The linear horn, also known as the straight-sided horn, is a cone-shaped shell with no curvature, it is the oldest and simplest design. The pressure change through the horn is linear as a sound wave moves through it, so there is no distortion of the sound. The gradual change in the cross-sectional area of the horn decreases distortion and provides a good phase response due to compressed air in the throat. Devices intended to reproduce human voices, such as the megaphone, are usually conical because the shape reduces the production of harmonics and presents the most accurate reproduction of the original sound. (33)
Exponential Horn:
The exponential horn has a specific acoustic loading property that allows the speaker driver to remain evenly balanced in output level over its frequency range. (34) Exponential horns are defined as horns for which the axial length is exponentially related to the area of the horn. …show more content…
Shape selection: In the first step we chose the available Pinard Horn as an acoustic amplifier to attach it to the microphone, however, soon after we chose to print a linear horn and test its acoustic performances comparing to the last one in order to suit the microphone with the selected shape.
Good results were shown during the tests established on an adult heart: There are no big differences between the available Pinard horn and the printed horn. The linear horn has the least signal distortion, and the best phase response because of its gradually changing cross-sectional area. However, the other ones produces more distortions because of their significant curvatures.
Furthermore, another solution that was established in order to reduce the ambient noises was to equip the opening of the horn with a skinny diaphragm.
The printed horn