Loudness and Pitch

1. Loudness and Pitch • Be sure to complete the loudness and pitch interactive tutorial at … • http://facstaff.uww.edu/bradleys/courses/hs/psychophysics/pitch/loudnesspitch.html

2. Loudness • Subjective correlate of intensity • Normally use terms such as soft, comfortable, loud, softer, or louder, etc.

3. Scales • Sone Scale • Phon Scale

4. Sone scale • Used to measure the growth of loudness. • Based on a 40 dB SL, 1000 Hz reference • When a sound is twice as loud it is two sones, when it is four times louder than the reference it is four sones, etc. • In normal hearing people two sones is equal to about a 10 dB increase (50 dB SL). Every doubling of loudness yields an additional 10 dB SL in intensity increase.

5. Example of Sone Scale

6. Phon Scale • Based on concept of equal loudness contours • Used to measure loudness across frequencies.

7. Example of Phon Scale

9. Pitch • Subjective correlate of frequency • Normally use terms such as low pitch, high pitch, lower and higher pitch, etc.

10. Mel Scale • 40 dB SL 1000 Hz as a reference. • 1000 mels = 1000 Hz • Subjects are required to match increases in frequency with increases in pitch. • Research has shown that frequency rises at a higher rate than pitch. • What are the implications?

11. Growth of pitch

12. Mechanisms used to determine pitch • Determining pitch for periodic signals. • We use the fundamental frequency (fo). • We use the largest multiple of a group of component frequencies to determine fundamental. • Remember, that the lowest frequency does not always equal the fundamental. • e.g., if the component frequencies are 500, 550, 600 Hz, the fo is 50 Hz.

13. Mechanisms used to determine pitch • Determining pitch for aperiodic signals. • We use the center frequency. • E.g., a narrow band noise with a center frequency of 1000 Hz would have the same pitch as a pure tone of 1000 Hz, or a periodic signal with a fo of 1000 Hz.

14. Summary