“High-Performance Equalizer Proposal for Personalized Listening in Vehicles”
(30 mins)
Jay Chul-Jae Yoo – Radsone Inc.

Inside vehicles is one of the best listening environments. Music streaming apps, YouTube, podcasts from smartphones become major audio sources in cars while HD radio or satellite radio broadcasting are still useful in them. People would like to listen personalized playlists also in vehicles through smartphones connected with by USB or Bluetooth. So, audio sources become more and more personalized but car audio reproduction systems are mostly fixed to pre-tuned settings except their tone controls. Nowadays, many users are familiar to sound effects because they can use and test various effect apps in smartphones. Resultantly, their knowledge of sound was enriched and their own sound preferences become clear. Such users would like to realize personalized listening settings in vehicles too. The most used sound effect shall be an equalizer. Depending on audio sources (e.g. radio, music streaming, USB mp3), music genres, ages, where they are from, the preferred EQ target curves are not same, so the  predetermined tunes by automakers cannot satisfy such diversities. When new potential buyers test-drive, they check also the sound of the car audio systems. If they feel the sound thin or too boosted in their senses, they would not like to buy the cars. Most vehicles only provide tone balance controls, which are the minimal features of EQ. Definitely the tone control is a kind of level that is too insufficient in the age of smartphones. Automakers should consider giving users more control over the sound. In terms of devices, a car has a good system that can provide a high-performance EQ. In the case of smartphones, EQ, which requires processing power, is not provided properly due to limitations in screen size and battery life of them. A recent vehicle audio system has a horizontal screen display of sufficient size and an amplifier with powerful DSPs built-in. It is possible to provide a good enough EQ for consumer control on the display. Various audio sources used in the vehicle are ultimately played back through the vehicle’s amplifier, so applying an EQ to the vehicle’s amplifier enables an integrated control for all sources. In addition, if an EQ is applied at the end of the audio path, the amplifier, it is advantageous in terms of sound quality. Currently, the tone control provided by most vehicles has the advantage of being easy to operate, but the operation range is too limited and the same settings applies to all audio sources. If you increase the bass of the tone control while listening to the radio, you have to adjust it again when listening to speech such as a podcast to enhance the
speech intelligibility. On the other hand, direct controlling various parameters of a Parametric EQ used in pro audio seems too over-spec for the vehicle EQ. In EQ apps provided by smartphones, graphic EQs are mostly used, and users have experience with them.

Considering this situation, the proposed vehicle EQ is a 10-band Graphical Equalizer with ISO center frequencies. After measuring the existing EQ apps, we found that the center frequencies are quite different according to apps, the gain responses are not accurate, even worse in the low bands, and various problems are in clipping processing. The proposed EQ has the entire structure consisting of a soft switch for preprocessing, an EQ main block, and a finalizer for post-processing which includes a DRC and a soft clipper along with methods for realizing accurate frequency responses according to EQ adjustments, a practical clipping algorithm that can be activated for saturated signals. In EQ user interfaces, storage buttons to save EQ values according to each audio source were provided for one click loadings and the whole frequency response curve display according to specific band gain adjustments with GEQ band sliders were provided for more accurate tuning.

“Position Dependent Amplitude Response in Automotive Loudspeakers” (60 mins)
Mark Ziemba – Panasonic

This Tutorial will review previous research in this area and how it audibly impacts the accuracy of music reproduction in automotive audio systems.

• New measurements on current loudspeakers that show difficulties in this area, and correspondingly some current loudspeakers that use specific design elements to overcome these anomalies.
• Live audible demonstrations of different loudspeakers that exhibit this AM distortion compared to others that have better performance. This performance will be monitored through the sound reinforcement system with video so every conference attendee can see the loudspeaker under test and experience the sound of the distortion with music examples.
• Some old and some new techniques will be used to make the distortion more audible to the attendees.
• Klippel linearity measurements on several these loudspeakers will be shown so we can isolate or eliminate the causes of these audible anomalies.
• Some conclusions will be offered and discussion entertained on loudspeaker design trade offs. How to optimize different measurable loudspeaker parameters for specific applications is always a valuable discussion topic and should be of interest to all audio engineers.

“Virtual Speaker Integration Through Simulation ” (60 mins)
Jeremy Charbonneu, Thibaud Costes, and Alexis Talbot – Hexagon

With the shift of vehicle manufacturing to rely heavily on a simulated design process, multiple iterations of prototype vehicles are no longer available. Finessing the fine details, such as the tuning of performance audio systems must therefore be completed on fewer vehicle builds as the components, mountings and materials are varied. Adding to this complexity is the reduced duration of the design window as the development time for new vehicles is getting shorter. Design engineers must be as efficient as possible in their efforts and use the best-in-class tools at their disposal; gaining insights earlier into their design process to make informed decisions.

This tutorial will aim to demonstrate an effective workflow for assessing sound system performance in an automotive compartment. This multi-stage novel approach utilizes a finite element method for developing the excitation boundary condition and the discontinuous Galerkin method (DGM) for propagating results within the vehicle cavity. The excitation pattern to be injected into the models will be based on a 1-Dimensional loudspeaker model which directly employs the Thiele and Small parameters of the loudspeaker supplier to transform an input voltage signal into a vibration of the speaker membrane. The final model compares the traditional absorption approach using an impedance boundary condition, to a workflow including 3-Dimentional DGM porous components within the treated cabin. To illustrate the compatibility between DGM techniques and GPU acceleration, a comparison has been performed using a single node with a single GPU that match runtime observed when using several high-performance computing nodes and hundreds of cores.