On Road Vehicle Measurements (road noise, ANR, noise reduction etc.)
On road Audio Measurements using SoundCheck and AudioConnect 2
Introduction to Road Noise, ANR, ANC and other In-Cabin Measurements
It is often necessary to make audio measurements in a car while driving, for example for evaluating road noise and noise reduction systems. Applications include:
- Road noise measurements
- Evaluation of active road noise reduction systems/ car noise cancellation systems
- Evaluation of infotainment system characteristics that may change with background noise such as frequency response
- Hands free communications systems in real-world conditions such as POLQA measurements.
Equipment for In-Cabin Car Audio Measurements
Head and Torso Simulator for in-cabin audio measurement (photo courtesy of Brüel & Kjær)
Typically, on road in-car audio measurements (or simulated on-road vehicle audio measurements), are made using microphones or a head and torso simulator placed in the front driver or passenger seat (where the driver is in the driver seat). The microphones are connected via an audio interface to an audio analyzer such as the software-based SoundCheck.
SoundCheck is a modular software-based audio analyzer that can be configured with up to 64 channels. It communicates with automotive infotainment systems via A2B bus, Bluetooth and USB drive. It’s capabilities include a wide range of in-car measurements including frequency response, Max SPL, Buzz, Squeak and Rattle (BSR), road noise measurements, evaluation of active road noise reduction (ANR) systems, infotainment and communications systems and more.
Where only 2 channels of audio input are needed, the AudioConnect 2 is ideal for in-car measurements. It is the first USB powered audio interface, with a single USB-C connection to your laptop providing both power and data transmission. This makes it extremely portable and simple to configure since no additional power or cabling is required. It powers both ICP and IEPE microphones and supports TEDS, making it compatible with most measurement microphones and head and torso simulators. For higher channel counts, the AmpConnect 621 provides 6 powered input channels, ideal for use with a 6 microphone array. This interface requires power, but also features an amplifier, impedance measurement and more. Both interfaces offer high resolution input
Other testing accessories typically include a head and torso simulator or measurement microphones, often in a 6-microphone array. A Bluetooth interface is also required if this method is chosen to interface with the head unit.
Test Configurations for On Road Audio Measurements
There are many possible SoundCheck configurations for measuring road noise and active noise cancellation / active road noise reduction while driving. Here are some examples:
Setup for recording road noise in a car using two microphones attached near the driver’s ears. This is particularly useful when the driver needs to make measurements in the drivers seat while driving! Microphones may be attached to a hat as shown in the photo above (a budget HATS!)
Setup for recording road noise in a car using a head and torso simulator.
SoundCheck with a 6-microphone array for measurement of road noise and active road noise cancellation.
Video Demonstrations of Active Road Noise Cancellation Measurement
Video coming soon!
SoundCheck Test Sequences for Active Road Noise Cancellation Measurement
Test sequence for road noise measurement and active road noise cancellation evaluation coming soon.
