Tape recorder effects on jitter and shimmer extraction

Area of Science:

• Acoustic analysis
• Signal processing
• Speech science

Background:

• Accurate acoustic analysis is crucial for speech pathology and research.
• Record/reproduce systems can potentially introduce distortions affecting analysis results.
• Understanding the impact of different recording formats on acoustic parameters is essential.

Purpose of the Study:

• To evaluate the accuracy of different tape recording formats for acoustic analysis.
• To determine the impact of record/reproduce systems on fundamental frequency, amplitude, jitter, and shimmer.
• To identify superior methods for minimizing data acquisition system contamination.

Main Methods:

• Five sine waves of fixed frequency and amplitude were directly sampled by a computer.
• Simultaneous recordings were made on four tape formats: audio reel-to-reel, FM reel-to-reel, audio cassette, and video cassette (PCM).
• Recordings and direct samples were analyzed for fundamental frequency, amplitude, jitter, and shimmer using a zero-crossing interpolation scheme.

Main Results:

• Distortion was negligible for average fundamental frequency and amplitude across all systems.
• Direct sampling and video cassette recorders (PCM) showed superior performance for jitter and shimmer estimation.
• FM recorders offered satisfactory results, while audio reel-to-reel was marginally adequate.
• Audio cassette recorders introduced significant jitter and shimmer, exceeding values reported for normal speech.

Conclusions:

• Direct sampling and video cassette recorders (PCM) are recommended for precise acoustic jitter and shimmer analysis.
• FM recorders provide a viable alternative, though with slightly reduced accuracy.
• Audio cassette recorders should be avoided for analyses requiring accurate jitter and shimmer measurements due to introduced distortions.