Headrest Speakers and Noise Cancellation

Sound masking is used in homes, commercial offices, medical facilities, court rooms, and in secure facilities to provide secrecy. With Blue-Tooth rear seat conversation the need for privacy is important especially is driver driven cars or two passengers in rear seat wanting privacy when talking on cell phone. Sound masking is by far the least expensive tool for providing privacy.

Cambridge Sound Management is one company that has developed sound masking systems. Qt Quiet Technology sound masking systems provide a discrete background sound, similar to airflow, to reduce distractions, increase speech privacy, and improve productivity. One example is the Qt Patient Privacy System is a cost-effective sound masking solution to protect patient and staff conversations in all types of medical facilities.

Others are Qt® emitters that deliver four uncorrelated audio channels, which provide uniform, unobtrusive sound masking. Designed for plug and play installation and cost effective.

The Austrian engineer Rudolf Stefanich has developed concept device that may be able to cancel the noise passing near you called Sono to attribute its connection to sound.

GM engineers did an experiment in active noise cancellation for other benefits. It relies on two headliner-mounted microphones to detect the hum and a frequency generator emits an antinoise signal through the vehicle ‘s speakers to cancel out the engine ‘s boom – same concept can be used for rear seat privacy conversation.

Speech Privacy Systems is another company specializing in this area. As clarified by them for in car application we are looking for combination of noise cancellation and masking. Sound masking works on the principle that when background noise is added to an environment, speech is less intelligible.  Refer Sound Privacy WEB Page “In technical terms, the “Articulation Index” – a measurement of how intelligible speech is – has been lowered by this change in the signal-to-noise ratio. The “signal” would be, for example, the person speaking, and the “noise” would be the sound masking. A high signal-to-noise ratio means that speech is very intelligible – an amphitheater would have a very high Articulation Index, for example. Based on this principle, scientists and engineers realized that you don’t have to actually stop the sound waves from a speaker’s voice in order to obtain speech privacy, you just have to make the speaker’s words unintelligible”.

LogiSon sound masking technology is another to review. Using small adjustment zones of one to three loudspeakers they are effective at providing masking, while easily blending into the environment.

One example that could be adjusted for rear seat application is their Primary Network Hub PNH-2. The Primary Network Hub features communication technology, Digital Signal Processing (DSP) truly random masking sound generation, a 1/3-octave masking equalizer, a 1/1-octave paging equalizer, an amplifier, independent volume controls for masking and paging, and multiplexed paging selection.

Lencore sound masking is designed to achieve both Speech Privacy and Comfort by introducing a spectrum of noise which gently raises the ambient background sound in order to cover, or mask, speech. Speech Privacy is achieved by raising the noise level to a point that makes conversations unintelligible. Comfort is achieved through the quality and range of the sound produced.

Lencore Spectra® Desktop Sound Masking Unit provides speech privacy in close contact areas. It creates speech privacy by generating a comfortable back ground sound. The Desktop Sound Masking Unit consists of an individual self-contained noise generator, audio amplifier, loud speaker, and power supply unit in a white damped metal enclosure.

MUZO noise cancelling / suppression technology is another to evaluate. They were very successfully funded through Kickstarter – please CLICK to review.

Design HMI LLC is looking to partner with innovator to develop a noise masking device for in car application for privacy between passengers in front and rear seats which having private conversation on the smart phone. Please write to designhmi@gmail.com.

Speakers coupled with noise cancelling is being investigated as MUST HAVE for Autonomous People Movers or even Non-Autonomous vehicles. Concept is to integrate in headrest

One technology solution designed by Rudolph Stefanich, SONO is a noise cancelling device that can be applied to all the windows in your house that allows you to eliminate sounds but also allows you to control each sound individually. You may want to erase the sound of road construction but don’t mind the sound of birds chirping. This device will allow you to custom control the sound in your home. REFER https://www.ippinka.com/blog/sono-peace-quiet-home/ for more information on SONO.

Another is Silentium S-Cube™ (Quiet at the source and QB™) is a Broadband ANC which reduces low-mid frequency noise up to 1.8 KHz. The System Reference sensors feed the noise source to the controller which outputs anti-noise via the loudspeakers. Error microphones provide feedback on the wanted sound signature to refine the effects.

Their Quiet Bubble™ family synthesizes the physical characteristics of the unwanted noise field in a desired zone of quiet. This is achieved by multichannel algorithm that allows controlling the sound field produced by an array of loudspeakers. Refer https://www.silentium.com/technology/quiet-bubble/ 

For this speakers Yamaha TLF speakers emit sound directly from their front surface.  They also transmit sound across long distances with minimal attenuation even at low volumes. Our design proposal was an array of TLF panels hanging from a very thin metal frame. Each panel plays a recording of a synthetic singing voice using Yamaha’s VOCALOID technology, which mix together into a complete choir at a focal point, marked on the floor. Refer http://mapprojectoffice.com/work/yamaha/.

Another technology is piezo actuator used in the new product was born from Kyocera’s proprietary fine ceramic material technology and lamination technology, combined with a special film. Smart Sonic Sound can create the same audio volume as conventional electromagnetic speakers in just a fraction of the width and weight. This allows for the speaker device to be built onto the front face of an end-product with ease ― contributing to flexibility and enhancements in end-product designs.

REFER https://global.kyocera.com/news/2013/0805_ndit.html