What can artificially increase hearing thresholds, especially at 500Hz?

Excessive ambient noise is known to artificially increase hearing thresholds, particularly at lower frequencies like 500Hz. When there is a high level of background noise, it can mask the sounds being tested and make the individual's ability to hear them more difficult. This phenomenon is particularly impactful at lower frequencies, as these sounds are more easily masked by surrounding noise.

In hearing assessments, the presence of excessive noise can lead to inaccurate results, as the test subject may not be able to differentiate between the pure tones being played and the competing sounds from the environment. This can falsely indicate that the person has a hearing loss or higher thresholds than they actually do.

While low-frequency ambient noise and low-pitched background sounds might contribute to a similar effect, they do not necessarily reach the threshold of being classified as "excessive," which implies a level strong enough to interfere significantly with hearing tests. High decibel levels from machinery can also have a detrimental effect on hearing but are not specifically tied to artificially increasing thresholds during hearing testing in the same way that excessive ambient noise does.