Parametric speaker experiment
The sound radiated by the speaker is transmitted while spreading. The same applies to the radio waves radiated from the antenna. If this spread is small, it will be transmitted strongly only in a specific direction and less likely to be transmitted in other directions. A parametric speaker is a speaker that strongly transmits sound only in a specific direction using ultrasonic waves.
I conducted an experiment on a parametric loudspeaker with the aim of making it possible to understand what is directivity and what is wave propagation. Here, we used the parametric speaker which is already on market. This parametric speaker consists of 100 ultrasonic transducers, and the low frequencies modulated by these ultrasonic waves can be heard.
I set up the instrument and emitted a sound wave. On the other hand, while moving to the end of the corridor, he confirmed how far this sound reached.
I was able to clearly hear the sound coming from this parametric speaker even when I was far from the end of the corridor. When it came off a little from the front of the speaker, the sound coming from it became difficult to hear.
Next, with the front of the speaker facing the other side of the passage, we confirmed how far the sound waves reflected by the glass could reach.
The sound reflected from the glass also reached the end of this corridor. On the other hand, on the other side of the glass radiated by the sound waves of the parametric speaker, this sound was quite small.