Functional organization of sound direction and sound pressure level in primary auditory cortex of the cat

1994 ◽  
Vol 72 (5) ◽  
pp. 2383-2405 ◽  
Author(s):  
J. C. Clarey ◽  
P. Barone ◽  
T. J. Imig
Keyword(s):  
Auditory Cortex ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Functional Organization ◽  
Primary Auditory Cortex ◽  
Pressure Level ◽  
Cortical Surface ◽  
Data Set ◽  
Function Type ◽  
Level Function

1. The functional organization of neuronal tuning to the azimuthal location and sound pressure level (SPL) of noise bursts was studied in high-frequency primary auditory cortex (AI) of barbiturate-anesthetized cats. Three data collection strategies were used to map neural responses: 1) electrode penetrations oriented normal to the cortical surface provided information on the radial organization of neurons' responses; 2) neurons' responses were examined at a few points in the middle cortical layers in multiple normal penetrations across AI to produce fine-grain maps of azimuth and level selectivity; and 3) electrode penetrations oriented tangential to the cortical surface provided information on neurons' responses along the isofrequency dimension. 2. An azimuth-level data set was obtained for each single- or multiple- (multi-) unit recording; this consisted of responses to noise bursts at five SPLs (0–80 dB in 20-dB steps) from seven azimuthal locations in the frontal hemifield (-90 to +90 degrees in 30 degrees steps; 0 degree elevation). An azimuth function was derived from these data by averaging response magnitude over all SPLs at each azimuth tested. A preferred azimuth range (PAR; range of azimuths over which the response was > or = 75% of maximum) was calculated from the azimuth function and provided a level-independent measure of azimuth selectivity. Each PAR was assigned to one of four azimuth preference categories (contralateral-, midline-, ipsilateral-preferring, or broad/multipeaked) according to its location and extent. A level function obtained from the data set (responsiveness averaged over all azimuths) was classified as monotonic if it showed a decrease of < or = 25% (relative to maximum) at the highest SPL tested (usually 80 dB), and nonmonotonic if it showed a decrease of > 25%. The percentage reduction in responsiveness, relative to maximum, at the highest level tested (termed nonmonotonic strength) and the preferred level range (PLR; range of SPLs over which responsiveness was > or = 75% of maximum) of each response was also determined. 3. Normal penetrations typically showed a predominance of one azimuth preference category and/or level function type. The majority of penetrations (26/36: 72.2%) showed statistically significant azimuth preference homogeneity, and approximately one-half (17/36: 47.2%) showed significant level function type homogeneity. Over one-third (13/36) showed significant homogeneity for both azimuth preference and level function type. 4. Mapping experiments (n = 4) sampled the azimuth and level response functions at two or more depths in closely spaced normal penetrations that covered several square millimeters of AI.(ABSTRACT TRUNCATED AT 400 WORDS)

Binaural processing of sound pressure level in cat primary auditory cortex: evidence for a representation based on absolute levels rather than interaural level differences

1993 ◽  
Vol 69 (2) ◽  
pp. 449-461 ◽  
Author(s):  
M. N. Semple ◽  
L. M. Kitzes
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Primary Auditory Cortex ◽  
Response Strength ◽  
Simple Relation ◽  
Pressure Level ◽  
Interaural Level Difference ◽  
Single Neurons

1. Single-neuron responses were recorded in high-frequency regions of primary auditory cortex (AI) of anesthetized cats. Best-frequency tone pips were presented to each ear independently via sealed stimulus delivery systems, and the sound pressure level (SPL) at each ear was independently manipulated. Each neuron was studied with many dichotic combinations of SPL, chosen to incorporate a broad range of the two synthetic interaural level variables, interaural level difference (ILD) and average binaural level (ABL). This paper illustrates the common forms of binaural SPL selectivity observed in a sample of 204 single neurons located in AI. 2. Most neurons (> 90%) were jointly influenced by ILD and ABL. A small proportion of bilaterally excitable (EE) neurons responded to ABL rather independently of ILD. Only one neuron was determined to respond to ILD independently of ABL. 3. Nonmonotonic selectivity for one or both of the binaural level cues was evident in > 60% of our sample. Within the most effective range of ILD values, response strength was usually related nonmonotonically to related both to ILD and ABL. We have described units exhibiting this kind of dual nonmonotonic selectivity for the two binaural variables as being influenced by a Two-Way Intensity Network (TWIN). 4. Each of the response forms identified in an earlier study of the gerbil inferior colliculus were found in this study of cat auditory cortex. However the classes were evident in markedly different proportions. In particular, TWIN responses alone accounted for 36.2% of the sample, nearly four times the proportion found in the inferior colliculus in a previous study. 5. Units with similar binaural responses do not necessarily have similar monaural properties. For example, the typically nonmonotonic relation between response strength and ABL was often observed in the absence of a monaurally demonstrable nonmonotonicity. There is no simple relation between a neuron's classification according to the sign of monaural influence and its response to ILD and ABL. In particular, EE neurons exhibited remarkably diverse binaural properties. 6. Since responses of nearly all AI neurons are influenced jointly by ABL and ILD, we contend that single neurons in primary auditory cortex are not specifically tuned to either cue. ILD and ABL are mathematical expressions relating the SPLs at the two ears to each other (as the difference and average, respectively) and any such combination is expressed most simply as a particular combination of SPL at each ear.(ABSTRACT TRUNCATED AT 400 WORDS)

Single-unit selectivity to azimuthal direction and sound pressure level of noise bursts in cat high-frequency primary auditory cortex

1990 ◽  
Vol 63 (6) ◽  
pp. 1448-1466 ◽  
Author(s):  
T. J. Imig ◽  
W. A. Irons ◽  
F. R. Samson
Keyword(s):  
Auditory Cortex ◽  
Sound Pressure Level ◽  
Sound Source ◽  
Single Unit ◽  
Sound Pressure ◽  
Free Field ◽  
Sound Field ◽  
Primary Auditory Cortex ◽  
Pressure Level ◽  
Broadband Noise

1. The azimuth and sound pressure level (SPL) selectivities of single-unit responses recorded in primary auditory cortex of barbiturate-anesthetized cats were studied by the use of broadband noise bursts delivered in the free field from a moveable loud-speaker. The experiments were carried out with cats located inside a quasianechoic sound-isolation chamber. We studied 71 units with relatively stable response properties. All units were located in the frequency representation between 5.8 and 31 kHz. The data obtained for each unit were displayed as an azimuth-level response area, a contour plot that displays the distribution of response magnitude as a joint function of SPL and azimuth at 0 degrees elevation. From these, azimuth and level functions were obtained to derive descriptors of azimuth and level selectivity. 2. Sensitivity to sound-source azimuth was assessed from the modulation of the average azimuth function (average of azimuth functions obtained to each SPL of noise that was presented) for each unit. The sample was arbitrarily divided into a high-directionality (HD) group (66%) whose average azimuth functions had modulation values of greater than or equal to 75% and a low-directionality (LD) group (34%). The distinction between HD and LD groups was made so that we could analyze the characteristics of units likely to be involved in the representation of sound-source azimuth. 3. There is an overrepresentation of the contralateral sound field and the midline in the sample of HD units. The preferred sector for each unit was defined as the range of azimuths within the frontal sound field throughout which unit response was greater than or equal to 75% of maximum. Each unit was classified as either midline preferring (17%, the midpoint of the preferred sector, i.e., best azimuth, was located within 5 degrees of the midline), contralateral preferring (60%), or ipsilateral preferring (23%). The ratio of contralateral- to ipsilateral-preferring units was 2.5:1. A higher proportion of units had best azimuths located in the 10 degrees sector centered on the midline than in any other 10 degrees sector of the frontal sound field. 4. In one animal, recordings were obtained at seven closely spaced sites in layer IV from single- and multiunit responses, which were narrowly tuned to both azimuth and SPL. The units located along a 1-mm length of an isofrequency strip were tuned to similar frequencies and SPLs but had five distinctly different directional preferences distributed throughout the entire frontal sound field.(ABSTRACT TRUNCATED AT 400 WORDS)

Focal selectivity for binaural sound pressure level in cat primary auditory cortex: two-way intensity network tuning

1993 ◽  
Vol 69 (2) ◽  
pp. 462-473 ◽  
Author(s):  
M. N. Semple ◽  
L. M. Kitzes
Keyword(s):  
Auditory Cortex ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Preceding Paper ◽  
Primary Auditory Cortex ◽  
Pressure Level ◽  
Response Magnitude ◽  
Interaural Level Difference ◽  
Single Class ◽  
Effective Combination

1. The influence of sound pressure level (SPL) at the two ears was studied in single-neuron responses recorded in high-frequency regions of primary auditory cortex (AI) of anesthetized cats. For each unit, many binaural combinations of SPL were tested by using best-frequency tone pips presented to each ear independently via sealed stimulus delivery systems. In the preceding paper, we illustrated the different forms of response observed in our sample of units. Here we explore in more detail the mechanisms underlying the properties of the largest single class of binaural response, characterized by joint nonmonotonic tuning to the SPLs at the two ears. We have described such units as being influenced by a Two-Way Intensity Network (TWIN). 2. Under binaural conditions, 62% of our sample of well documented neurons (81/130) exhibited a nonmonotonic relation between response magnitude and the SPL at one or the other ear. Of these units, 47 displayed clear bilateral nonmonotonicity (TWIN tuning), 17 units displayed only unilateral nonmonotonicity, and an additional 17 units showed intermediate (or transitional) characteristics between unilateral and bilateral nonmonotonicity. These characteristics can also be described in terms of average binaural level (ABL) and interaural level difference (ILD). Thus there is commonly a nonmonotonic relation between response magnitude and ABL and sometimes a TWIN tuning to ABL and ILD. The distribution of best frequencies for TWIN neurons is broad. 3. Under monaural conditions, TWIN neurons exhibit diverse properties. Some are responsive only under binaural conditions [i.e., predominantly binaural (PB)]. Some monaurally responsive TWINs are contralaterally excitable and ipsilaterally unresponsive (EO), some are ipsilaterally excitable and contralaterally unresponsive (OE), and a few are bilaterally excitable (EE). Monaural rate/level functions are monotonic for some of these neurons and nonmonotonic for others. Neurons of the PB class have previously been found to have nonmonotonic selectivity for ILDs near zero. In this study we have found that virtually all PB neurons are also nonmonotonically selective for ABL with different PB neurons having different best ABLs. 4. For TWIN neurons that respond monaurally, it is possible to demonstrate a mixed binaural influence. The optimal stimulus (or best binaural combination) for a TWIN neuron is associated with binaural facilitation. Flanking the most effective combination of ABL and ILD are less effective combinations that generate lower response magnitudes, either through threshold effects (at low SPLs) or through binaural suppression (at higher SPLs).(ABSTRACT TRUNCATED AT 400 WORDS)

Tonotopic and functional organization in the auditory cortex of the big brown bat, Eptesicus fuscus

1993 ◽  
Vol 70 (5) ◽  
pp. 1988-2009 ◽  
Author(s):  
S. P. Dear ◽  
J. Fritz ◽  
T. Haresign ◽  
M. Ferragamo ◽  
J. A. Simmons
Keyword(s):  
Auditory Cortex ◽  
Surface Area ◽  
Cortical Neurons ◽  
Functional Organization ◽  
Primary Auditory Cortex ◽  
Target Range ◽  
Cortical Surface ◽  
Behavioral Experiments ◽  
Cortical Surface Area ◽  
Harmonic Ratio

1. In Eptesicus the auditory cortex, as defined by electrical activity recorded from microelectrodes in response to tone bursts, FM sweeps, and combinations of FM sweeps, encompasses an average cortical surface area of 5.7 mm2. This area is large with respect to the total cortical surface area and reflects the importance of auditory processing to this species of bat. 2. The predominant pattern of organization in response to tone bursts observed in each cortex is tonotopic, with three discernible divisions revealed by our data. However, although cortical best-frequency (BF) maps from most of the individual bats are similar, no two maps are identical. The largest division contains an average of 84% of the auditory cortical surface area, with BF tonotopically mapped from high to low along the anteroposterior axis and is part of the primary auditory cortex. The medium division encompasses an average of 13% of the auditory cortical surface area, with highly variable BF organization across bats. The third region is the smallest, with an average of only 3% of auditory cortical surface area and is located at the anterolateral edge of the cortex. This region is marked by a reversal of the tonotopic axis and a restriction in the range of BFs as compared with the larger, tonotopically organized division. 3. A population of cortical neurons was found (n = 39) in which each neuron exhibited two BF threshold minima (BF1 and BF2) in response to tone bursts. These neurons thus have multipeaked frequency threshold tuning curves. In Eptesicus the majority of multipeaked frequency-tuned neurons (n = 27) have threshold minima at frequencies that correspond to a harmonic ratio of three-to-one. In contrast, the majority of multipeaked neurons in cats have threshold minima at frequencies in a ratio of three-to-two. A three-to-one harmonic ratio corresponds to the "spectral notches" produced by interference between overlapping echoes from multiple reflective surfaces in complex sonar targets. Behavioral experiments have demonstrated the ability of Eptesicus to use spectral interference notches for perceiving target shape, and this subpopulation of multipeaked frequency-tuned neurons may be involved in coding of spectral notches. 4. The auditory cortex contains delay-tuned neurons that encode target range (n = 99). Most delay-tuned neurons respond poorly to tones or individual FM sweeps and require combinations of FM sweeps. They are combination sensitive and delay tuned.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Field Study of the Interior Noise and Vibration of a Metro Vehicle Running on a Viaduct: A Case Study in Guangzhou

2020 ◽  
Vol 17 (8) ◽  
pp. 2807
Author(s):  
Lei Yan ◽  
Zhou Chen ◽  
Yunfeng Zou ◽  
Xuhui He ◽  
Chenzhi Cai ◽  
...  
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Interior Noise ◽  
Vehicle Body ◽  
Frequency Noise ◽  
Data Set ◽  
Noise And Vibration ◽  
Acceleration Level ◽  
Frequency Peak

The interior noise and vibration of metro vehicles have been the subject of increasing concern in recent years with the development of the urban metro systems. However, there still is a lack of experimental studies regarding the interior noise and vibration of metro vehicles. Therefore, overnight field experiments of the interior noise and vibration of a standard B-type metro train running on a viaduct were conducted on metro line 14 of Guangzhou (China). Both the A-weighted sound pressure level and linear sound pressure level were used to evaluate the interior noise signals in order to revel the underestimation of the low-frequency noise components. The results show that the interior noise concentrates in the low-to-middle frequency range. Increasing train speeds have significant effects on the sound pressure level inside the vehicle. However, two obvious frequency ranges (125–250 Hz and 400–1000 Hz) with respective corresponding center frequencies (160 Hz and 800 Hz) of the interior noise are nearly independent of train speed. The spectrum analysis of the vehicle body vibration shows that the frequency peak of the floor corresponds to the first frequency peak of the interior noise spectrum. There are two frequency peaks around 40 Hz and 160 Hz of the sidewall’s acceleration level. The frequency peaks of the acceleration level are also independent of the train speeds. It hopes that the field measurements in this paper can provide a data set for researchers for further investigations and can contribute to the countermeasures for reducing interior noise and vibration of a metro vehicle.

Responses of single neurons in posterior field of cat auditory cortex to tonal stimulation

1984 ◽  
Vol 51 (1) ◽  
pp. 147-163 ◽  
Author(s):  
D. P. Phillips ◽  
S. S. Orman
Keyword(s):  
Auditory Cortex ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Frequency Tuning ◽  
Tuning Curve ◽  
Pressure Level ◽  
Spike Count ◽  
Single Neurons ◽  
High Stimulus ◽  
Posterior Field

In the auditory cortex of barbiturate-anesthetized cats, the posterior auditory field (field P) was identified by its tonotopic organization, and single neurons in that field were studied quantitatively for their sensitivity to the frequency and intensity of tonal stimuli presented via calibrated, sealed stimulating systems. Field P neurons had narrow, V-shaped, threshold frequency tuning curves. At suprathreshold levels, spike counts were generally greatest at frequencies at or close to the neuron's threshold best frequency (BF). Eighty-six percent of posterior-field neurons displayed spike counts that were a nonmonotonic function of the intensity of a BF tone. Of these, over 90% showed at least a 50% reduction in spike count at high stimulus levels, and almost 20% of nonmonotonic cells ceased responding entirely at high stimulus intensities. The nonmonotonic shape of spike count-versus-intensity profiles was typically preserved across the range of frequencies to which any given neuron was responsive. For some neurons, this had the consequence of generating a completely circumscribed frequency-intensity response area. That is, these neurons responded to a tonal stimulus only if the stimulus was within a restricted range of both frequency and intensity. These response areas showed internal organizations that appeared to reflect one or both of two processes. For some neurons, the optimal sound pressure level for spike counts varied with tone frequency, roughly paralleling the threshold tuning curve. For other neurons, the optimal sound pressure level tended to be constant across frequency despite threshold variations of up to 20 dB. The minimum response latencies of posterior-field neurons were generally in the range of 20-50 ms, while cells in the primary auditory cortex (AI) in the same animals generally had minimum latent periods of less than 20 ms. Comparison of these data with those previously presented for neurons in two other cortical auditory fields suggests that the cat's auditory cortex might show an interfield segregation of neurons according to their coding properties.

Narrow sound pressure level tuning in the auditory cortex of the bats Molossus molossus and Macrotus waterhousii

2014 ◽  
Vol 309 ◽  
pp. 36-43 ◽  
Author(s):  
Silvio Macías ◽  
Julio C. Hechavarría ◽  
Ariadna Cobo ◽  
Emanuel C. Mora
Keyword(s):  
Auditory Cortex ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Molossus Molossus

Contributions of Voice and Nonverbal Communication to Perceived Masculinity–Femininity for Cisgender and Transgender Communicators

2020 ◽  
Vol 63 (4) ◽  
pp. 931-947
Author(s):  
Teresa L. D. Hardy ◽  
Carol A. Boliek ◽  
Daniel Aalto ◽  
Justin Lewicke ◽  
Kristopher Wells ◽  
...  
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Vocal Tract ◽  
Presentation Mode ◽  
Pressure Level ◽  
Presentation Modes ◽  
Audiovisual Stimuli ◽  
Vocal Tract Resonance ◽  
Point Light

Purpose The purpose of this study was twofold: (a) to identify a set of communication-based predictors (including both acoustic and gestural variables) of masculinity–femininity ratings and (b) to explore differences in ratings between audio and audiovisual presentation modes for transgender and cisgender communicators. Method The voices and gestures of a group of cisgender men and women ( n = 10 of each) and transgender women ( n = 20) communicators were recorded while they recounted the story of a cartoon using acoustic and motion capture recording systems. A total of 17 acoustic and gestural variables were measured from these recordings. A group of observers ( n = 20) rated each communicator's masculinity–femininity based on 30- to 45-s samples of the cartoon description presented in three modes: audio, visual, and audio visual. Visual and audiovisual stimuli contained point light displays standardized for size. Ratings were made using a direct magnitude estimation scale without modulus. Communication-based predictors of masculinity–femininity ratings were identified using multiple regression, and analysis of variance was used to determine the effect of presentation mode on perceptual ratings. Results Fundamental frequency, average vowel formant, and sound pressure level were identified as significant predictors of masculinity–femininity ratings for these communicators. Communicators were rated significantly more feminine in the audio than the audiovisual mode and unreliably in the visual-only mode. Conclusions Both study purposes were met. Results support continued emphasis on fundamental frequency and vocal tract resonance in voice and communication modification training with transgender individuals and provide evidence for the potential benefit of modifying sound pressure level, especially when a masculine presentation is desired.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

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