Low-loss ultrasound transmission through glass assisted by resonance.

We have investigated transmission of ultrasound signals from a speaker in air through a 400 µm thick borosilicate glass plate, similar to those found in consumer electronics products such as mobile phones and tablets. In order to enhance transmission, we took advantage of resonances in the glass plate and a cavity, which is placed between the glass and the microphone. The results show that it is possible to achieve transmission of a signal with bandwidth of approximately 5 kHz with less than -10 dB attenuation, and only -2 dB attenuation at the resonance peak frequency.