What is the term for the natural increase in loudness of a tone by bone conduction due to blockage?

The term that refers to the natural increase in loudness of a tone by bone conduction due to blockage is known as the Occlusion Effect. This phenomenon occurs when an individual wears hearing aids or has an ear canal partially blocked, which can lead to an increase in the amplitude of sounds conducted through the bones of the skull. As the ear canal is obstructed, lower frequency sounds become more pronounced, creating a feeling of increased loudness.

In the context of hearing aids, the occlusion effect is particularly important for audiologists and fitters to consider when assessing hearing aid performance and the overall comfort for users. This effect is especially noticeable for individuals with conductive hearing loss where bone conduction becomes a more significant method for sound perception.

Other terms like Shadow Curve and Octave do not pertain specifically to the increase in loudness due to blockage. The Shadow Curve relates to sound propagation and masking effects in audiometry, while an Octave refers to a specific musical interval and does not apply to the context of sound conduction or the occlusion phenomenon. Threshold refers to the lowest level of sound that a person can hear, again unrelated to the mechanics of how bone conduction works in the presence of blockage.