Loudness Judgments Research Articles

Lead stimulation effects on reflex blink, exogenous brain potentials, and loudness judgments.

Prepulse inhibition of the reflex blink by a weak stimulus shortly preceding a blink-eliciting stimulus has been described as a sensorimotor gating phenomenon that may protect processing of the first stimulus. To determine how a stimulus configuration that elicits prepulse inhibition also affects exogenous evoked potentials and perceived loudness of the paired stimuli, the three types of response were recorded simultaneously under four conditions: tone pairs of 75-110 dB and 75-75 dB and single control tones of each intensity. Two studies using different intrapair intervals found that blinks and exogenous potentials peaking after 50 ms were smaller for the second tone of pairs than for equal-intensity single tones. Pairing also reduced the loudness of 110-dB second tones, but the loudness of 75-dB first and second tones was unaffected or increased. These effects are discussed in terms of parallel processing of transient, unmodulated information in specific paths, steady-state modulated information in nonspecific paths, and a context-dependent effect on loudness judgments.

Contextual processing of multidimensional and unidimensional auditory stimuli.

Stimulus context (the distribution of stimulus values) can strongly affect both perception and judgment. In 14 experiments, the method of magnitude estimation revealed 2 fundamentally different kinds of context effect in loudness. An assimilative effect dominated when stimuli varied unidimensionally (in intensity only). But a contrasting, or adaptation-like, effect dominated when stimuli varied multidimensionally (in frequency and intensity). In Experiment 15, direct loudness comparison revealed a potent, adaptational process specific to the signal frequency. Taken together, these and other results are compatible with the view that loudness perception and judgment reflect the net outcome of 2 different contextual processes: a relatively early (though probably not peripheral) process of perceptual adaptation and a later process of response-dependent assimilation.

Loudness Judgment Procedures for Evaluating Hearing Aid Preselection Decisions for Severely and Profoundly Hearing-Impaired Listeners

Hearing aid fitting involves a two-phase process of preselection and evaluation (Seewald RC and Ross M. Amplification for the Hearing Impaired 1988:213-271). The purpose of the present study was to examine alternative procedures that clinicians might use in the evaluation phase to verify the adequacy of hearing aid preselection decisions for severely and profoundly hearing-impaired listeners. Bekesy tracking, loudness rating, and conventional bracketing procedures were used to determine threshold, most comfortable listening level, and uncomfortable listening level for 10 hearing-impaired young adults. Stimuli were pulsed pure tones of 500, 1000, and 2000 Hz and filtered words. Means and standard deviations of most comfortable listening levels and uncomfortable listening levels derived from loudness judgments of the 10 subjects showed only nominal differences across procedures. However, correlation analysis (Pearson r) indicated that individuals responded to the three procedures in varying ways, producing different loudness judgments and overall dynamic ranges. Thus, test procedure may influence the clinician's final evaluation of a preselected hearing aid. Initial work suggests that closed-set response categories such as loudness rating can limit measurement variability and potentially guide the clinician's evaluation of hearing aid preselection decisions.

Audiovisual investigation of the loudness-effort effect for speech and nonspeech events.

There is some evidence that loudness judgments of speech are more closely related to the degree of vocal effort induced in speech production than to the speech signal's surface-acoustic properties such as intensity. Other researchers have claimed that speech loudness can be rationalized simply by considering the acoustic complexity of the signal. Because vocal effort can be specified optically as well as acoustically, a study to test the effort-loudness hypothesis was conducted that used conflicting audiovisual presentations of a speaker that produced consonant-vowel syllables with different efforts. It was predicted that if loudness judgments are constrained by effort perception rather than by simple acoustic parameters, then judgments ought to be affected by visual as well as auditory information. It is shown that loudness judgments are affected significantly by visual information even when subjects are instructed to base their judgments only on what they hear. A similar (though less pronounced) patterning of results is shown for a nonspeech "clapping" event, which attests to the generality of the loudness-effort effect previously thought to be special to speech. Results are discussed in terms of auditory, fuzzy logical, motor, and ecological theories of speech perception.

Slippery context effect and critical bands.

This article explored the slippery context effect: When Ss judge the loudness of tones that differ in sound frequency as well as intensity, stimulus context (relative intensity levels at the 2 frequencies) can strongly influence the levels that are judged equally loud. It is shown that the size of the slippery context effect depends on the frequency difference between the tones: Small frequency differences (less than a critical bandwidth) produced essentially no slippery effect; much larger differences produced substantial effects. These results are consistent with a model postulating the existence of a central attentional or preattentive "filter-like" process whose weighting coefficients represent the size of the absolute as opposed to the relative (contextual) component of loudness perception and judgment.

Stimulus context and absolute magnitude estimation: A study of individual differences

The effect of stimulus context on absolute-magnitude-estimation (AME) judgments was examined by determining whether the loudness judgment of a tone is influenced by the intensities of other tones presented within the session. A group of 18 subjects was tested in separate sessions in which they judged stimuli within either a low (10-60 dB SL) or a high (40-90 dB SL) range of intensities. Examination of the results of individual subjects revealed that judgments of stimuli common to the two ranges were, in most subjects, unaffected or only slightly affected by the position of the range. The judgments of 2 subjects who failed to follow the instructions, however, showed very large context effects due to changing the stimulus range. The results of a second experiment, in which 22 subjects judged the loudness of tones within either a narrow (35-65 dB SL) or a wide (20-80 dB SL) range, revealed that, in all but 1 subject, the width of the range had no systematic effect on the loudness judgments of stimuli common to both ranges. This was also true 1 month later when 16 of the subjects returned to the laboratory to judge the loudness of tones within an even wider range of 10-90 dB SL. It was concluded that AME judgments are relatively insensitive to the potential biasing influences of stimulus context.

Some aspects of time, stimulus complexity, and gender in 40‐Hz EEG responses

The present study investigated 40‐Hz EEG responses of 17 listeners who received ipsilateral and contralateral story and click stimuli. An initial comparison between loudness adaptation and 40‐Hz activity failed to show any change in central activity corresponding to change in loudness judgments. For the complete sample of listeners, a significant interaction was found between stimulus complexity, ear, and 40‐Hz response quadrant. Subsequent investigation of gender differences across the temporal region suggests an extension of conclusions offered recently by Kimura. Implications will be discussed.

Variability of the slope of the loudness function in normal and impaired hearing

The variability of the slope of the loudness function was determined within and across groups of people with normal and impaired hearing. Slope values were obtained from magnitude estimation and production of loudness and from cross‐modality matching and magnitude estimation of apparent length. Loudness judgments were made for 1‐s tone bursts at a frequency in the 500‐ to 2000‐Hz range by more than 30 people from the general population with normal hearing in the midfrequency region. Twenty people also judged loudness at three frequencies in the same ear, two in the region of impaired heating and one in the region of normal hearing. Over a wide stimulus range, the relation between loudness and sound pressure for normal hearing was a power function with a slope in log‐log coordinates close to 0.60. Both the means and standard deviations of the slopes increased with the degree of hearing loss. These results are compared to those reported in a current paper [R. P. Hellman and C. H. Meiselman, J. Acoust. Soc. Am. 88 (in press)] for five different groups, one with normal hearing and four with noise‐induced cochlear impairments. [Work supported by the Rehabilitation Research and Development Service of the VA.]

The loudness of sounds that increase and decrease continuously in level

A sound at a low level is heard as much softer after having decreased continuously from higher levels than if presented after a period of silence at that same low level. Canévet [Acustica 61, 256-264 (1986)] demonstrated this phenomenon for a tone that (1) decreased from 65 to 20 dB in 180 s; he also presented a tone that (2) increased from 20 dB, or (3) was presented as pairs of bursts at various levels in random order. Below about 40 dB, loudness changed most rapidly in the decreasing condition so that, at 20 dB, the tone was judged ten times softer than in conditions (2) and (3). In the present experiments, magnitude estimation was used to examine the possible role of judgmental biases and adaptation in this rapid loudness decline, which we call decruitment. Results show that decruitment did not come about because subjects made many successive loudness judgments; loudness declined as much when a tone was judged only twice, at the beginning and end of its 180-s decrease. In contrast, interrupting the decreasing tone so that it was heard only at 70 dB and 160 s later at 30 dB greatly diminished the decruitment. Similarly, pairs of 500-ms tone bursts presented at successively lower levels instead of continously decreasing did not show decruitment, suggesting that sequential biases are irrelevant. The likely cause of decruitment is sensory adaptation.

Does stimulus context affect loudness or only loudness judgments?

Marks (1988) reported that when equal-loudness matches were inferred from magnitude estimates of loudness for tones of two different frequencies, the matches were affected by changes in the stimulus intensity range at both frequencies. Marks interpreted these results as reflecting the operation of response biases in the subjects' estimates; that is, the effect of range was to alter subjects' judgments but not necessarily the perception of loudness itself. We investigated this effect by having subjects choose which of two tone pairs defined the larger loudness interval. By using tones of two frequencies, and varying their respective intensity ranges, we reproduced Marks' result in a procedure devoid of numerical responses. When the tones at one frequency are all soft, but the tones at the other frequency are not all soft, cross-frequency loudness matches are different from those obtained with other intensity range combinations. This suggests that stimulus range affects the perception of loudness in addition to whatever effects it may have on numerical judgments of loudness.

Frequency response of headphones measured in free field and diffuse field by loudness comparison

Coupler measurement of headphone frequency response may be incorrect at high and low frequencies [T. Hirahara and K. Ueda, J. Acoust. Soc. Am. Suppl. 1 87, S142 (1990)]. Since sound pressure near the eardrum is difficult to measure physically, a psychophysical method was employed to assess real ear frequency response of headphones. Loudness comparisons were performed by four subjects, under two experimental conditions: free field (anechoic room) and diffuse field (reverberation room). These conditions were run to check the influence of field characteristics on the reliability of the measurements. Each subject adjusted the headphone level of critical band noise bursts until they were equally loud as those from a reference loudspeaker (7 dB SPL). Measurement scatter was smaller in the diffuse field than in the free field. One hypothesis to explain this result is that head movement causes less change in level in a diffuse field than in a free field. Support for this comes from measurement of the SPL distribution in the two rooms, which revealed that the sound-pressure variation was smaller in the diffuse field than in the free field. To examine the reliability of loudness judgments at high frequencies, another method—hearing thresholds by Békésy tracking—was employed. Each subject's threshold was measured with both loudspeakers and headphones. After compensation was made for loudspeaker transfer functions, headphone frequency response was deduced from the results. This method led to high-frequency responses similar to those from loudness comparison. Below 6 kHz, however, there were only slight differences, because equating loudness for loudspeaker sound and for headphone sound does not strictly correspond to equal sound pressure at the eardrum.

On the judgment of loudness, noisiness and annoyance with actual and artificial noises

Loudness, noisiness and annoyance were judged for 36 stimuli by Japanese and German subjects. In experiment 1, actual noises such as aircraft and road traffic noise were used. In experiment 2, artificial noises were used. Their level patterns were simulated to correspond to the actual sound sources used in experiment 1, and the carrier was pink noise. Absolute magnitude estimation was used for making judgments. Eight German subjects and eight Japanese subjects participated. Judgments of loudness, noisiness and annoyance were made for actual and for simulated sounds. Results showed the following. (1) The concepts “loudness”, “noisiness” and “annoyance” have rather different implications; various factors, such as the temporal pattern of the stimulus, frequency components, duration and subjective meaning, contribute to the differences. (2) Differences in the subjective meaning of sounds may have an important effect on judgments of noisiness and annoyance. (3) German subjects seem to be more sensitive to level fluctuation; they tend to judge sound on the basis of its maximum level, whereas Japanese do so on the basis of its energy. (4) In the case of traffic noise, there was little difference in the evaluation of the three aspects by the German and Japanese subjects; it therefore seems appropriate to evaluate these sounds by L A eq .

Judgments and measurements of the loudness of tinnitus before and after masking.

This study explored the relation between changes reported in the perception of the loudness of tinnitus after noise exposure and changes measured in matches to the loudness of tinnitus after noise exposure. Preexposure assessment of the loudness of tinnitus was followed by monaural exposure to wide-band Gaussian noise (for a 5-min period), after which a pulsed, 200-ms tone was presented either ipsilateral or contralateral to the exposed ear. Following each noise exposure, the subject (a) judged the change in the pre- and postexposure tinnitus strength and (b) compared the loudness of the postexposure tinnitus to that of the pure tone. By combining data across noise exposures, a measure of the postexposure tinnitus magnitude was computed. For three of six subjects, the pre- and postexposure magnitude did not differ significantly even though the judgments indicated that the pre- and postexposure loudness of the tinnitus had changed. These data raise the possibility that some loudness judgments reflect variability in the tinnitus rather than the effect of the noise on the tinnitus.

An audiovisual investigation of the loudness/effort effect for speech and nonspeech events

There is some evidence that loudness judgments of speech are more closely related to the degree of vocal effort induced in speech production than to the speech signal's surface acoustic properties, such as intensity [P. Ladefoged and N. P. McKinney, J. Acoust. Soc. Am. 35, 454–460 (1963)]. Other researchers have claimed that speech loudness can be rationalized by considering simply the acoustic complexity of the signal [R. D. Glave and A. C. M. Reitveld, J. Acoust. Soc. Am. 58, 875–879 (1975)]. Since vocal effort can be specified optically as well as acoustically, a study to test the effort‐loudness hypothesis was conducted that used conflicting audiovisual presentations of a speaker producing CVs with different efforts. The prediction was made that if loudness judgments are based on effort perception rather than on simple acoustic parameters, then judgments should be affected by visual as well as auditory information. It is shown that loudness judgments are significantly affected by visual information even when subjects (1) are instructed to base their judgments on only what they hear and (2) cannot detect a discrepancy between the audio and visual components. Moreover, the same results are shown for a nonspeech “clapping” event attesting to the generality of the loudness‐effort effect previously thought to be special to speech

Selecting Hearing Aid Gain and Frequency Response Characteristics Based on a Comparison of Loudness Judgments and POGO

Selecting Hearing Aid Gain and Frequency Response Characteristics Based on a Comparison of Loudness Judgments and POGO

Loudness judgments in recruiting ears as influenced by intensity, and interspersed changes in intensity

It has been found that loudness judgments adapt to monaural stimulus increments [E. M. Weiler, D. E. Sandman, and L. M. Pederson, Brit. J. Audiol. 15, 201–204 (1981)]. The present study was undertaken to determine whether the changes in high‐frequency recruiting ears measured at a nonrecruiting frequency (1000 Hz), were the same as in normal listeners. Both groups showed a similar decline in judgment to the baseline 660‐dB tone. There was a significant interaction between groups, intensity, pulsed duration of an interspersed 10‐dB increment, and successive judgments of loudness. Similar interactions were seen at 20 dB above the baseline intensity.

A method for relating loudness-matching and intensity-discrimination data.

A method that allows direct comparisons between pure-tone loudness-matching and intensity-discrimination data in normal and hearing-impaired listeners is described. This method makes a minimal number of assumptions about the relations between loudness perception and intensity-discrimination performance. Loudness is considered to be related to overall, perceived stimulus magnitude and intensity-discrimination performance is considered to reflect the accuracy with which a loudness judgment can be made. Because pure-tone intensity-discrimination performance varies as a function of stimulus level in normal ears, the standard level required to produce a particular difference limen in an impaired ear can be inferred from normal-ear intensity-discrimination data. Thus, plotting standard levels yielding normal difference limens as a function of standard levels yielding the equivalent sized difference limens from a threshold-shifted ear produces a function directly comparable to loudness recruitment functions. If loudness-growth and intensity-difference limens were tightly coupled in threshold-shifted ears, then stimuli that yield equal size difference limens would be equally loud. This relation was tested by obtaining loudness-matching and intensity-discrimination data from normal-hearing listeners with thresholds shifted by a wideband noise and hearing-impaired listeners with cochlear-type hearing losses. The results from these listeners show similarities between the traditional loudness-recruitment functions and "intensity-recruitment" functions derived from the assumed relation between the two measures. The primary difference between the functions is at low and moderate sensation levels where loudness grows at a more rapid rate than the difference limen.

Auditory sensory storage in relation to the growth of sensation and acoustic information extraction.

A brief, vivid phase of auditory sensory storage that outlasts the stimulus could be used in perception in two ways: First, all of the neural activity resulting from the stimulus, including that of the sensory store, could contribute to a sensation of growing loudness; second, the sensory store could permit the continued extraction of information about the sound's acoustic properties. This study includes a task for which these two processes lead to different predictions; a third prediction is based on the two processes combined. The task required loudness judgments for two brief tones presented with a variable intertone interval. The results of Experiments 1-3 were as one would expect if both the growth of sensation and information extraction contributed to the pattern of loudness judgments. Experiment 4 strengthened the two-process account by demonstrating the separability of the two processes. Approaches to mathematical modeling of these results are discussed.

Remembrance of sounds past: Memory and psychophysical scaling.

What is the role of long-term memories of previous stimulus-response mappings, and of previous sensory and perceptual experiences generally, in psychophysical scaling judgments? I conducted four experiments in an attempt to provide some preliminary answers to this question. In each experiment, subjects made judgments of the loudness of sounds on 3 successive days. Stimulus intensities were drawn randomly from the same set on Days 1 and 3 but from a different set, either all 12 dB higher or all 12 dB lower, on Day 2. Four different types of psychophysical scaling judgments were studied: category judgment without an experimenter-induced identification function, ratio magnitude estimation with a variable standard, absolute magnitude estimation, and cross-modality matching. The first two methods required completely relative judgment, the last two completely absolute judgment. Data from all methods reveal profound effects of stimulus-response mappings experienced on previous days (long-term memory) and immediately previous stimuli and responses (short-term memory) on responses to current stimuli. Responses were typically a compromise between absolute and relative judgment. Individual differences were dramatic.

Spike-rate intensity functions of cat cortical neurons studied with combined tone-noise stimuli.

In the auditory cortex of anesthetized cats, single neurons were studied for their sensitivity to tones presented against backgrounds of continuous wide-spectrum noise. Tone pulses and noise stimuli were mixed acoustically and presented using calibrated, sealed stimulating systems. Data collected were spike-rate intensity functions for tones delivered alone and in the presence of noise. In most neurons, noise of any given intensity induced tone sensitivity shifts that were greatest for frequencies to which the neurons were most sensitive. When the sensitivity loss was in excess of about 15 dB, continuous noise usually caused a steepening of the slope of the tone intensity function. These data suggest that the excitatory response area of a cortical neuron is shaped by multiple, incompletely overlapping inputs of varying sensitivities. In the presence of a continuous noise mask, the disparate thresholds of these inputs may be brought into closer register, resulting in a steepened rate intensity function. These observations may be germane to the neural genesis of the "recruitment" seen in the loudness judgments of normal listeners for masked tones.