Showing papers on "Noise published in 2010"

Immediate spectral flexibility in singing chiffchaffs during experimental exposure to highway noise

Abstract: Sound plays an important role in the life of many animals, including many bird species. Typically, male birds sing to defend a territory and to attract mates. Ambient noise may negatively affect the signal efficiency of their songs, which may be critical to reproductive success. Consequently, anthropogenic noise may be detrimental to individual birds and to populations in cities and along highways. Several bird species that are still common in urban areas have been shown to sing at higher frequency at locations where there is more low-frequency traffic noise. Here we show that chiffchaffs along noisy highways also sing with a higher minimum frequency than chiffchaffs nearby at a quiet riverside. Furthermore, through experimental exposure to highway noise we show that these birds are capable of making such adjustments over a very short time scale. The first 10 songs sung during the noise exposure revealed an immediate shift to higher frequencies, with a return to pre-exposure levels in recordings without noise the following day. In a transmission re-recording experiment we tested the impact of a potential measurement artifact by recording playback of the same songs repeatedly under different controlled noise conditions. We found an upward shift in the minimum frequency measurement associated with more noisy recordings of the same song, but this artifact was not of a scale that it could explain the noise-dependent spectral shifts in chiffchaffs.

Plasticity in the vocalizations of anurans in response to traffic noise

Abstract: Many species use acoustic signals to attract mates, and such signals can be degraded by anthropogenic noise. Anuran abundance has been shown to be negatively correlated with road traffic which could be due in part to the interruption of mate attraction by traffic noise. However, this impact could be small if anurans can alter their vocalization characteristics to avoid masking of their calls by traffic noise. We predicted that: (i) anuran vocalization characteristics (dominant frequency, mean amplitude and call rate) should be different in areas with different traffic noise levels; (ii) increases in traffic noise can cause immediate changes in amphibian vocalization characteristics; (iii) these altered vocalizations are similar to those at high traffic sites. To test the first prediction we compared vocalizations of four species of anuran at breeding sites in locations with low traffic noise vs. sites with high traffic noise. For the second prediction we broadcast traffic noise at low traffic (quiet) sites, and compared the anuran vocalizations before vs. during the broadcast traffic noise. For the third prediction we compared vocalizations at high traffic sites to those produced at low traffic sites while broadcasting traffic noise. Three species of anurans found at locations with low traffic noise produced vocalizations with different characteristics than individuals of the same species found in locations with high traffic noise. Broadcast traffic noise immediately altered amphibian vocalization characteristics such that they became similar to those of the same species found in locations with high traffic noise. We conclude that plasticity in the vocalizations of anurans allows for the maintenance of acoustic communication in the presence of traffic noise.

Suppressing noise in an audio signal

Abstract: An electronic device for suppressing noise in an audio signal is described. The electronic device includes a processor and instructions stored in memory. The electronic device receives an input audio signal and computes an overall noise estimate based on a stationary noise estimate, a non-stationary noise estimate and an excess noise estimate. The electronic device also computes an adaptive factor based on an input Signal-to-Noise Ratio (SNR) and one or more SNR limits. A set of gains is also computed using a spectral expansion gain function. The spectral expansion gain function is based on the overall noise estimate and the adaptive factor. The electronic device also applies the set of gains to the input audio signal to produce a noise-suppressed audio signal and provides the noise-suppressed audio signal.

Method and system for a multi-microphone noise reduction

Abstract: A method for a multi microphone noise reduction in a complex noisy environment is proposed. A left and a right noise power spectral density for a left and a right noise input frame is estimated for computing a diffuse noise gain. A target speech power spectral density is extracted from the noise input frame. A directional noise gain is calculated from the target speech power spectral density and the noise power spectral density. The noisy input frame is filtered by Kalman filtering method. A Kalman based gain is generated from the Kalman filtered noisy frame and the noise power spectral density. A spectral enhancement gain is computed by combining the diffuse noise gain, the directional noise gain, and the Kalman based gain. The method reduces different combinations of diverse background noise and increases speech intelligibility, while guaranteeing to preserve the interaural cues of the target speech and directional background noises.

Attractive "Quiet" Courtyards: A Potential Modifier of Urban Residents' Responses to Road Traffic Noise?

Abstract: The present paper explores the influence of the physical environmental qualities of “quiet” courtyards (degree of naturalness and utilization) on residents’ noise responses. A questionnaire study was conducted in urban residential areas with road-traffic noise exposure between LAeq,24h 58 to 68 dB at the most exposed facade. The dwellings had “quiet” indoor section/s and faced a “quiet” outdoor courtyard (LAeq,24h < 48 dB facade reflex included). Data were collected from 385 residents and four groups were formed based on sound-level categories (58–62 and 63–68 dB) and classification of the “quiet” courtyards into groups with low and high physical environmental quality. At both sound-level categories, the results indicate that access to high-quality “quiet” courtyards is associated with less noise annoyance and noise-disturbed outdoor activities among the residents. Compared to low-quality “quiet” courtyards, high-quality courtyards can function as an attractive restorative environment providing residents with a positive soundscape, opportunities for rest, relaxation and play as well as social relations that potentially reduce the adverse effects of noise. However, access to quietness and a high-quality courtyard can only compensate partly for high sound levels at facades facing the streets, thus, 16% and 29% were still noise annoyed at 58–62 and 63–68 dB, respectively. Implications of the “quiet”-side concept are discussed.

Predictive characterization of adjacent track erasure in recording media

Abstract: A wide area track erasure (WATER) rate of change is determined from a model generated from a plurality of track erasure measurements performed on a magnetic recording media. A model of the change in noise amplitude for an off-track position as a function of the number of aggressor track writes employed in the track erasure measurements is generated. In a log-linear space a linear fit of the change in noise amplitude with respect to the number of aggressor track writes yields a rate of noise amplitude change (dB/decade) which may be utilized to rank magnetic recording media.

Evoked response of heart rate variability using short-duration white noise.

Abstract: To investigate and to establish a model for evaluation of the instant cardiovascular responses to the noises of low-to-moderate intensity, sixteen healthy subjects were enrolled. The white noises were binaurally presented with a supra-aural earphone. The test intensities of noises were no noise, 50, 60, 70 and 80 dBA. Each noise was continued for 5 min and the electrocardiogram was simultaneously recorded. The cardiac autonomic responses were evaluated using power spectral analysis of the R–R contour obtained from digital signal processing of the ECG tracings. The result showed that the mean heart rate and mean blood pressure did not change significantly with the noises. However, the low-frequency power (LF) which represents cardiac autonomic modulations and the ratio (LHR) of LF to high-frequency power (HF) which reflects cardiac sympathetic modulations were significantly greater in the noise intensity of 50, 60, 70 and 80 dBA (p

Audio forensics from acoustic reverberation

Abstract: An audio recording is subject to a number of possible distortions and artifacts. For example, the persistence of sound, due to multiple reflections from various surfaces in a room, causes temporal and spectral smearing of the recorded sound. This distortion is referred to as audio reverberation time. We describe a technique to model and estimate the amount of reverberation in an audio recording. Because reverberation depends on the shape and composition of a room, differences in the estimated reverberation can be used in a forensic and ballistic setting.

Clubbing: The cumulative effect of noise exposure from attendance at dance clubs and night clubs on whole-of-life noise exposure

Abstract: Anecdotally it has been suggested that exposure to some noise sources through leisure activities could have a significant effect on whole-of-life noise exposure. While exposure levels do vary, a typical night club or dance club attendee was found to experience an equivalent continuous A-weighted noise level of around 98 dB for up to 5 hours with an exposure of 12.2 Pa 2 h. This can extend up to 104 Pa 2 h in extreme cases. A study of clubbers reveals regular clubbing to be a source of high noise exposure, with a sustained period of regular club attendance contributing to a significant portion of whole-of-life noise exposure.

Evaluating water sounds to improve the soundscape of urban areas affected by traffic noise

Abstract: The acoustic characteristics of various kinds of water sounds were investigated to evaluate their suitability for improving the soundscape with road traffic in urban spaces. Audio recordings were made in urban spaces with water features such as fountains, streams, water sculptures, or waterfalls. The temporal and spectral aspects of the sounds were clarified, and subjective evaluations were performed to find the proper level difference between water sounds and road traffic noise for making urban soundscape more subjectively pleasant. The results indicated that the perceptual difference of the water sound level was around 3 dB with noises from road traffic in the background. The water sound, which had 3 dB less sound pressure level, was evaluated as preferable when the levels of road traffic noise were 55 or 75 dBA. It was also found that water sounds with relatively greater energy in low-frequency ranges were effective for masking noise caused by road traffic. The results of the present study will be valuable to urban designers and planners by providing guidelines for improving design solutions for water features in urban soundscape

Recursive Closed-Form Optimization of Spectral Audio Power Allocation for Near End Listening Enhancement

Abstract: In mobile telephony, near end listening enhancement is desired by the near end listener who perceives not only the clean far end speech but also ambient background noise. A typical scenario is mobile telephony in acoustical background noise such as traffic or babble noise. In such a situation, it is often not acceptable/possible to increase the audio power. In this contribution we analyse the calculation rules of the Speech Intelligibility Index (SII) and develop a recursive closedform solution which maximizes the SII under the constraint of an unchanged average power of the audio signal. This solution has very low complexity compared to a previous approach of the authors and is thus suitable for real-time processing.

Interrupted speech perception: The effects of hearing sensitivity and frequency resolution

Abstract: Jin & Nelson (2006) found that although amplified speech recognition performance of hearing-impaired (HI) listeners was equal to that of normal-hearing (NH) listeners in quiet and in steady noise, nevertheless HI listeners' performance was significantly poorer in modulated noise. As a follow-up, the current study investigated whether three factors, auditory integration, low-mid frequency audibility and auditory filter bandwidths, might contribute to reduced sentence recognition of HI listeners in the presence of modulated interference. Three findings emerged. First, sentence recognition in modulated noise found in Jin & Nelson (2006) was highly correlated with perception of sentences interrupted by silent gaps. This suggests that understanding speech interrupted by either noise or silent gaps require similar perceptual integration of speech fragments available either in the dips of a gated noise or across silent gaps of an interrupted speech signal. Second, those listeners with greatest hearing losses in the low frequencies were poorest at understanding interrupted sentences. Third, low-to mid-frequency hearing thresholds accounted for most of the variability in Masking Release (MR) for HI listeners. As suggested by Oxenham and his colleagues (2003 and 2009), low-frequency information within speech plays an important role in the perceptual segregation of speech from competing background noise.

The Potential of Natural Sounds to Mask Wind Turbine Noise

Abstract: Wind turbine (WT) noise may cause annoyance, especially in relatively quiet areas with low ambient levels. As a compliment to conventional noise control at the source, addition of wanted sounds may ...

Digital audio forensics using background noise

Abstract: This paper presents a new audio forensics method based on background noise in the audio signals. The traditional speech enhancement algorithms improve the quality of speech signals, however, existing methods leave traces of speech in the removed noise. Estimated noise using these existing methods contains traces of speech signal, also known as leakage signal. Although this speech leakage signal has low SNR, yet it can be perceived easily by listening to the estimated noise signal, it therefore cannot be used for audio forensics applications. For reliable audio authentication, a better noise estimation method is desirable. To achieve this goal, a two-step framework is proposed to estimate the background noise with minimal speech leakage signal. A correlation based similarity measure is then applied to determine the integrity of speech signal. The proposed method has been evaluated for different speech signals recorded in various environments. The results show that it performs better than the existing speech enhancement algorithms with significant improvement in terms of SNR value.

Near end listening enhancement optimized with respect to speech intelligibility index and audio power limitations

Abstract: In speech communications, signal processing algorithms for near end listening enhancement allow to improve the intelligibility of clean (far end) speech for the near end listener who perceives not only the far end speech but also ambient background noise A typical scenario is mobile telephony in acoustical background noise such as traffic or babble noise In these situations, it is often not acceptable/possible to increase the audio power amplification In this contribution we use a theoretical analysis of the Speech Intelligibility Index (SII) to develop an algorithm which numerically maximizes the SII under the constraint of an unchanged average power of the audio signal

Noise-induced annoyance from transportation noise: short-term responses to a single noise source in a laboratory.

Abstract: An experimental study was performed to compare the annoyances from civil-aircraft noise, military-aircraft noise, railway noise, and road-traffic noise. Two-way within-subjects designs were applied in this research. Fifty-two subjects, who were naive listeners, were given various stimuli with varying levels through a headphone in an anechoic chamber. Regardless of the frequency weighting network, even under the same average energy level, civil-aircraft noise was the most annoying, followed by military-aircraft noise, railway noise, and road-traffic noise. In particular, penalties in the time-averaged, A-weighted sound level (TAL) of about 8, 5, and 5 dB, respectively, were found in the civil-aircraft, military-aircraft, and railway noises. The reason could be clarified through the high-frequency component and the variability in the level. When people were exposed to sounds with the same maximum A-weighted level, a railway bonus of about 3 dB was found. However, transportation noise has been evaluated by the time-averaged A-weighted level in most countries. Therefore, in the present situation, the railway bonus is not acceptable for railway vehicles with diesel-electric engines.

Effects of noise, nonlinear processing, and linear filtering on perceived speech quality.

Abstract: Objectives The purpose of this study was to measure subjective quality ratings in listeners with normal hearing and listeners with hearing loss for speech subjected to a wide range of processing conditions that are representative of real hearing aids. Design Speech quality was assessed using a rating scale in a group of 14 listeners with normal hearing and 15 listeners with mild to moderately severe sensorineural hearing loss. Controlled simulations of hearing aid processing were used to process speech that included speech subjected to (1) noise and nonlinear processing, (2) linear filtering, and (3) combinations of noise, nonlinear processing, and linear filtering. The 32 conditions of noise and nonlinear processing included stationary speech-shaped nose, multitalker babble, peak clipping, quantization noise, spectral subtraction, and dynamic range compression (in quiet, with babble, and with spectral subtraction). The 32 linear filtering conditions included high-pass filtering, low-pass filtering, band-pass filtering, positive and negative spectral tilt, and resonance peaks. Subsets of these conditions were used for the 36 conditions that combined noise and nonlinear processing with linear processing. Results Both listeners with normal hearing and listeners with hearing loss gave consistent (reliable) ratings. In both listener groups, sound quality was significantly affected by the noise, nonlinear processing, and linear filtering conditions. Compared with the listeners with normal hearing, the listeners with hearing loss showed significantly lower ratings of sound quality in nearly all of the processing conditions. For the conditions included in the current hearing aid simulation, noise and nonlinear conditions had a greater effect on quality judgments than did the linear filtering conditions. Conclusions The data reported here provide a comprehensive dataset of speech quality ratings for simulated hearing aid processing conditions. The results indicate that quality ratings by listeners with hearing loss are significantly lower than quality ratings by listeners with normal hearing. In addition, quality ratings by listeners with hearing loss are impacted by signal processing at least as much as, and often more than, the quality ratings by listeners with normal hearing. Finally, quality ratings for speech processed with a simulated hearing aid are impacted more by noise and nonlinear signal processing than by linear filtering.

Noise detection and reduction in audio devices

Abstract: Methods and apparatuses for detection and reduction of wind noise in audio devices are disclosed. In an embodiment, a method includes acquiring and transforming the audio signals. Correlations from the transformed audio signals are computed. A cross correlation index is compared to a predetermined value to determine if a wind noise spectral content is present. In another embodiment, an apparatus includes an audio processing unit to receive non-decomposed audio signals, and an audio decomposition unit to receive the non-decomposed audio signals and to generate decomposed audio signals. A wind noise spectrum estimation unit receives non-decomposed audio signals and decomposed audio signals and identifies wind noise spectral components in at least one of the non-decomposed and decomposed audio signals. A wind noise spectrum reduction unit receives the wind noise spectral components and removes the wind noise spectral components from at least one of the non-decomposed and the decomposed audio signals.

Robust audio identification for MP3 popular music

Abstract: Audio identification via fingerprint has been an active research field with wide applications for years. Many technical papers were published and commercial software systems were also employed. However, most of these previously reported methods work on the raw audio format in spite of the fact that nowadays compressed format audio, especially MP3 music, has grown into the dominant way to store on personal computers and transmit on the Internet. It would be interesting if a compressed unknown audio fragment is able to be directly recognized from the database without the fussy and time-consuming decompression-identification-recompression procedure. So far, very few algorithms run directly in the compressed domain for music information retrieval, and most of them take advantage of MDCT coefficients or derived energy type of features. As a first attempt, we propose in this paper utilizing compressed-domain spectral entropy as the audio feature to implement a novel audio fingerprinting algorithm. The compressed songs stored in a music database and the possibly distorted compressed query excerpts are first partially decompressed to obtain the MDCT coefficients as the intermediate result. Then by grouping granules into longer blocks, remapping the MDCT coefficients into 192 new frequency lines to unify the frequency distribution of long and short windows, and defining 9 new subbands which cover the main frequency bandwidth of popular songs in accordance with the scale-factor bands of short windows, we calculate the spectral entropy of all consecutive blocks and come to the final fingerprint sequence by means of magnitude relationship modeling. Experiments show that such fingerprints exhibit strong robustness against various audio signal distortions like recompression, noise interference, echo addition, equalization, band-pass filtering, pitch shifting, and slight time-scale modification etc. For 5s-long query examples which might be severely degraded, an average top-five retrieval precision rate of more than 90% can be obtained in our test data set composed of 1822 popular songs.

Musical-noise analysis in methods of integrating microphone array and spectral subtraction based on higher-order statistics

Abstract: We conduct an objective analysis on musical noise generated by two methods of integrating microphone array signal processing and spectral subtraction. To obtain better noise reduction, methods of integrating microphone array signal processing and nonlinear signal processing have been researched. However, nonlinear signal processing often generates musical noise. Since such musical noise causes discomfort to users, it is desirable that musical noise is mitigated. Moreover, it has been recently reported that higherorder statistics are strongly related to the amount of musical noise generated. This implies that it is possible to optimize the integration method from the viewpoint of not only noise reduction performance but also the amount of musical noise generated. Thus, we analyze the simplest methods of integration, that is, the delay-and-sum beamformer and spectral subtraction, and fully clarify the features of musical noise generated by each method. As a result, it is clarified that a specific structure of integration is preferable from the viewpoint of the amount of generated musical noise. The validity of the analysis is shown via a computer simulation and a subjective evaluation.

Audio Steganography Using Bit Modification - A Tradeoff on Perceptibility and Data Robustness for Large Payload Audio Embedding

Abstract: Audio steganography using bit modification of time domain audio samples is a simple technique for multimedia data embedding with potential for large payload. Depending on the index of the bit used to modify the samples in accordance with the data to be hidden, the resulting stego audio signal may become perceptible and/or susceptible to incorrect retrieval of the hidden data. This paper presents some results of the tradeoff between the conflicting requirements of data robustness, payload and imperceptibility. Experimental results on both clean and noisy host audio signals indicate that while the payload can be as high as over 3000 bits/s - much higher rate than common audio data embedding techniques - noticeability of embedding is decreased and noise tolerance increased by using higher bit indices than the traditional least significant bit. Bit error rates of below one percent were observed for data retrieved from noise-added stego audio signals with 39 dB of SNR for an embedded payload of over 10 Kbits in a 3.3 s host audio.

Stand-alone ear bud for active noise reduction

Abstract: An ear bud and noise reduction system actively reduce noise in one ear while the user listens with the other ear to an audio sound wave produced by the speaker of an electronic device (e.g., a cell phone or a wireless headset attachable to a single ear). The ear bud includes a microphone, an active noise reduction unit, and an audio speaker. The active noise reduction unit produces a noise reduction signal based on ambient noise sensed by the microphone in the vicinity of a first ear while an electronic device produces a first audio sound wave in the vicinity of a second ear. The audio speaker produces a second audio sound wave in the vicinity of the first ear based on the noise reduction signal to reduce or substantially cancel the ambient noise. The first and second audio sound waves may be produced independently of each other.

Sub-fingerprint masking for a robust audio fingerprinting system in a real-noise environment for portable consumer devices

Abstract: The robustness of audio fingerprinting system in a noisy environment is a principal challenge in the area of content-based music retrieval, especially for use in portable consumer devices. Our new audio fingerprint method using sub-fingerprint masking based on the predominant pitch extraction dramatically increases the accuracy of the audio fingerprinting system in a noisy environment, while requiring much less computing power for matching, compared to the expanded hash table lookup method, where the searching complexity increases by the factor of 33 times the degree of expansion.

Estimation of a white Gaussian noise in the Short Time Fourier Transform based on the spectral kurtosis of the minimal statistics: Application to underwater noise

Abstract: In this paper we present a noise level estimator using minimal values of the Short Time Fourier Transform of a signal embedded in a white Gaussian noise. The spectral kurtosis of the smallest values is used to estimate the variance of the noise without any a priori knowledge on the signal. This estimation is illustrated on both a synthetic and speech signal. A dolphin whistle detection in underwater noise is given as an application.

The influence of indoor acoustical parameters on student perception in classrooms

Abstract: This study presents the results of a field study carried out at high schools to determine the effects of both indoor and outdoor noise levels on educational quality. Two schools having the highest outdoor noise levels due to dense commercial facility and car traffic in Istanbul were selected for the study from among 67 schools. The noise survey studies were conducted in both occupied and unoccupied classrooms. Noise measurements were also conducted with the windows open and closed. A-weighted outdoor noise levels were between 74�80 dB (Leq, for one hour in a day and five different time periods) at the facades of classrooms. Indoor noise levels varied between 60 and 63 dBA (Leq, h/day) when the classrooms were occupied. Comparisons of measured and recommended levels are made. Degrees of annoyance and dissatisfaction obtained for the above comparisons are determined for the classrooms by a questionnaire to test the statistical meaning of the measured results.

Audio encoding and decoding method, system and noise level estimation method

Abstract: The invention relates to an audio encoding and decoding method, a system and a noise level estimation method, and the noise level estimation method comprises the following steps: estimating a power spectrum of audio signals to be encoded according to a frequency domain coefficient of the audio signals to be encoded; and estimating noise level of the audio signals of a zero-bit encoding sub-band according to the calculated power spectrum, wherein the noise level is used for controlling the ratio of energy for noise filling to the energy for frequency band replication during decoding, and the zero-bit encoding sub-band refers to the encoding sub-band of which the distributed number of bits is zero. By adopting the method in the invention, the frequency domain coefficient which is not encoded can be well re-constructed.

Audio Production and Critical Listening: Technical Ear Training

Abstract: Introduction 1 Listening 1.1 Everyday Listening 1.2 What is Technical Ear Training? 1.3 What is Timbre? 1.4 Shaping Sounds 1.5 Sound Reproduction System Configurations 1.6 The Listening Environment 2 Spectral Balance and Equalization 2.1 Types of Filters and Equalizers 2.2 Practice 2.3 Exercises 3 Spatial Attributes 3.1 Time Delay 3.2 Reverberation 3.3 Delay and Comb Filtering 3.4 Reverberation in Multichannel Audio 3.5 Description of the Software Training Module 3.6 Mid-Side Matrixing, Stereo Shuffling, and Polarity Reversal 3.7 Summary 4 Dynamic Range and Levels 4.1 Level Changes 4.2 Compressors and Limiters 4.3 Expanders and Gates 5 Distortion and Noise 5.1 Clipping and Overdrive 5.2 Noise, Hum and Buzz 5.3 Quantization Distortion: Bit Rate Reduction 6 Amplitude Envelope 6.1 Digital Audio Editing: The Source-Destination Technique 6.2 Software Exercise Module 6.3 Focus of the Exercise 6.4 Conclusions 7 Analysis of Sound 7.1 Analysis of Sound from Electroacoustic Sources 7.2 Graphical Analysis of Sound 7.3 Multichannel Audio 7.4 Selecting Listening Material 7.5 Analysis Examples 7.6 Sound Enhancers on Media Players 7.7 Analysis of Sound from Acoustic Sources 7.8 Conclusions A About the software practice modules Bibliography

Associations between chronic community noise exposure and blood pressure at rest and during acute noise and non-noise stressors among urban school children in India

Abstract: The present study builds on prior research that has examined the association between children’s chronic exposure to community noise and resting blood pressure and blood pressure dysregulation during exposure to acute stressors. A novel contribution of the study is that it examines how chronic noise exposure relates to blood pressure responses during exposure to both noise and non-noise acute stressors. The acute noise stressor was recorded street noise and the non-noise stressor was mental arithmetic. The sample consisted of 189 3rd and 6th grade children (51.9% percent boys; 52.9% 3rd graders) from a noisy (n = 95) or relatively quiet (n = 94) public school in the city of Pune, India. There were no statistically significant differences between chronic noise levels and resting blood pressure levels. However, relative to quiet-school children, noisy-school children had significantly lower increases in blood pressure when exposed to either an acute noise or non-noise stressor. This finding suggests that chronic noise exposure may result in hypo-reactivity to a variety of stressors and not just habituation to noise stressors.