Showing papers in "Canadian Acoustics in 2009"

Prediction of flow-induced noise in transport vehicles: development and validation of a coupled structural - Acoustic analytical framework

Abstract: In this study, a complete analytical model framework able to accurately predict the flow-induced noise in the interior of a transport vehicle cabin is presented. The mathematical model framework presented represents a coupled structural-acoustic system, consisted by a plate subjected to a random excitation or to flow-induced noise, and an acoustic enclosure representing the transport vehicle cabin. The coupled analytical model is developed using the contribution of both structural and acoustic natural modes. It is shown that the analytical framework can be used for the prediction of flow-induced noise for different types of transport vehicles, by changing some of the parameters, as shown by the good agreement between the analytical results and several experimental studies. The results indicate that the analytical model is sensitive to the measurement location, with the change in position significantly affecting the predicted interior noise levels, as should be expected. Different sizes for the acoustic enclosure, as well as different types of panels were investigated. This study demonstrates the importance of including the acoustic receiving room (i.e., the vehicle cabin) contribution in the analytical formulation, in order to accurately predict the noise transmission and interior noise levels.

Deconstructing a musical delusion: Point-light representations capture salient properties of impact motions

Abstract: Although visual information affects auditory perception in a variety of tasks, audition is generally believed to be relatively immune from visual influence when judging tone duration. However, Schutz and Lipscomb (2007) report a musical illusion in which physical gestures influence the perceived duration of notes performed on the marimba. In order to better understand which aspects of these gestures are responsible for the illusion, we created a "schematic marimbist" consisting of either a four-point skeleton or a single moving dot. This schematic abstraction captured the essential properties of the gestures, replicating the effect under both conditions. Therefore, this illusion requires seeing only a sudden change in gesture direction - independent of the depiction of a struck object. As this finding means that it can be replicated with a minimum of visual information, it will be useful in facilitating future research aimed at uncovering the reason for this break with the widely accepted theory of 'optimal integration'.

I have never seen a sound

Abstract: R Murray Schafer, Indian River, Ontario, Canada shares his views about some significant aspects of sound He informs that sounds are verbs as compared sights, which are nouns and can be seen Sounding can be active and generative in nature and it is incomparable similar to other creations Visual metaphors and scaling systems have been developed to measure and analyze sounds These techniques and systems are unable to weigh a whisper, count the voices in a choir, or measure a child's laughter Sound is able to reach and travel to places where sight is unable to reach, as it reaches under the surface and other things R Murray Schafer states that sounds can be found in all places and objects, including silent objects and the environment Sounds have played a key role in the creation of music and are associated with different natural phenomenon

Cross-modal melodic contour similarity

Abstract: In two experiments participants rated the similarity of melodic contours presented as auditory (melodies) and visual (line drawings) stimuli. Longer melodies were assessed in Experiment 1 (M = 35 notes); shorter melodies were assessed in Experiment 2 (M = 17 notes). Ratings for matched auditory and visual contours exceeded ratings for mismatched contours, confirming cross-modal sensitivity to contour. The degree of overlap of the surface structure (the relative position of peaks and troughs), and the strength and timing of the cyclical information (the amplitude and phase spectra produced by a Fourier analysis) in the contours predicted cross-modal similarity ratings. Factors such as the order of stimulus presentation (auditory-visual or visual-auditory), melody length (long versus short), and musical experience also affected the perceived similarity of contours. Results validate the applicability of existing contour models to cross-modal contexts and reveal additional factors that contribute to cross-modal contour similarity.

Wlthtn-category variation in l2 english vowel learning

Abstract: A study was conducted to investigate whether second language (L2) learners had the ability to produce English vowels when they were presented in more familiar words and when learners had access to orthographic representations of those words. A number of Standard Mandarin-speaking and Slavic students participated in the study. All these students had enrolled in intensive ESL classes for an average of 5.2 months and were assessed as beginners by the Canadian Language Benchmarks. Stimuli for the investigations comprised of a list of 30 English progressive verbs containing 10 target Canadian English vowels. Words were also selected to include a range of onsets so as to solve any potential contextual biases in performance. The resulting word list was randomized and a male speaker of Canadian English was recorded producing each word with a five second pause inserted between items.

Biomedical ultrasound imaging from 1 to 1000 mhz

Abstract: Many of the developments in the field of ultrasound imaging are focused on technological improvements to improve the signal to noise of the instrumentation or in the use of new techniques to increase the soft tissue contrast. Contrast in an ultrasound image is based on the strength of backscattered ultrasound. Increase in the transducer bandwidth increases the ultrasound spatial resolution, leading to higher frequencies being used to image smaller structures to provide better axial and lateral resolution. The use of acoustic microscopy has helped in reproducing scattering patterns using smaller diameter beads at frequencies between 100 and 1,000 MHz. Investigations have been conducted using instrumentation that allows ultrasonic interrogation with frequencies ranging between 1-1000 MHz.

Talking while chewing: Speaker response to natural perturbation of speech

Abstract: A study was conducted to investigate the acoustic and articulatory effects of chewing during speech. The proposed that speakers in control of this type of highly complex articulatory perturbation during speech were to show evidence of optimizing to maintain acoustic-auditory speech goals. Acoustic distinctions were expected to be maintained between sibilants when perturbation forced significant articulatory differences in tongue shape. The stimuli consisted of the carrier phrase 'I'm a-----', followed by one of the three words containing the phonemes of interest, such as 'saw', 'shaw', or 'raw'. Stimuli were presented in four blocks for each condition of the investigations, with each block containing four repetitions of each word, resulting in 32 tokens for each word.

Clarifying spectral and temporal dimensions of musical instrument timbre

Abstract: Classic studies based on multi-dimensional scaling of dissimilarity judgments, and on discrimination, for musical instrument sounds have provided converging support for the importance of relatively static, spectral cues to timbre (e.g., energy in the higher harmonics, which has been associated with perceived brightness), as well as dynamic, temporal cues (e.g., rise time, associated with perceived abruptness). Comparatively few studies have evaluated the effects of acoustic attributes on instrument identification, despite the fact that timbre recognition is an important listening goal. To assess the nature, and salience, of these cues to timbre recognition, two experiments were designed to compare discrimination and identification performance for resynthesized tones that systematically varied spectral and temporal parameters between settings for two natural instruments. Stimuli in the first experiment consisted of various combinations of spectral envelopes (manipulating the relative amplitudes of harmonics) and amplitude-vs.-time envelopes (including rise times). Listeners were most sensitive to spectral changes in both discrimination and identification tasks. Only extreme amplitude envelopes impacted performance, suggesting a binary feature based on abruptness of the attack. The second experiment sought to clarify the spectral dimension. Listener sensitivity was compared for a) modifications of spectral envelope shape via variation of formant structure and b) spectral changes that minimally impact envelope shape (using low-pass filters to match the centroids of the formant-varied envelopes). Only differences in formant structure were easily discriminated and contributed strongly to identification. Thus, it appears that listeners primarily identify timbres according to spectral envelope shape. Implications for models of instrument timbre are discussed.

The cocktail party problem: Solutions and applications

Abstract: Some of the significant solutions and application to the cocktail party problem are discussed. Computational Auditory Scene Analysis (CASA) is one of the solutions that is applied to solve the cocktail party problem. The classification procedure is based on simple approximations of four basic principles. These four basic principles include the inaugural time-difference (ITD), interaural intensity difference (IID), and pitch and temporal onset. The ITD can be computed through the cross-correlation and auto-correlation functions, while IID and onset are based on comparisons involving the signal's power envelope.

Digital earplug for brain plasticity research

Abstract: This paper will present the feasibility of utilizing a miniaturized, real-time, in-ear, digital signal processing devices to investigate experience-dependent brain plasticity in the humans. An important component of this trial is the use of a recently developed digital hearing protector (from Sonomax, Montreal, QC) made with a custom earpiece that is instantly fitted to the user's ear, tested for attenuation and then equipped with a miniaturized set of microphone, receiver and Digital Signal Processor. The DSP is a versatile audio platform, originally designed for hearing aid applications, but that has also been successfully programmed for several other applications like a non-linear earplug (offering more attenuation when the ambient noise is higher) and as a musician's earplug (offering a constant attenuation over a wide frequency range together with a loudness correction). The central idea of the current study is to use such digital earplugs to change a person's sound perception, in real-time, in- and outside of the laboratory. Various time and frequency manipulations will be performed on the signal pick-up by the microphone and transmitted to the subject's ear by the receiver, while monitoring the brain plasticity with neuroimaging techniques. Preliminary results using a notch filter demonstrate tonotopic reorganization following sensory modification in the human auditory cortex.

Screech suppression of supersonic jet noise

Abstract: A detailed test program was conducted to evaluate noise generating potential of supersonic jet aircrafts. Screech tone removal was subset of the test program. A number of reflectors having proportional sizes to the nozzle diameters were used in the test program to conduct the investigations. One or three rectangular or chevron shaped tabs were applied as the second mechanism for screech tone removal. The Single tab was effective in attenuating the dominant tone by around 10 dB, while the three chevrons were found to remove the screech tones completely.

Expressing tonal closure in music performance: Auditory and visual cues

Abstract: We examined whether musical performers communicate tonal closure through expressive manipulation of facial expressions and non-pitch features of the acoustic output. Two musicians hummed two versions of Silent Night: one ended on die tonic of the scale and exhibited tonal closure; the other ended on the dominant and was therefore tonally unclosed. In Experiment 1, video-only recordings of the hummed sequences were presented to 15 participants, who judged whether the (imagined) melody was closed or unclosed. Accuracy was reliably above chance, indicating that the musicians expressed tonal closure in facial expressions and listeners decoded these cues. Experiment 2 was conducted to determine whether musicians also communicate tonal closure in acoustic attributes other than pitch. All tones in the hummed melodies were pitched-shifted to a constant mean value, but performances still differed in loudness, microtonal pitch variation, timing, and timbre. Participants judged whether audio-only recordings were closed or unclosed. Accuracy was not above chance overall, but was marginally above chance for judgement of one of the two singers. Results suggest that tonal closure can be mapped onto non-pitch aspects of performance expression, but is primarily restricted to the use of facial expressions.

Loudness prediction model comparison using the equal loudness contours

Abstract: Two of the standardized methods for calculating available steady-state loudness are discussed. The first of these standardized methods is the German standard, called DIN 45631 and the second standardized method is the American ANSI S3.4:2005 standard. The DIN 45631 approach calculates the loudness levels in a similar manner to the 1975 ISO 532B standardized method with minor changes to the procedure. Loudness levels using the German standardized method has been determined directly using the commercially available Bruel & Kjaer PULSE LabShop software. Pure tones have been generated using a B&K 3560 B-Frame and fed back directly into an input channel on the acquisition system to control the signal quality.

Inadequacy of wind turbine noise regulations and their application

Abstract: The inadequacy of existing and new wind turbine noise regulations and their applications in Canada are discussed. Ontario and New Zealand are two jurisdictions that allow the limit of wind turbine noise to increase with an increase in wind speed, but the new draft regulations in Ontario disallow such concessions. The lack of better regulations has forced people living in surrounding areas of noise-making wind turbines. These people continue to suffer from these problems till the offending wind turbines are shut down. The remaining problems are concerned with the large intrusion of turbine noise above ambient and the characteristic swooshing sound of an operating turbine. Other significant problems are related to the excess low frequency noise due to turbine inflow and the neglect of uncertainty in noise prediction.

Establishing normative voice characteristics of younger and older adults

Abstract: A study was conducted to demonstrate the establishment of normative voice characteristics of younger and older adults. It used a new and unique program, called SpeechClinic to record voice samples. SpeechClinic displayed calculated values when a voice sample was recorded. These calculated values included average pitch, length of phonation, and sound pressure level for each task. The algorithms used by the program for performing analyses were well-established and the measured parameters were comparable with most other values. The program allowed the presentation of this information for a given patient, which was useful in monitoring treatment progress. The main objective of the study was to obtain a large number of acoustic voice measures for healthy younger and older adults and provide information about the distribution of these voice characteristics.

Characteristics of wind turbine noise

Abstract: A series of measurements were performed to address the issue associated with the characteristics of wind turbine noise Two different types of wind turbines were monitored under different scenarios to explore the characteristics A low frequency microphone in the operating range of 1 Hz to 10000 Hz was used for the measurement program The main objective of the investigation was to evaluate the presence of low-frequency components below 20 Hz along with the amount of amplitude modulation of the wind turbine noise Two areas, such as Area A and Area B were selected for the measurement program The measurements were recorded for 15 seconds for Area A and 25 seconds for Area B

Architectural Acoustics: Some Historical Developments and Ongoing Issues

Abstract: This paper gives an overview of the history of the development of architectural acoustics and a sampling of the results of several more recent research studies. There are now standardised measures for assessing room acoustics character and there are criteria for room acoustics in terms of these measures. For rooms for speech, such criteria are not so well defined for some special groups of listeners such as the very young or old, hearing impaired listeners, and those listening in a second language. For rooms for musical performance, there is a growing understanding of the more important acoustical characteristics of concert halls, but still a need to improve tools for applying this knowledge to the design of these spaces.

An accurate coupled structural-acoustic analytical framework for the prediction of random and flow-induced noise in transport vehicles: Its Uddation

Abstract: A study was conducted to develop an analytical framework for the prediction turbulent boundary layer (TBL)-induced noise into transport vehicle cabins and validate it A model was proposed that considered the cross pressure power spectral density (PSD) of the stationary and homogeneous TBL wall pressure field over a flat panel, for zero pressure, and in a separate form A number of other models were proposed in the study including a structural model and an acoustic model to conduct more investigations

Development and validation of a sensory-substitution technology for music

Abstract: A study was conducted to investigate aspects of music that were perceived through vibration. The first experiment used the method of limits to measure ability to discriminate the frequency of vibrotactile stimuli across a wide range of frequencies common to music. Investigations revealed that the skin needed to have some degree of frequency discrimination ability for vibrotactile music to be a viable undertaking. A single large conactor was placed on the lower back of each of the 4 participants to conduct the investigations. All anchor and comparison stimuli were equated for subjective intensity in a preliminary experiment. Results indicated that frequency difference limens stimuli presented as a single point of vibration on the back fall between 2 and 3 semitones across the range of vibrotactile sensitivity.

Characterizing flanking transmission paths in the NRC-IRC flanking facility

Abstract: A study was conducted to describe the methodology used in the National Research Council IRC (NRC-IRC) Flanking Facility to systematically measure airborne sound transmission through each flanking path for the 6 junctions of the specimen. The room arrangement in the facility allowed evaluation of 8 horizontal, 4 vertical, 8 diagonal, and 8 cross diagonal pairs of rooms. The floor flanking paths were characterized in the upper rooms of the facility, while the flanking paths of the diagonal and vertical room pairs were estimated using the same methodology. The methodology had its own limitations similar to other measurement methods, despite performing measurements and evaluations.

Binaural objective intelligibility measurement and hearing aids

Abstract: An initial stage was proposed to deal with nonlinear processing and obtain a new binaural objective measure of speech intelligibility in digital hearing aids. The first stage of the binaural measure was based on a simple signal separation scheme used by Hagerman and Olofsson in a monaural investigation of the effects of noise reduction algorithms in hearing aids. It is incorporated into the proposed model with a dual purpose, such as providing separate access to the speech and noise signals at the output of the left and right hearing aids. It served another purpose of dealing with nonlinear signal processing along with complex signal and noise mixtures inside the hearing aid. Signal separation was performed by presenting the speech and noise signals simultaneously to the hearing aid twice, the second time with the phase of the noise reversed.

Acoustic and auditory comparisons of polish and taiwanese mandarin sibilants

Abstract: A study was conducted to compare the acoustic properties of English, Japanese, and Mandarin sibilants in Polish (PL) and Taiwanese Mandarin (TM). The study also discussed the difference in terms of frication noise and the formant transitions along with comparing acoustic properties. It provided acoustic data, including moments, frequencies, formant transitions, and LPC spectra showing there existed the contrasts of the sibilant types in the two languages. The dental sibilant and the alveolo-palatal were in complementary distribution in both languages. A Hanning window of 100ms from the midpoint of each token was selected to produce LPC spectra. The recording sampling rate was 44.1 kHz and the analysis window length was 25ms for conducting the investigations.

Men, women and lenition: Gender differences in the production of intervocalic voiced stops in Mexican Spanish

Abstract: A study was conducted to investigate the effects of gender in the realization of intervocalic in Mexican Spanish. The study conducted a test to demonstrate that significant gender differences existed in the degrees of lenition of the consonants b, d, and g used in Mexican Spanish. Data were collected from a total of six native speakers of a similar variety of the language to conduct the test. Data were collected from an interview where the speakers performed a number of significant tasks. Some of these tasks included a picture identification task and a story-telling task where the speakers were given three sets of sequential pictures and asked to relate the events in each set. These tasks were designed to encourage a casual and conversational style of speech.

Automatic volume settings for environment sensitive hearing aids

Abstract: A study was conducted to demonstrate the automatic adjustment of the hearing aid control settings to minimize the need for manual user interventions. The proposed system was based on computational intelligence tools, such as artificial neural networks and neurofuzzy systems. These systems had the ability to learn the dynamics of highly nonlinear system without the need for having specific knowledge of their mathematical models. These techniques were adopted to map the acoustic features to the desired volume setting of the hearing aid user. A multilayer perceptron (MLP) and an adaptive network-based fuzzy inference system (ANFIS) were analyzed as two computational intelligence tools on three simulated users. These simulated users were suffering from moderate, severe, and profound hearing losses.

Nrc-Irc flanking sound transmission facility

Abstract: Researchers from the National Research Council designed and built a flanking facility to investigate the way flanking paths affected the sound insulation performance of building systems The facility had a number of specific features to help the researchers conduct the investigations The research facility had 8 rooms or 8 walls, 4 floors, and 6 junctions, enabling evaluation flanking of bearing and non-bearing wall and floor junctions, along with wall paths with a single specimen Fixed surfaces were large and isolated from one another using resilient mountings to ensure that the facility did not contribute to vibration transmission Each room had a volume that differed by around 10% from adjacent rooms to avoid modal matching and follow the recommendations of ISO 140 standard The entire facility was also run by a computer system that controlled noise sources, robot movements, and signal capture

Effects of structural load and joist type on flanking sound transmission

Abstract: A study was conducted to investigate the effects of structural load and joist type on flanking sound transmission in the NRC flanking facilities. Measurements were performed at two NRC flanking facilities, such as he first generation four-room and second generation eight-room facilities to assess the effects of these parameters. The appropriate surfaces of the rooms were shielded to limit the sound transmission to the paths being investigated. The first part of the study dealt with the reproducibility of load and general tendency of the effect of loading. The second part dealt with the effect of loading relative to joist orientation and continuity. The initial study investigated flanking sound transmission experienced between two horizontally separated rooms with discontinuous joists perpendicular to the separating wall.

Transfer path analysis using engine radiated sound and mount vibration

Abstract: A study was conducted to perform transfer path analysis using engine radiated sound and mount vibration. The study conducted investigations that had a number of objectives. One of these objectives involved developing a vehicle interior sound and vibration numerical estimation method. The method was based on engine radiated sound and mount vibration and verifying the estimations by actual vehicle interior sound and vibration measurements at all operating conditions. Another objective involved evaluating the contribution of individual engine air-borne and structure-borne source of vibration to the total vehicle interior sound and vibration. Investigations revealed that the vehicle interior sound and vibration was a combination of air-borne and structure-borne transfer paths.

Old and new cochlear maps

Abstract: A study was conducted to present two new categories of cochlear maps related to the impedance function Z BM (x, f). The active peak (AP) map was determined from experimental curves of less than 20-dB of basilar-membrane (BM) velocity amplitude against x or f. The guinea-pig map, the AP map, and the mentioned BM length of L= 18.5 mm were based on earlier research.

Effects of acoustic interaction between the subglottic and supraglottic cavities of the human phonatory system

Abstract: The purpose of this work, is to describe the effects of the coupling of the subglottic and supra glottic cavities of the human phonatory apparatus. For this, we will determine and use the transfer function of the vocal tract evaluated owing to an exploration of the human phonatory system using an external excitation using a pseudorandom sequence; this method was developed by Djeradi et. al. 1991. This evaluation will be carried out on the basis of the following three conditions of the glottis: open glottis, closed glottis and variable glottis. One of the advantages of this method will be used, indeed, it is possible, at the time of the same expiry phase that corresponding to a sustained articulatory configuration, to record the signal of the sound itself and the useful signal for the measurement of the transfer function. The comparison of the various spectral data thus obtained highlights the subglottic effects of coupling on the one hand and shows that the conditions at the glottis have an influence on the resonances of the supraglottic cavities on the other hand. This enabled us highlight an increase in the value of the resonance frequencies, of the band-widths and a modification of the deviation between the resonances of the vocal tract. We have also noted the appearance of additional resonances peaks that can correspond to subglottic cavities During the second phase, we reproduced these effects by simulations on geometrical configurations obtained by the X- rays method performed on the same person and for the same configurations.

Bayesian ocean acoustic source track with environmental uncertainty

Abstract: A study was conducted to explore matched-field tracking of a moving acoustic source in the ocean when acoustical properties of the environment are poorly known. The goal was to determine track uncertainty distributions, quantifying the information content of the tracking process. Source information was extracted from the posterior probability density (PPD) by integrating over unknown environmental parameters. Source information was extracted to obtain a time-ordered series of joint marginal probability surfaces over source range and depth. Marginal PPDs were computed numerically using efficient Markov-chain Monte Carlo (MCMC) methods, including Metropolis-Hastings sampling over environmental parameters and heat-bath Gibbs sampling over source locations.