Sub-band Mixing and Addition of Digital Effects for Consumer Audio ELECTRICAL & ELECTRONIC ENGINEERING FINAL YEAR PROJECTS 2012/2013 Presented by Fionn O’Donohoe

Presentation headings Overview Project milestones Points of interest Filter design elements Future goals

Overview – What’s it for? Cost effective equaliser for consumer/pro audio Divides incoming signal into low, mid and high frequency bands. Two (or more) channel GUI. Allows maximum flexibility for user when manually altering gain.

Project Milestones Develop functionality for splitting, amplitude modification, and recombining audio using digital filters (Matlab). Investigate frequency domain approaches for carrying out the same task. Add a digital effect (e.g. reverb) to one or more channels. Translate signal processing functionality from the Matlab language into C/Java. Investigate implementation in real-time on a suitable platform, including wireless connectivity using Bluetooth.

Points of interest 1. Digital vs. FFT ◦ Computational complexity ◦ Spectral analysis of pre-stored data 2. Real-Time Wireless Connectivity ◦ Matlab translation into C or Java ◦ Max bandwidth for wireless transfer

Filter design elements IIR vs. FIR Filter parameters Group delay Spectrogram

Filter parameters IIR filter type chosen. Chebyshev Type 2.

Group delay Another “point of interest”. Original filter choice had noticeable delay.

Spectrogram Important tool for assessing frequency response.

Future goals FFT implementation Digital effect added Matlab file translation Real-time wireless connectivity

Questions