Date post: | 28-Mar-2015 |
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An Approach in Reproducing the Auto-
Tune Effect
Mentees: Dong-San Choi & Tejas Rawal Mentor: David Jun
Overview
• Quick introduction to Auto-Tune• Methodology in recreating the Auto-
Tune effect• Application
What is Auto-Tune?
• First created by Andy Hildebrand• Corrects out-of-tune human sung
pitches or instruments• How? Autocorrelation & Phase Vocoder• Demo using “I Am T-Pain”
Methodology
Can be broken into two parts:1) Pitch Detection
- Autocorrelation2) Pitch Shifting
- Phase Vocoder
Pitch Detection
• There are many different approaches to estimate the pitch of a periodic signal
• We used the autocorrelation function to determine the fundamental frequency of our speech signal
• Autocorrelation refers to the correlation of a time series with its own past and future values.
• It compares a segmented section of a speech signal (human voice) with another segment from the same signal and calculates the time separation between them. Autocorrelation is a mathematical tool that helps find repeating patterns, such as: – A periodic signal which has been buried under noise – The fundamental frequency in a signal implied by
its harmonic frequencies.
A Visual Representation
Pitch Shifting
• Pitch – 12 pure notes in an octave• Each note corresponds to a
frequency• “In-tune” notes • “Out-of-tune” notes• Pitch shifting in Auto-Tune
- use of a phase vocoder
The Phase Vocoder
Use - to obtain a digital representation of speech
Application - can modify basic speech parameters to
permit alteration of time or frequency dimensions of a speech signal
The Phase Vocoder
So…Inputs <= speech signalOutputs <= magnitude & phase
What can we do with these parameters?
Our Approach
Application• Auto-tune is a audio
processing system use to enhance a singer’s vocal performance
• Auto-tune uses a phase vocoder unit to correct pitch and disguise vocal mistakes
• Many famous artists such as T-Pain and Kanye West currently use Auto-tune to perfect the vocals on their tracks
Thank You for your Time!
Special thanks to the PURE program for the opportunity and our mentor, David Jun
Any Questions/Comments?