Digital signal processing methods to modify sound files to appear aged by imitating historical disturbances are reviewed. The opposite activity, audio restoration, has been cultivated during the past few decades to improve the sound quality of old recordings. Case studies of audio antiquing to render a music file to sound like a phonograph, gramophone, and LP recording are presented.

• Original audio signal A short piece of baroque music played on a harpsichord synthesizer: J. J. Froberger, Gigue, A minor, Suite no. 30

Simulation of degradations
• Signal bandwidth Simulation of the signal bandwidth of a phonograph recording.
• Distortion for soft passages The audio signal is distorted with the parameter B_soft = 2.
• Distortion for loud passages The audio signal is distorted with the parameter B_loud = 5.
• Total distortion The audio signal is distorted with the parameter B_soft = 2 and B_loud = 5.
• Pitch variation defect: wow Percentage of wow: 1.5%.
• Pitch variation defect: flutter Percentage of flutter: 2%.
• Pitch variation defect: wow&flutter Percentage of wow: 1.5%. Percentage of flutter: 0.5%.
• Hiss Synthetic phonograph hiss is added to the audio file. SNR = 5.6 dB
• Tracking errors Jump of the needle to the previuos groove, repeating the same part several times.
• Clicks Synthetic vinyl clicks are added to the audio signal
• Low frequency pulses (thumps) Synthetic thumps are added to the audio signal.

Case studies
• LP Disk Simulation
• Gramophone Simulation
• Phonograph Simulation