Which statement about hearing loss is true?

• A. Hearing loss is caused only by aging
• B. Hearing loss is caused by noise alone
• C. Hearing loss cannot be caused by noise
• D. Noise-induced hearing loss and presbycusis are synergistic

Answer: (D)

Two processes—noise-induced damage and aging—can interact in a way that the combined hearing loss is greater than the sum of each part. Noise exposure damages cochlear hair cells and other structures, causing permanent sensorineural loss. Presbycusis is the gradual, age-related decline in hearing. When both are present, their effects add up in a synergistic way, meaning the overall loss can be amplified beyond simple addition. This is why an older worker with a history of noisy exposure may experience more hearing loss than would be predicted by age or noise exposure alone.

The other ideas aren’t accurate because aging can contribute to hearing loss but isn’t the sole cause, and noise exposure can cause hearing loss on its own. Saying noise causes hearing loss “alone” ignores other factors, and claiming noise couldn’t cause hearing loss contradicts well-established evidence.