Alc Tuning Guide; Introduction; Overview - AMS AS3460 User Manual

7

ALC Tuning Guide

7.1

Introduction

The ams adaptive noise cancellation algorithm Active Leakage Compensation (ALC) is more complex
than static ANC algorithms and requires the tuning of several filters and parameters. Luckily, there is
no DSP programming or scripting required, because everything can be configured graphically within
the ams Flex tool. The Flex tool provides a graphical interface for filter tuning, simulation, parameter
setting and everything else there is to configure on AS3460. This tutorial shows the recommended
design flow for configuring AS3460's ALC algorithm for a new earphone model.
Note: Only some concepts of operating Flex and the AS3460 evaluation kit are introduced here.
Please also read the Flex manual and the evaluation kit handbook.
7.2

Overview

The whole, complex ALC algorithm can be split in several sections and sub-algorithms: there is the
basic feed forward ANC adaption, a feedback ANC adaption derived from the feed forward adaption,
the music compensation and adaption in the presence of music as well as several support algorithms
for monitoring stability and other corner cases.
To handle this complexity, we recommend to follow a certain order when tuning the ALC algorithm:
1. Careful review and calibration of measurement data
2. General system configuration
3. Static tuning of feed forward ANC for the lowest leakage
4. Tuning of high leakage feed forward ANC
5. Feed forward only adaption and stability testing
6. For some headphones: Extra low frequency shelf
7. Design of feedback filters
8. Feedback filter performance and stability testing
9. Tuning of music compensation filters
10. Music compensation verification procedure
11. Testing and tuning of corner cases and algorithm parameters
Demo Kit Manual • PUBLIC
UG000480 • v3-00 • 2021-Nov-08
Document Feedback
AS3460
ALC Tuning Guide
│ 66
126