Psychoacoustics Exam 4

Psychoacoustics Exam 4 Define Equal Loudness Levels and How do we determine them? - ANS - By definition, when one refers to the loudness level of a sound, one is comparing the loudness of that sound with the loudness ...

Psychoacoustics Exam 4 Define Equal Loudness Levels and How do we determine them? - ANS - By definition, when one refers to the loudness level of a sound, one is comparing the loudness of that sound with the loudness of a 1000 Hz tone. Loudness level is measured in units called phons. By definition, the loudness level of a sound in phons is equal to the dB SPL of a 1000 Hz tone judged equally loud. 20 phons is the loudness of a 1000 Hz tone at 20 dB SPL and the loudness of any other frequency sound that is perceived equally loud. A sound of 40 phons has the same loudness as 1000 Hz at 40 dB SPL. A sound that is 80 phons is as loud as 1000 Hz at 80 dB SPL, and so forth. An equal-loudness curve (contour) connects points of equal loudness across frequency. Fletcher-Munson curves Iso-loudness curve Phon curve Why do we use loudness scales as opposed to loudness levels? - ANS - Loudness level indicates equal loudness, but not how much louder one sound is compared to another sound. A loudness scale indicates the relative loudness of sounds. We are not only interested in the loudness of a particular sound, but also in how much louder one sound is than another. Define the following terms: Phon and Sone What is the difference between them? - ANS - The phon is the unit of loudness level. All sounds that are equal in phons have the same loudness level even though their physical magnitudes may be different. The unit of loudness is called the sone. One sone is the loudness of a 1000-Hz tone presented at 40 dB SPL. Since sound pressure level in decibels and loudness level in phons are equivalent at 1000 Hz, we may also define one sone as the loudness corresponding to a loudness level of 40 phons. Temporal Integration is observed for loudness. Talk about this phenomenon - ANS - Sensitivity improves as signal duration increases up to about 200 to 300 ms, after which thresholds remain essentially constant. A similar phenomenon is also observed for loudness. Increase in loudness is greater for increases in duration up to about 80 ms, and then tends to slow down. There is an increase of loudness as duration is increased up to some "critical duration," and loudness growth essentially stops with added duration. Describe Loudness Adaptation - ANS - It refers to the decrease in the loudness of a signal that is continuously presented at a fixed level for a reasonably long period of time. The signal appears to become softer as time goes on even though the sound pressure level is the same. What is the difference between annoyance and Noisiness? - ANS - Noisiness is often used to describe the objectionability or unwantedness of a sound. It is not related to the meaning or implications of the sound. Noisiness has to do with the physical parameters of the noise. The annoyance describes the objectionability of a sound involving such things as: (in addition to its physical parameters) The sound's meaning or interpretation Implications for the listener Novelty of the sound The source of the noise The individual's noise susceptibility. For example, residential noise annoyance appears to be affected by concerns about the dangers. Since the same sound pressure level is associated with different loudness levels as a function of frequency, it is convenient to have frequency-weighting scales. Describe the three loudnessbased weighing scales discussed in class. - ANS - The A-weighting approximates the general shape of the 40-phon curve by de-emphasizing the low frequencies and more efficiently passing the high. The B-weighting roughly corresponds to the 70-phon loudness level. The C-weighting mimics the essentially flat response of the ear at high loudness levels. Following hearing aid fitting, how would you verify the return to normal loudness perception in the clinic? Describe three methods (or options). - ANS - Judgments in the sound booth Contour Test of Loudness Listeners judge the loudness of sounds presented in the sound field using a seven category loudness growth scale to determine the sound level required for each one of these categorical levels for a given listener. Profile of Aided Loudness (PAL) A subjective outcome measure of loudness. It is the only measure currently available that is designed specifically to assess aided loudness perception in daily life. Includes 12 environmental scenarios, 3 for each category, soft, moderate and loud (e.g., own breathing, electric razor, door slamming). Listeners are asked to rate each scenario in two different scales, one for loudness and one for satisfaction of that loudness rating. Patient interview How do things sound? An equal loudness contour connects points of equal loudness across frequency. Equal loudness contours are also termed _________ curve. - ANS - phon The unit of equal loudness is the ________. it references loudness to SPL of a __________ Hz tone. - ANS - phon / 1000 Relative loudness, where the listener attaches a number to loudness, doubling the number if the loudness doubles, is a description of the ________ scale. - ANS - sone Loudness grows more quickly for ______ frequency sounds. - ANS - low The unit of loudness level is _______, whereas the unit of loudness is ________________. - ANS - phon / sone A tone that is as loud as a 1000-Hz tone at 50 dB has a loudness level of _____ phons. - ANS - 50 At low loudness levels, the phon curves are quite similar in shape to the _____________ curve. - ANS - minimum audible field (MAF) Fletcher-Munson Curves - ANS - Iso-loudness Curves - ANS - Phon Curve - ANS - True/False: The loudness of sound only depends on sound intensity - ANS - False True/False: The reference point for the phon scale is 2000 Hz - ANS - False True/False: Loudness in sones is always a straight line when plotted as a function of sound level. - ANS - False True/False: Sone Function become steeper at lower stimulus levels, indicating faster loudness growth. - ANS - True True/False: Loudness of two tones stays the same about as long as tones are separated by less than the critical bandwidth. - ANS - True True/False: Sounds may be experienced as objectionable regardless of their intensities. - ANS - True True/False: The perception of intensity is called pitch. - ANS - False T/F: Intensity and loudness are the exact same thing - ANS - False T/F: The phon curves tend to become flatter for higher loudness levels - ANS - True T/F: The lower frequencies grow in loudness at a faster rate that the higher frequencies. - ANS - True