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Loudness and Pitch

• Be sure to complete the loudness and pitch interactive tutorial at …• http://facstaff.uww.edu/bradleys/courses/hs/psy

chophysics/pitch/loudnesspitch.html

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Loudness

• Subjective correlate of intensity• Normally use terms such as soft,

comfortable, loud, softer, or louder, etc.

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Scales

• Sone Scale• Phon Scale

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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.

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Example of Sone Scale

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Phon Scale

• Based on concept of equal loudness contours

• Used to measure loudness across frequencies.

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Example of Phon Scale

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Pitch

• Subjective correlate of frequency• Normally use terms such as low pitch, high

pitch, lower and higher pitch, etc.

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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?

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Growth of pitch

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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.

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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.

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Summary