A group of researchers from the Center for Audio, Acoustics, and Vibration at the University of Technology Sydney has unveiled a new type of active noise cancellation: it uses a headrest instead of headphones.
Earlier designs have used microphones that are placed in a specific location around the user’s head to pick up sounds. These settings are best suited for low-frequency noise up to 1 kHz. However, there is no passive control for high-frequency noise. And these frequencies also include human speech, the range of which is from 4 to 6 kHz.
The new system, which was developed by a team from Sydney, is designed to work with both high and low frequencies. The researchers used a remote acoustic sensing system based on a laser Doppler vibrometer (LDV) that measures non-contact vibrations over a wide range. They placed a tiny jewelry-sized reflective membrane in the ear of a human model as a sensor for the LDV.
The system suppresses noise from multiple sources at once in the range up to 6 kHz with attenuation from 10 to 20 dB.
The new development can be used, for example, on an airplane. The only limitation is the high cost. Since the system uses LDV.
In the near future, developers will be developing ways to reduce the cost of production.