Validation of Acoustical Performance Testing

USG Corporation, an industry-leading manufacturer of building products and innovative solutions, engaged an acoustic testing facility for testing of its gypsum products in a variety of construction systems. Manufacturers of construction and building materials regularly test their products for acoustical performance in walls, floor-ceiling assemblies, roof systems, etc. Building codes and design standards specify minimum acoustical requirements for these construction systems and assemblies, so accurate testing is vital.

Challenge

USG conducted airborne sound transmission loss testing of partition systems containing its gypsum products.  Testing was conducted in an accredited acoustical laboratory per the ASTM E90 Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements.  Sound was generated on one side of the test partition and sound levels were measured on both sides of the partition to determine how much noise was blocked by the specimen.  However, the measured performance was lower than anticipated and anomalies in the resulting data indicated potential issues with the installation of the specimen.  Visual inspection of the test partition did not immediately identify any issues or sound flanking paths.

Solution

VisiSonics 5/64 Audio Visual Camera allows for acoustic visualization, making detecting the source of sound and leaks much easier. Like a heatmap, the Audio Visual Camera provides “hot spots” on a visual panorama to highlight the location and pressure level of sounds. Using both video cameras and microphones along with software, the VisiSonics solution simultaneously generates a synchronized and co-registered audio and video view of the captured environment.  The camera output allowed USG engineers and the testing facility team to isolate where sounds were coming from and determine that airborne sound was leaking around the test partition.

“The VisiSonics Audio Visual camera allowed us to find airborne sound leaks around the test partition that were not apparent during visual inspection. After sealing these sound flanking paths, we achieved a more accurate measure of the test partition with higher STC results. The VisiSonics technology let us visualize sound in a way we couldn’t otherwise.”

Andrew Schmidt, Senior Researcher, Acoustics – USG

Result

VisiSonics camera and accompanying software allowed the USG engineers to see airborne sound leaks around the test partition, which helped to explain the unexpected results during initial testing. In this way, the flanking paths and leaking noise were mitigated prior to the final validation testing.  This resulted in a more accurate measure of the sound passing through the test partition and a more accurate and improved STC rating for the USG assembly.

Sound flanking identified: Air leak through perimeter

+3 STC in measurement after flanking path was mitigated

 

 

 

 

 

 

 

Contact VisiSonics for this and other applications where accurate acoustic measurements are necessary for noise mitigation.

VisiSonics RealSpace 3D Spatial Audio Expands its DSP-based Headphone Technology to include TWS

With the headphone market continuing to grow due to expanding applications in the gaming, music, virtual meeting and other spaces, VisiSonics has been working with industry leaders (including OEMs, ODMs, chipset manufacturers, and design houses) to make it easy and seamless for headphone manufacturers to incorporate our spatial audio with head tracking into their products.

VisiSonics has recently completed its work porting its RealSpace 3D spatial audio to the major DSP chip systems including

TWS (True Wireless Stereo) headphones are quickly  becoming a  preferred form factor for wireless headphones. However, most of the leading TWS headphones have been optimized for voice and  music applications.  This tiny form factor currently contains Bluetooth, microphones, and onboard processing via DSP chips.  With the greater functionality requirements of applications beyond music, the form factor will need to incorporate noise cancellation, headtracking and spatial audio, all of which create power and resource constraints within the headset and the need for more and more powerful chip systems.

Contact us to learn more about RealSpace 3D spatial audio and how our engineering team can help you launch your next headphone, including in the TWS form factor.  We also offer additional capabilities on these devices, including headphone personalization and audiogram measurement via customized apps that can deliver the full experience to your customers.

What are HRTFs and how is VisiSonics Revolutionizing Them?

Our ears are unique to us. Yes they help us hear, but they also play a significant role in how we perceive sound. The shape of the outer ear, or pinna, as well as the shape of our heads and torsos – parameters that are unique to each and every one of us – all play a part in coloring the sound that our ears receive. Accordingly, our hearing systems and individual listening experiences become finely tuned to our specific anatomy.

Small differences in the measurements or relationships associated with one’s physiology can have a dramatic effect on sound accuracy and realism.

A Head Related Transfer Function (HRTF) characterizes how an ear receives a sound from a point in space. It is an equation that defines the way sound scatters off a person’s head, shoulders and ears, and ultimately enters the ear canals. Together with room modeling, it is one of the defining elements in an effective virtual spatial audio environment.

The ability to experience spatial audio content through headphones requires a process known as binaural rendering. This allows stereo headphones to create the perception of space and dimensionality through the two stereo channels. Most engines rendering binaural audio rely on a single default HRTF that represents average physical characteristics. It can be considered an HRTF captured from the average human ear. This model, however, does not factor physical differences that can vary person to person, such as the aforementioned parameters: the shape and dimensions of one’s head, ears, or shoulders. Even minor physical differences between one’s anatomy and the default HRTF can result in a very compromised spatial audio listening experience.

The ability to capture a personalized HRTF specific to one’s ears is fundamental to the process of creating a customized spatial audio experience, optimized to that given person’s hearing and sound perception systems.

Incorporating individualized HRTFs into a high fidelity sound engine can significantly improve the perceived quality and realism of binaurally rendered spatial audio. Accordingly, a way to capture personalized HRTF is clearly not only important, but highly desirable.

Traditional methods of measuring individual HRTFs tend to be cumbersome, expensive, and require physical access to the subject. These methods aren’t practical for most, due to the considerable amount of equipment and know-how required to obtain the data. To address these issues, VisiSonics developed a method to extract HRTFs from easy-to-obtain visual information, aided by machine learning and our proprietary database of traditionally acquired HRTFs.

With VisiSonics technology, it is possible to generate an accurate HRTF from individual pictures of the left and right ears, easily taken from a smartphone.

We use a combination of anthropometric feature matching and low frequency “head-and-torso” (HAT) models to create a personalized HRTF. Given a subject’s ear photos and head measurements, the model is used to extract photo landmarks, which are then used to find the closest ear matches from our extensive HRTF database. As a subject’s left and right ears may differ considerably, we process the left and right ears individually. We do not assign significance to whether any given ear is a left or right ear. By doing so, we can match a right ear to a left one, or vice versa, in order to find the best match.

A personalized HRTF is then generated from the matched ears, which is then further tuned to adjust the HRTF to better fit the aforementioned head measurements. In addition, VisiSonics takes personalization to the next level with audiogram technology that enables customization based upon individual listening capabilities.

VisiSonics personalizes sound with our unique, customized HRTF modeling and audiogram measurements.

At VisiSonics, we combine our spatial audio rendering engine and personalization technology to create a fully optimized sound, customized to each individual’s ears. Thus, a few small steps using a smartphone are all it takes to enjoy immersive, custom tailored spatial audio experiences.

We currently make HRTFs available to integrate with all our RealSpace 3D Spatial Audio applications. This includes our embedded DSP solutions, software solutions and our plugins for gaming developers using Wwise, Unity and Unreal.

Contact us today to discuss how you can integrate RealSpace into your next product.