What is the effect of narrowing the end of a horn in acoustics?

Narrowing the end of a horn in acoustics primarily enhances the horn's ability to project sound by altering how the sound waves are distributed. Specifically, when the end of a horn is narrowed, it tends to create a higher impedance at that opening, which can lead to a reduction in the production and transmission of high-frequency sounds. This occurs because higher frequencies, which have shorter wavelengths, are more sensitive to changes in the geometry of the propagation medium. The narrowing acts like a filter, leading to a dampening effect on these shorter wavelengths, making it more difficult for them to escape from the horn.

In contrast, lower frequencies, which have longer wavelengths, are less affected by such geometric changes. Therefore, the narrowing does not have a significant negative impact on lower frequencies; in fact, it could allow them to project more effectively due to increased efficiency in certain designs. Overall, the key effect of narrowing the end of a horn in acoustics is the reduction of high frequencies, making it a critical aspect of horn design for specific applications involving sound reproduction or amplification.