1 / 22

Complex Auditory Stimuli

Complex Auditory Stimuli. Complex periodic waves Complex aperiodic waves. Complex Periodic Waves. Addition of sine waves See next slide for examples Always repeat themselves over time … and therefore have a period. Always have a fundamental frequency

aolani
Télécharger la présentation

Complex Auditory Stimuli

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Complex Auditory Stimuli • Complex periodic waves • Complex aperiodic waves

  2. Complex Periodic Waves • Addition of sine waves • See next slide for examples • Always repeat themselves over time • … and therefore have a period. • Always have a fundamental frequency • Fundamental is the largest common denominator of a group of component frequencies • Always have harmonic frequencies • Harmonics are are whole number multiples of the fundamental • e.g., 1f, 2f, 3f, etc.

  3. Periodic Complex Waves

  4. Periodic Complex Waves

  5. Periodic Complex Waves

  6. How are complex periodic waves displayed? • Waveform • Amplitude Spectrum (line spectrum)

  7. How are complex periodic waves displayed? • Several examples of a line spectrum. The lower figure represents the vowel / i /.

  8. Fundamental Frequency • See earlier slide. Largest common denominator of a group of component frequencies. • E.g., If the the component frequencies are 500, 550, 1000, 1050, the largest number that can be evenly divided would be 50. Therefore, 50 Hz would be the fundamental. • It would also have the same pitch as a 50 Hz tone.

  9. Harmonics • Harmonics are whole number multiples of the fundamental (fo). The fundamental is always the first harmonic (1f). • May be determined by dividing the fo into the component frequency. • In the previous example the component frequencies would equal the following harmonics. • 500 Hz = 10xf (i.e., 10th Harmonic) • 550 Hz = 11xf • 1000 Hz = 20xf • 1050 Hz = 21xf

  10. Harmonics • Relationship between harmonics and overtones. • Overtones are a musical term and are related to harmonics.

  11. Complex Aperiodic Waves • Frequencies are random • Do not repeat over time • Do not have a fundamental frequency • Do not have harmonics

  12. How are complex aperiodic waves displayed? • Waveform • Amplitude spectrum (continuous spectrum)

  13. How are complex aperiodic waves displayed?

  14. How is Sound Analyzed? • Spectrogram (aka sonogram) • Sound level meter • Oscilloscope and frequency counter • Fourier and real time analyses

  15. Spectrogram

  16. Sound Level Meter

  17. Sound Level Meter • Sound Pressure Level (linear) • dBA, dBB, dBC (weighted scales)

  18. Sound Level Meter • dBA, dBB, dBC (weighted scales) • Used primarily for industrial, community, and aviation applications. • dBA scale has greatest amount of attenuation in low frequencies. • dBB scale somewhat inbetween dBA and dBC. • dBC scale has least amount of attenuation in high frequencies.

  19. Other Methods of Analysis • Oscilloscope (displays waveform)

  20. Other Methods of Analysis Frequency Counter

  21. Other Methods of Analysis • Fourier Analysis • A method of mathematically changing a waveform to an amplitude spectrum • Real Time Analysis or Fast Fourier Transform (FFT). • Fourier analysis in real time

  22. Summary

More Related