually.
• Don’t ignore ringing — it’s your ear’s check engine light.
• Rotate jobs if noise is constant or ask for quieter tools if possible.

Download the full Toolbox Talk document on Temporary vs Permanent Threshold Shift below:

Download