If you’ve ever left a concert or a shooting range and noticed that everything sounds a little bit quieter, you’re experiencing what’s known as a threshold shift. Threshold shifts are typically temporary and mild, occurring after exposure to loud noise.
What Does a Threshold Shift Feel Like?
Threshold shifts are so named because the “threshold” of sound that you’re able to hear changes. Under normal circumstances, your auditory threshold can detect quiet sounds, such as footsteps and whispered conversations, as well as high-pitched sounds, like the microwave beeping or birds singing. If that auditory threshold changes, then the quietest level of sound you’re able to pick up rises slightly.
You will notice difficulty hearing sounds you’re generally able to hear, a muffled feeling inside the ear, or even tinnitus.
Why Does Loud Noise Cause a Threshold Shift?
Inside the inner ear, there are tiny, hair-like sensory cells that perceive sound waves, translate them to electrical signals and transmit them to the brain. These cells are integral to the hearing process. Loud noises have large, forceful sound waves, and those sound waves can bend or damage the hair cells.
When hair cells are bent or damaged, they are no longer able to transmit sound information to the brain, so you won’t perceive it. The hair cells responsible for picking up high-frequency pitches are usually the first to sustain damage, as they are closer to the entrance of the ear. Therefore, in the event of damage, you will either not hear high-pitched sounds at all or your brain will either notice this lack of sound and attempt to fill in the blanks itself, resulting in tinnitus.
Can a Threshold Shift Be Permanent?
Usually, temporary threshold shifts resolve themselves after a few hours or a day, but threshold shifts can be permanent. If hair cells are exposed to loud noises for an extended period, a permanent threshold shift will occur.
You can protect your hearing by wearing ear protection, such as earplugs or earmuffs, and taking breaks from loud noise if you find yourself in a loud environment.
When to Visit an Audiologist
If you’re still experiencing a temporary threshold shift after a few weeks, it’s time to check in with an audiologist. You may have noise-induced hearing loss. If you have symptoms that resemble a threshold shift but haven’t been around loud noise recently, that may also be a good reason to visit an audiologist. Contact Benke Ear Nose & Throat Clinic to schedule an appointment.