Loudness Magnitude Research Articles

Acoustics of the banjo: measurements and sound synthesis

Measurements of vibrational response of an American 5-string banjo and of the sounds of played notes on the instrument are presented, and contrasted with corresponding results for a steel-string guitar. A synthesis model, fine-tuned using information from the measurements, has been used to investigate what acoustical features are necessary to produce recognisable banjo-like sound, and to explore the perceptual salience of a wide range of design modifications. Recognisable banjo sound seems to depend on the pattern of decay rates of “string modes”, the loudness magnitude and profile, and a transient contribution to each played note from the “body modes”. A formant-like feature, peaking around 500–800 Hz on the banjo tested, is found to play a key role. At higher frequencies the dynamic behaviour of the bridge produces additional formant-like features, reminiscent of the “bridge hill” of the violin, and these also produce clear perceptual effects.

Developing Clinically Relevant Scales of Breathy and Rough Voice Quality

The most common measurement tools used in the perceptual evaluation of voice quality yield ordinal data and thus do not support the establishment of mathematical relationships among different measurement values. This makes their interpretation challenging. Among the many desirable features of any psychophysical measurement tool is the ability to quantify the difference between two or more measurements and the ability to interpret the measurements in a manner that is related to the experience of the observer. The former allows one to compare among measurements using simple mathematics, while the latter allows that comparison to be interpreted in constructive ways. In this paper we describe the development of standard measurement scales for two dimensions of voice quality, following an approach that has been applied successfully to the perception of loudness. The scales follow step-by-step procedures used to develop the sone scale of loudness, which ties physical units to the perceptual estimates of loudness magnitude. Goals of the current work include development of analogous scales for the perception of breathy and rough voice qualities. First, the relationship between perceived voice quality and physical units were established using single-variable matching tasks. Second, the relationship between a change in physical units from the single-variable matching tasks and perceived voice quality magnitude were established using magnitude estimation tasks. Third, single reference points were identified on breathy and rough continuums. Finally, all points on the newly established voice quality continuums were rescaled relative to these arbitrary reference points. The proposed breathiness and roughness scales result in ratio-level data with standard measurement units that support quantitative comparisons of perceptual judgments. Such judgments can be used, for example, to compare magnitude of change pre- and post-treatment.

Analysis of frequency dependence on short-term annoyance of conventional railway noise using sound quality metrics in a laboratory context

Since the early 20th century, many studies have been conducted about the noise characteristics of trains, particularly in regards to annoyance. However, none of the studies considered the frequency dependence of short-term annoyance of railway noise. Moreover, none of the studies was performed to observe the change of the annoyance using sound quality metrics when the frequency component of railway noise was modified. Thus, in the current study, after experimentally confirming the validity of using sound quality metrics as assessment units, the frequency dependence of short-term annoyance was investigated that included sound quality metrics based on frequency-modified ‘conventional’ railway noise. Three experiments were conducted on the study. In the first experiment, 50 participants determined the words most suitable to represent the quantity of railway noise, and the metrics that were expected to be most relevant to railway noise were identified. Using the results from the first experiment, 50 participants estimated the magnitude of subjective loudness, subjective sharpness, and the annoyance of the railway noise to verify the reasonability of using sound quality metrics as the assessment units of estimating the frequency dependence. From the results of the second experiment, it was determined that the subjective factors and the calculated factors had clear linear relationships, and it was identified that sound quality metrics can be used to determine the frequency dependence of short-term annoyance of the railway noise. In the third experiment, 50 participants estimated the upper and lower limits of hearing perception of subjective loudness of the railway noise to identify the frequency sensitivity of participants to the railway noise. Finally, case studies were conducted on short-term annoyance model using multiple regression method, which confirmed the frequency dependence of the annoyance of the railway noise.

The impact of perilaryngeal vibration on the self-perception of loudness and the Lombard effect

The role of somatosensory feedback in speech and the perception of loudness was assessed in adults without speech or hearing disorders. Participants completed two tasks: loudness magnitude estimation of a short vowel and oral reading of a standard passage. Both tasks were carried out in each of three conditions: no-masking, auditory masking alone, and mixed auditory masking plus vibration of the perilaryngeal area. A Lombard effect was elicited in both masking conditions: speakers unconsciously increased vocal intensity. Perilaryngeal vibration further increased vocal intensity above what was observed for auditory masking alone. Both masking conditions affected fundamental frequency and the first formant frequency as well, but only vibration was associated with a significant change in the second formant frequency. An additional analysis of pure-tone thresholds found no difference in auditory thresholds between masking conditions. Taken together, these findings indicate that perilaryngeal vibration effectively masked somatosensory feedback, resulting in an enhanced Lombard effect (increased vocal intensity) that did not alter speakers' self-perception of loudness. This implies that the Lombard effect results from a general sensorimotor process, rather than from a specific audio-vocal mechanism, and that the conscious self-monitoring of speech intensity is not directly based on either auditory or somatosensory feedback.

Right-Ear Advantage for Speech-in-Noise Recognition in Patients with Nonlateralized Tinnitus and Normal Hearing Sensitivity.

Despite having normal hearing sensitivity, patients with chronic tinnitus may experience more difficulty recognizing speech in adverse listening conditions as compared to controls. However, the association between the characteristics of tinnitus (severity and loudness) and speech recognition remains unclear. In this study, the Quick Speech-in-Noise test (QuickSIN) was conducted monaurally on 14 patients with bilateral tinnitus and 14 age- and hearing-matched adults to determine the relation between tinnitus characteristics and speech understanding. Further, Tinnitus Handicap Inventory (THI), tinnitus loudness magnitude estimation, and loudness matching were obtained to better characterize the perceptual and psychological aspects of tinnitus. The patients reported low THI scores, with most participants in the slight handicap category. Significant between-group differences in speech-in-noise performance were only found at the 5-dB signal-to-noise ratio (SNR) condition. The tinnitus group performed significantly worse in the left ear than in the right ear, even though bilateral tinnitus percept and symmetrical thresholds were reported in all patients. This between-ear difference is likely influenced by a right-ear advantage for speech sounds, as factors related to testing order and fatigue were ruled out. Additionally, significant correlations found between SNR loss in the left ear and tinnitus loudness matching suggest that perceptual factors related to tinnitus had an effect on speech-in-noise performance, pointing to a possible interaction between peripheral and cognitive factors in chronic tinnitus. Further studies, that take into account both hearing and cognitive abilities of patients, are needed to better parse out the effect of tinnitus in the absence of hearing impairment.

Pure-Tone-Spondee Threshold Relationships in Functional Hearing Loss: A Test of Loudness Contribution.

The purpose of this article is to examine explanations for pure-tone average-spondee threshold differences in functional hearing loss. Loudness magnitude estimation functions were obtained from 24 participants for pure tones (0.5 and 1.0 kHz), vowels, spondees, and speech-shaped noise as a function of level (20-90 dB SPL). Participants listened monaurally through earphones. Loudness predictions were obtained for the same stimuli by using a computational, dynamic loudness model. When evaluated at the same SPL, speech-shaped noise was judged louder than vowels/spondees, which were judged louder than tones. Equal-loudness levels were inferred from fitted loudness functions for the group. For the clinical application, the 2.1-dB difference between spondees and tones at equal loudness became a 12.1-dB difference when the stimuli were converted from SPL to HL. Nearly all of the pure-tone average-spondee threshold differences in functional hearing loss are attributable to references for calibration for 0 dB HL for tones and speech, which are based on detection and recognition, respectively. The recognition threshold for spondees is roughly 9 dB higher than the speech detection threshold; persons feigning a loss, who base loss magnitude on loudness, do not consider this difference. Furthermore, the dynamic loudness model was more accurate than the static model.

Some factors affecting loudness measurement and prediction

The current ANSI standard (ANSI S3.4, 2007) estimates the loudness of sustained sound, but many naturally occurring sounds have time-varying levels. Glasberg and Moore (2002) published a model for the prediction of time-varying sounds and this aspect should be considered as part of a revision to the ANSI standard. To assess the predictions of the dynamic model, loudness magnitude estimation functions were obtained for 24 listeners using pure tones (0.5 and 1.0 kHz), vowels, spondees, and speech-shaped noise (SSN) presented at levels from 40 to 90 dB SPL. Inferred equal-loudness levels from the fitted loudness functions were compared to the model predictions. The loudness model was qualitatively consistent with the behavioral data. The model predicted SSN to be louder than vowels and spondees which would be louder than tones; however, the model over-predicted the loudness differences. Possible explanations for the over-prediction include biases in loudness judgments, cognitive factors regarding learned expectations for loudness, assumptions regarding the free-field-to-headphone transfer function, and the model’s over-prediction of spectral, loudness summation, a result found recently (Schlittenlacher et al., 2014) for the ANSI standard and DIN 45631.

Towards standard scales for dysphonic voice quality: Magnitude estimation of reference stimuli

This work represents a critical step in developing standard measurement scales for the dysphonic voice qualities of breathiness and roughness. Methods such as Likert ratings, visual analog scales and magnitude estimation result in arbitrary units, limiting their clinical usefulness. A single-variable matching task can quantifying voice quality in terms of physical units but is too time consuming for clinical use. None of these methods result in information that has a direct or intuitive relationship with the underlying percept. A proven approach for the perception of loudness is the Sone scale which ties physical units to the perceptual estimates of loudness magnitude. As a first step in developing such a scale for breathiness and roughness, here we establish the relationship between the change in perceived VQ magnitude and the change in physical units along the continuum of each VQ dimension. A group of 25 listeners engaged in a magnitude estimation task to determine perceived magnitude associated with the comparison stimuli used in our single-variable matching tasks. This relationship is analogous to mapping intensity in dB to perceived loudness in Phons and is a critical step in developing a Sone-like scale for breathiness and roughness.

The listener's temperament and perceived tempo and loudness of music

The relationship between the listener's temperament and perceived magnitude of tempo and loudness of music was studied using the techniques of magnitude production, magnitude estimation scaling and cross‐modal matching. Four piano pieces were presented at several levels of tempo and loudness. In Study 1, participants adjusted tempo and loudness of music to their subjective level of comfort. In Study 2, participants estimated these parameters on a numerical scale and matched the length of a line segment to the estimates of these musical features. The results showed significant correlations of selected aspects of perceived tempo with perseveration and endurance as well as of selected aspects of perceived loudness with endurance and emotional reactivity. Perceived tempo and loudness, as measured by magnitude production and cross‐modal matching tasks, do not seem to systematically correlate with the six formal characteristics of behaviour distinguished in the most recent version of the Regulative Theory of Temperament (RTT). Additionally, there is some evidence that they are selectively associated with reactivity and activity, the dimensions of a previous version of the RTT. The study extends the methodology of research on music preferences and the stimulatory value of music. Copyright © 2009 John Wiley & Sons, Ltd.

Application of loudness models to sound processing for cochlear implants.

A new paradigm for processing sound signals for multiple-electrode cochlear implants is introduced, and results are presented from an initial psychophysical evaluation of its effect on the perceived loudness of complex sounds. A real-time processing scheme based on this paradigm, called SpeL, has been developed primarily to improve control of loudness for implant users. SpeL differs from previous schemes in several ways. Most importantly, it incorporates a published numerical model which predicts the loudness perceived by implant users for complex patterns of pulsatile electric stimulation as a function of the pulses' physical parameters. This model is controlled by the output of a corresponding model that estimates the loudness perceived by normally hearing listeners for complex sounds. The latter model produces an estimate of the specific loudness arising from an acoustic signal. In SpeL, the specific loudness function, which describes the contribution to total loudness of each of a number of frequency bands (or cochlear positions), is converted to a pattern of electric stimulation on an appropriate set of electrodes. By application of the loudness model for electric stimulation, this pattern is designed to produce a specific loudness function for the implant user which approximates that produced by the normal-hearing model for the same input signal. The results of loudness magnitude estimation experiments with five users of the SpeL scheme confirmed that the psychophysical functions relating overall loudness perceived to input sound level for five complex acoustic signals were, on average, very similar to those for normal hearing.

Loudness adaptation in listeners with high frequency impairment

High-frequency impairment was found to have a significant effect on ipsilateral loudness magnitude adaptation in complex interactions [Korman etal., J. Acoust. Soc. Am. Suppl. 1 81, S76 (1987)]. The present study used simple comparisons of 12 listeners with high-frequency hearing loss, age matched with 12 having no loss. All were tested at 1 kHz for adaptation at 40 and 60 dB HTL. [See Weiler etal., Brit. J. Audiol. 15, 204–205 (1981).] The hearing loss group showed significantly more adaptation at 40 dB than at 60, while normals showed the same amount. Based on the two studies, it appears that high-frequency hearing loss does have some effect on the loudness function at 1 kHz where hearing appears to be normal.

Overall loudness of tone-noise complexes: Measured and calculated

Loudness measured for single-tone-noise complexes [R. P. Hellman, J. Acoust. Soc. Am. 72, 62–73 (1982)] is compared to loudness calculated in accordance with a loudness-calculation program based on ISO 532 B [E. Zwicker, H. Fast, and C. Dallmayr, Acustica 55, 63–67 (1984)]. Data are given for single tones centered within the spectrum of broadband-flat, low-pass, and high-pass noises. The measured and calculated loudness functions exhibit a similar pattern of loudness growth. Both measured and calculated loudness of the tone-noise complexes are nonmonotonic functions of the overall SPL of the complex. Thus two tone-noise combinations at nearly the same overall SPL can produce markedly different loudness values. These results hold over a 30-dB range from about 73–103 dB. The results also show that the magnitude of loudness depends on the spectral shape of the noise and the frequency of the added tone. The close agreement between the measured and calculated loudness-growth patterns means that basic psychoacoustical principles governing loudness and masking can account for the observed effects. [Supported by the Rehabilitation Research and Development Service of the VA and by the Deutsche Forschungsmeinschaft.]

Effect of sloping high‐frequency cochlear losses on loudness functions at lower frequencies

The relation between loudness at low and middle frequencies and auditory thresholds at high frequencies was determined in a hearing‐impaired population with sloping high‐frequency cochlear losses. Nine people, all with steep symmetrical bilateral losses, participated in the study. Loudness was measured at two frequencies in the normal‐hearing region by magnitude estimation and production. Despite a marked increase in thresholds at frequencies just above the upper test frequency, both the dynamic range measured for loudness and the tone's rate of loudness growth were essentially the same at the two test frequencies. Moreover, the loudness functions were the same as the monaural loudness function measured at 1000 Hz in normal hearing. Consistent with the findings of other studies, the results indicate that the magnitude of loudness does not depend on the high‐frequency excitation pattern evoked by the tone in the ear. [Supported by the Rehabilitation Research and Development Service of the VA.]

Intensity jnd's for equally loud tones in quiet and noise backgrounds

Recent studies of the relation between loudness and intensity jnd's suggest that the size of the jnd corresponds to loudness magnitude rather than to the slope of the loudness function. Specifically, Zwislocki and Jordan [J. Acoust. Soc. Am. Suppl. 1 77, S64 (1985)] conclude that the intensity jnd's for a pure tone are equal in recruiting and normal ears when the loudnesses of the tones are equal. Similarly, Hellman et al. [J. Acoust. Soc. Am. Suppl. 1 77, S64 (1985)] conclude that when a pure tone in narrow‐band noise is judged to be equally loud to a tone in wideband noise, the jnd's for those tones are the same. We show exception to these studies. Loudness matches and intensity jnd's for a 1000‐Hz pure tone in quiet and in a 40‐dB spectrum level broadband noise were obtained for four normal‐hearing subjects. The data indicate that equally loud tones yield equal jnd's only at intensities near threshold and at high intensities where equal loudness corresponds to equal SPL. At other intensities, the jnd is larger in noise than in quiet. [Supported by NIH NS12125, NS07889, and by a training grant, NICHHD T32 HD‐07151, awarded to CMR by the Center for Research in Human Learning.]

On the relations of intensity jnd’s to loudness and neural noise

It is shown experimentally that, in contradiction of the fundamental concept of Fechner's law, the intensity jnd for auditory sinusoidal signals follows loudness, rather than its derivative with respect to sound intensity. The evidence is obtained by comparing the jnd's of a population with normal hearing to those of a population with hearing loss accompanied by loudness recruitment. Although the recruitment increases the slope of the loudness function, the jnd's of both populations were found to be practically equal when the loudness were equal. The phenomenon is accounted for mathematically by assuming that psychophysically relevant neural noise depends not only on the magnitude of loudness, but also on its derivative with respect to sound intensity. A related derivation accounts for the near miss to Weber's law.

Acoustic-reflex growth for multitone complexes.

The effects of activator spectral density on the growth characteristics of the acoustic reflex were evaluated in normal-hearing subjects. Reflex-growth dynamics were evaluated for computer-synthesized activators composed of 2 to 50 components and bandwidths wider and more narrow than the reported critical band for loudness summation. Although acoustic-reflex characteristics varied with activator bandwidth, there were no significant differences in reflex-growth patterns as a function of activator density (number of components). The findings suggest that, like loudness summation, growth or magnitude characteristics of the acoustic reflex are unaffected by the spectral density of the signal.

SDLB adaptation and an approximation of Steven's power law

Initial curve fitting efforts having yielded similar results, data from four studies [E. Jerger, J. Acoust. Soc. Am. 29, 357–363 (1957); T. Palva and J. Karja, J. Acoust. Soc. Am. 45, 1018–1021 (1969); E. M. Weiler, M. Loeb, and E. A. Alluisi, J. Acoust. Soc. Am. 51, 638–643 (1972); and E. M. Weiler and J. D. Hood, Audiology 16, 499–506 (1977)] were combined to encompass intensities from 20 to 80 dB SL at 1 kHz. All studies used the classic method of simultaneous dichotic loudness balances (SDLB} as described by Hood [Acta. Oto‐Laryngol. Suppl. 92 (1950)] and Small [Modern Developments in Audiology, edited by J. Jerger (Academic, New York, 1963)]. A regression line was fit to the log values of stimulus intensity and log adaptation (dB). Converting to the form of Steven's power law, the resulting constant K by this approach was 0.9449 and the exponent of intensity N was 0.73953. For loudness magnitudes, N has often been reported as about 0.60.

Masked loudness functions and their relation to intensity discrimination

One way to assess the relation between intensity discrimination and the slope of the loudness function is to measure the jnd for a sound that falls on two distinctly different loudness functions. Two such functions were generated by presenting a 1000‐Hz tone in narrow‐band noise (NBN, 925–1080 Hz) at 70 dB SPL and in wideband noise (WBN, 75–9600 Hz) at 80 dB SPL. Over a range from near threshold to about 75 dB SPL, the tone's loudness function is much steeper in the NBN than in the WBN. At 72 dB SPL, where the two loudness curves cross, we measured the tone's jnd in each noise by a two‐interval forced‐choice procedure. Despite the differences in slope (and in sensation level), the jnd was the same in both NBN and WBN. The value of ΔI/I was 0.22, which is close to that interpolated from Jesteadt, Wier, and Green [J. Acoust. Soc. Am. 61, 169–176 (1977)] for a 1000‐Hz tone at the same loudness in quiet as our 72‐dB tone in noise. These and other data suggest the possibility that the size of the jnd for intensity depends more on loudness magnitude than on the slope of the loudness function. [Supported by funds from the Medical Research Service of the VA to RH and by a grant (BMS 73‐06944) from NSF to RT.]

Group and individual relations between sensation magnitudes and their numerical estimates.

The study deals mainly with absolute magnitude estimation (AME) of the component loud-nesses and the total loudness of pairs of heterofrequency, sequential tone bursts. Two kinds of relations are derived from the obtained group and individual data on the assumption of loudness additivity and a two-stage scaling model. They refer to numerical loudness estimates versus derived loudness magnitudes and to the loudness magnitudes versus tone sensation levels. The relations are validated by means of indirect and direct loudness matches. In an auxiliary experiment, the same subjects performed AMEs of subjective line lengths. The resulting group and individual relations between the numerical estimates and the underlying physical line lengths were found to be nearly the same as those between the numerical loudness estimates and the derived loudness magnitudes. The mutual consistency among the several sets of empirical and derived data strongly supports the assumptions of loudness additivity and the two-stage model.

Power functions of loudness magnitude estimations and auditory brainstem evoked responses.

The correspondence between subjective and neural response to change in acoustic intensity was considered by deriving power functions from subjective loudness estimations and from the amplitude and latency of auditory brainstem evoked response components (BER). Thirty-six subjects provided loudness magnitude estimations of 2-sec trains of positive polarity click stimuli, 20/sec, at intensity levels ranging from 55 to 90 dB in 5-dB steps. The loudness power function yielded an exponent of .48. With longer trains of the same click stimuli, the exponents of BER latency measures ranged from -.14 for wave I to -.03 for later waves. The exponents of BER amplitude-intensity functions ranged from .40 to .19. Although these exponents tended to be larger than exponents previously reported, they were all lower than the exponent derived from the subjective loudness estimates, and a clear correspondence between the exponents of the loudness and BER component intensity functions was not found.