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):

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

Permanent Threshold Shift (PTS):

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

Warning Signs to Watch For:

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

What You Can Do:

1. Wear your hearing protection properly — every time.
2. Get your hearing tested annually.
3. Don’t ignore ringing — it’s your ear’s check engine light.
4. 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:

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