Audio Testing Laboratories

Visteon's audio testing laboratories provide objective measurements and documentation that significantly improve the subjective responses of in-vehicle audio listeners.

Objective Measurements
Although our audio engineers work towards the ultimate goal of constantly improving listeners' subjective responses, the majority of our testing is based on objective criteria. By focusing upon scientific measurements and documentation, we can deliver the best quality to the widest range of audio systems and vehicle types.

Speaker Testing
Visteon's audio laboratories feature hemi-anechoic chambers, sound-insulated rooms that eliminate echoes and reverberations when testing speakers. By eliminating echo and reverberation, the true acoustic performance of a speaker can be measured.

Visteon's speaker tests measure three parameters:

Frequency Response – A measurement of how accurately a speaker reproduces each frequency within the range of human hearing.

Total Harmonic and Inter-Modulation Distortion – By measuring non-linearity, we can prevent the speaker from distorting and adding tones that aren't in the original recording.

Cone Displacement and Offset Tracking – This Visteon-developed test uses a laser-based measurement of speaker cone movement to diagnose and correct speaker design issues.

In order to isolate any potential issues, the speaker chambers allow the speaker's acoustic performance characteristics to be quantified before they are placed in the vehicle cabin for system-level measurements.

Systems-Level Testing

Using a six-microphone measurement array, Visteon engineers measure the effects of different interior materials, components and road noise on audio system quality to understand how interior space affects listener satisfaction with audio system performance.

A variety of tests measure the acoustic and electrical parameters of the entire audio system in the vehicle:

• In-Vehicle Acoustic Frequency Response – Assesses the acoustic response of the system at a listener's ears position.
• Acoustic Sensitivity – A measurement of system volume (in decibels Sound Pressure Level) at 10 percent acoustic distortion.
• Acoustic Polarity – Tracks the movement of a speaker cone for directional consistency.
• Electrical Clipping Voltage – Measures the power delivered to the speakers in the vehicle and any potential losses that may occur in wiring harnesses and connectors.
• Electrical Frequency Response –- Measures the electrical signal going from the amplifier or headunit to the speakers.
• Electrical Noise Floor – Measures the amount of speaker hiss when system volume is reduced.

This data enables us to optimize the equalization (EQ) settings of an audio system for a particular vehicle environment and compensate for any acoustic anomalies within the vehicle cabin.

Subjective Sound Qualities Imaging The positioning of separate sound elements. Often referred to as the "soundstage." Ambience An aural sense of the space in which the recording was made.

Blind A/B Jury Testing

In order to assess imaging and ambience, Visteon uses a subjective listening process based upon objectivity that can accurately compare the subjective parameters of different audio systems.

Conducted with trained listeners, these tests are referred to as "Blind A/B Tests." The test methodology, which keeps the listeners from knowing what system they're hearing, eliminates the listener bias that makes such experiments difficult. With precise recordings that recreate audio system performance, including the imaging and ambience, listeners rate quality on a scale of 1 to 5, without knowing the type of vehicle or system being tested.

Visteon has documented a 98 percent satisfaction correlation between customer response and test method measurements.

Additional Information
Product Specifications - Digital Signal Processing System
Feature Story - Optimizing In-Vehicle Audio
Feature Story - DSP Improves Vehicle Radio Reception
Feature Story - Audio Systems Testing
Feature Story - Systems-Level Testing Provides Quality Audio