Showing papers on "Noise published in 1990"

Auditory Detection, Discrimination and Speech Processing in Ageing, Noise-sensitive and Hearing-impaired Listeners

Abstract: The aims of this research were to document changes in hearing and speech intelligibility in noise that occur with ageing, noise sensitivity, and progressive bilateral sensorineural hearing loss. Five groups defined by age, clinical complaint and degree of hearing loss were tested. Each of 73 subjects participated in nine different procedures, including detection in quiet and in continuous 90 dB SPL helicopter noise, frequency and duration discrimination, consonant recognition and word identification. The effects of different types of background noise and speech-to-noise ratio were investigated. Ageing, without concomitant hearing loss, resulted in significantly greater DLs both for frequency and for duration with a 20 ms standard at both 500 Hz and 4000 Hz. Hearing loss, unconfounded by ageing, affected masked detection and frequency discrimination at 4000 Hz and speech intelligibility in noise. The sole finding for subjects with noise sensitivity was an upward spread of masking for detection. Across test...

Effect of noise on word discrimination by subjects with impaired hearing, compared with those with normal hearing.

Abstract: A comparison was made of the discrimination ability of different groups of hearing-impaired and normal-hearing subjects in noisy conditions. Four groups of subjects having a sensorineural hearing loss with various audiogram configurations, one group of subjects having a conductive hearing loss and one group of normal-hearing subjects were chosen. The submaster tapes were recorded in quiet and in pink noise with signal-to-noise ratios of -3, -8, and -13 dB. The test subjects heard the test words monaurally via earphones. The best speech discrimination was achieved in quiet, anechoic conditions. As the noise level increased, speech discrimination decreased. Subjects with sensorineural hearing loss were more adversely affected by noise than subjects with normal hearing or with conductive hearing loss. However, at high noise levels, their speech discrimination was poorer than that of normal-hearing subjects. Persons with a high-frequency hearing loss, cut-off point 1 kHz, suffered in noise similarly to those with sloping or flat hearing losses. In quiet and in moderate noise, the speech discrimination of subjects with a conductive hearing loss and subjects with normal hearing was similar, while at high noise levels, subjects with conductive hearing losses achieved better discrimination than normal-hearing subjects.

Dynamic noise reduction and spectral restoration system

Abstract: An audio processor consisting of a "single-ended" dynamic noise reduction system cascaded and cross-coupled with a program-adaptive dynamic equalizer. The audio at the output has a consistent subjective spectral texture even if the spectral texture of the input audio varies widely. Further, although the system often adds high frquency energy to the audio, it does not increase the perceived noise level and is free from audible noise modulation.

Apparatus for the muting of an audio power amplifier in a standby mode

Abstract: In a television receiver apparatus is provided for muting an audio power amplifier having continuous operating supply voltage applied thereto from a standby power supply even when the receiver is in an "off" condition so that spurious noise and hum coupled to the power amplifier will not be amplified and heard by the viewer. The muting is applied via a microprocessor controller which controls and senses the power supply status of the receiver as well as mutes the power amplifier in both the "off" and the "on" conditions.

Apparatus for recording and/or reproducing video and audio signals

Abstract: For providing high-quality reproduction of audio in a video tape recorder (VTR), the video and audio signals are recorded as first and second mixed signals in successive alternately arranged adjacent first and second parallel record tracks, respectively, extending obliquely on a magnetic record tape, with the first and second mixed signals being comprised of respective carriers of different frequencies which are modulated by an audio signal to constitute respective FM audio signals mixed with a video signal. In a normal reproducing mode of the VTR, in which the tape is advanced at a normal speed corresponding to that used for recording, magnetic heads scan substantially along the adjacent first and second record tracks in succession for alternately reproducing the first and second mixed signals therefrom, the FM audio signals are separated from the reproduced mixed signals and then are demodulated for obtaining therefrom respective alternately reproduced portions of the audio signal, and the alternately reproduced portions are sequentially combined to reconstitute the audio signal therefrom. In another reproducing mode in which the tape is advanced at other than its normal speed, the heads scan imperfectly along the record tracks so that the mixed signals are reproduced therefrom with noise particularly when the heads are situated adjacent end portions of the tracks being imperfectly scanned, and a noise compensating circuit is operative, in that other reproducing mode, for removing the noise from the reconstituted audio signal.

Automatic volume control circuit

Abstract: An electronic circuit for automatically adjusting the volume of an audio program in accordance with changes in the magnitude of ambient noise is disclosed A voltage signal is generated which is proportional to the magnitude of the ambient noise The voltage signal is applied to the cathode of a diode The anode of the diode is connected through a capacitor to ground potential The anode of the diode is also connected to a variable resistance device, which controls the volume of the audio program in accordance with the voltage across the capacitor When the magnitude of the ambient noise increases, the capacitor is slowly charged by the leakage current passing through the reversed biased diode As a result, the volume of the audio program is slowly increased When the magnitude of such noise decreases, the capacitor is rapidly discharged through the forward biased diode Thus, the volume of the audio program is rapidly decreased

Control device for air conditioner

Abstract: PURPOSE:To control a room temperature including a quantity of heat generated from the physical action state of users and machines by a method wherein based on an output signal from a sound volume detecting means in a room, the number of users and a quantity of heat of a machine are determined, a necessary total quantity of heat is computed therefrom, and control is effected according to the computed result. CONSTITUTION:An audio signal obtained through the collection of a sound by means of an audio level detecting means 1 is amplified by an amplifier 2. A sensitivity regulating means 7 regulates the gain (amplification degree) of the amplifier 2. For example, the gain of the amplifier 2 is switched to three stages: 'loud voice', 'ordinary voice', and 'a low voice' according to the use of the room. This method detects the number of users in the room by means of the audio level according to the use condition of the interior of the room. When a machine with a high calorific value is a main factor by which an increase in the room temperature is caused, the pass band of a band pass filter 3 is set by a filter band set means 8 so that only noise generated by the machine passes. A signal processed thus described is fed to a microcomputer 4, and is converted to heat energy responding to the number of users and the level of noise of the machine.

Masking of tone bursts by modulated noise in normal, noise-masked normal, and hearing-impaired listeners.

Abstract: Threshold of 4.6-ms tone bursts was measured in quiet and in the presence of a 100% sinusoidally amplitude-modulated speech-shaped noise. For the modulated-noise conditions, the onset of the tone b...

Oversampled Analog-to-Digital Conversion for Digital Audio Systems

Abstract: It relies on the techniques of spectral noise shaping and oversampling. This encoding is based on higher order delta-sigma modulation and is referred to as HLDSM A/D conversion. A hardware version of this system was developed measuring 80-dB SQNR and 0.007% total harmonic distortion

Masker fringe and binaural detection.

Abstract: Yost [J. Acoust. Soc. Am. 78, 901–907 (1985)] found that the detectability of a 30‐ms dichotic signal (Sπ) in a 30‐ms diotic noise (No) was not affected by the presence of a 500‐ms dichotic forward fringe (Nπ). Kollmeier and Gilkey [J. Acoust. Soc. Am. 87, 1709–1719, (1990)] performed a somewhat different experiment and varied the onset time of a 25‐ms Sπ signal in a 750‐ms noise that switched, after 375‐ms, from Nπ to No. In contrast to Yost, they found that the Nπ segment of the noise reduced the detectability of the signal even when the signal was temporally delayed well into the No segment of the noise and suggested that the Nπ segment of noise acted as a forward masker. To resolve this apparent conflict, the present study investigated the detectability of a brief Sπ signal in the presence of an No masker of the same duration as the signal. The masker was preceded by quiet or an Nπ forward fringe and followed by quiet, an No, or Nπ backward fringe. The present study differs from most previous studies ...

Intra-vehicle speech device

Abstract: PURPOSE:To clearly hold conversation between a driver at a driver seat and a passenger at a rear seat by vocalizing the voice of the driver collected with a microphone in the neighborhood of the driver seat from a speaker in the neighborhood of the rear seat, and vocalizing that of the passenger at the rear seat collected with the microphone in the neighborhood of the rear seat from the speaker in the neighborhood of the driver seat. CONSTITUTION:A voice signal from the microphone M1 in the neighborhood of the driver seat S1 is derived from a microphone amplifier A11 to the speaker SP2 via a power amplifier circuit A22, and the voice of the driver can be vocalized from the speaker SP2 in the neighborhood of the rear seats S3-S6 in such way. Similarly, the voice signal from the microphone N2 in the neighborhood of the rear seats S3-S6 is derived from a microphone amplifier A21 to the speaker SP1 via a power amplifier circuit A12, and the voice of the passengers at the rear seats S3-S6 can be vocalized from the speaker SP1 in the neighborhood of the driver seat S1 in such way. Thereby, it is possible to clearly hold the conversation between the driver seat and the rear seat even when a comparatively large noise exists in the vehicle.

The perception of complex acoustic patterns in noise by blue monkey (Cercopithecus mitis) and human listeners

Abstract: Blue monkeys (Cercopithecus mitis) were trained to detect acoustic signals embedded in noise. Masked thresholds were determined for four hu consonant-vowel speech sounds (6a, pa, ga, and ka), and four blue monkey (boom, pyow, chirp, and trill). The ability of monkey listeners to hear these was compared with humans. Results showed that monkey and human was very similar. The mean difference between species for these eight stimuli in broad-band noise environment was 2.3 dB. The signal-to-noise ratio for ranged from 4.8 dB for the ka to -23.8 dB for the boom. The four monkey calls audible at a signal-to-noise level that was 8.1 dB less than that required for the the speech sounds. However, most of this effect was due to the audibility of boom. With the boom excluded, the mean signal-to-noise ratio for detection of the re 7 sounds was -0.5 dB, and the mean difference in the audibility of and monkey sounds within this set was 2.6 dB. These results contrast findings which used simulated rain forest noise as the masking noise (Brown, 1986). rain forest noise, test signals were audible at signal-to-noise ratios approximately dB less than those reported here, and the observed difference in the human and monkey utterances was larger. These findings variations in the amplitude and spectrum of the ambient noise may have influence on the audibility of vocal signals in nature. a strong suggest that rather small relative audibility of 10 In with previous the speech maining the detection of were perception the hearing signals in noise calls man complex

Sustained peripheral vasoconstriction while working in continuous intense noise.

Abstract: The study examined the effects of exposure to continuous noise on pulse volume (vasoconstriction) and rate, as well as four-choice serial reaction time. There were 2 separate groups of 12 subjects that performed the 20-min task during simultaneous monitoring of their physiological response to continuous 93 dBA white noise or 70 dBA quiet control conditions. Pulse volume showed marked reduction, implying increased arousal, in the first 3-min exposure to noise. Although some habituation of the vasoconstriction response then occurred, pulse volume continued to remain significantly higher than in quiet throughout the work period. Serial choice performance was unaffected by noise. The results confirm that there is a physiological cost incurred when working in noise and one may be concerned for long-term effects on noise-exposed people.

Shaping circuit for digital vol. command in audio systems - uses low-pass filter that avoids clicking noise when sudden change, in volume occurs

Abstract: An amplifier for audio signals responds to a required volume command that may change suddenly and resulting in a transient clicking noise. The audio data are combined with the volume command in a multiple stage and the output is fed to a D/A converter. The transient noise effect is avoided by using a filter to process the volume command data such to produce a smoothing action. The filter is of a first order type with a time constant that can be varied. ADVANTAGE - Provides smoothing characteristic to eliminate clicking effect.

Perception of American‐English in noise by Greek listeners

Abstract: This study examined the ability of Greek listeners to understand American‐English in noise. The speech perception in noise (SPIN) test was administered at 75 dB SPL in the presence of babble noise to 23 Greek and 10 American listeners with normal hearing. The Greek listeners had studied English for an average of 8 yr and lived in the U.S. for an average of 2.5 yr. Noise levels were chosen in 3‐db steps to encompass the range from 20% to 90% correct performance. At each noise level, 50 new sentences were presented and the percent correct for 25 high‐ and 25 low‐predictability sentences was measured. Results show (1) the slope of the psychometric functions in terms of Z score per decibel of speech‐to‐noise ratio was steeper for the native than the Greek listeners, (2) the native listeners could obtain 50% correct performance at significantly higher noise levels (about 3 dB) than the Greek listeners, (3) both groups performed significantly better on the high‐predictability sentences than on the low‐predictability sentences, and (4) the difference in tolerable noise levels (levels yielding 50% correct) between the high‐ and low‐predictability sentences was the same for both groups. These results corroborate earlier studies with other non‐native languages [e.g., Florentine, J. Acoust. Soc. Am. Suppl. 1 77, S106 (1985)].

Speech recognition in a noisy and reverberant environment with and without earmuffs.

Abstract: The effect of earmuffs on speech recognition in conditions comparable to an actual environment was studied with the use of sentences, words and nonwords. The speech level was adjusted to 60 and 85 dBA. White noise was used at signal-to-noise ratios (S/N) of 0, +5, and +10 dB. The reverberation times were 2.1 and 1.6s. In quiet conditions at normal speech level (60 dBA), the perception was better without earmuffs than with them. At a high noise level, equal or better scores were achieved with ear protectors. At high speech and noise levels (85 dBA, S/N 0), the benefit of earmuffs was clearly demonstrated. Also with longer reverberation, the use of ear protectors increased the perception scores, especially at high speech and noise levels.

Sound volume adjusting method for av apparatus

Abstract: PURPOSE:To increase and decrease the sound volume even if a silenced state is set by a silencing means by providing a sound volume adjusting means and the silencing means, and outputting a display signal corresponding to magnitude of an audio signal inputted from the sound volume adjusting means. CONSTITUTION:A silencing means 4 for attenuating temporarily an audio signal outputted from a sound volume adjusting means 3 is provided. In such a state, at the time of a silenced state, a sound volume display signal corresponding to a sound volume set value is sent to a display means 10 together with a display signal of the silenced state, and together with a display of the fact of being in the silenced state, a standard of a control state of the sound volume is displayed. In such a way, even if an audio part of an AV apparatus is in a silenced state that the sound volume is attenuated temporarily by the silencing means 4, the sound volume can be increased and decreased without emitting a sound from a loudspeaker 6 by a sound volume increase/decrease command from a key input mans 9 or a remote control signal receiving means 8, and the sound volume of its time point can be confirmed as a standard of a sound volume control state by the display means 10, therefore, the AV apparatus can be operated without giving trouble by noise.

The effects of noise on vision efficiency.

Abstract: The aim of this study was to determine the relationship between intensity, noise duration and non-auditory effect represented by changes both in visual acuity and the near point of accommodation. Changes in vision efficiency determined by a black and white chess board were monitored during and after 1 h exposure to 4 levels of noise: 90 dB-A, 93 dB-A, 96 dB-A or 99 dB-A and 2 h exposure to 96 dB-A. Results indicated that vision impairment can be attributed to a complex relationship between the intensity and the duration of exposure to noise.

Pattern recognition within spectrally isolated regions of broadband complex sounds

Abstract: The iteration of recycled noise segments (RNs) can be heard readily at infratonal repetition frequencies (below 20 Hz,) with “whooshing” (which becomes resolved into components such as “thumps” and “clanks”) heard from 1–4 Hz and “motorboating” (involving a featureless timbre) heard from 4–19 Hz [Guttman and Julesz, J. Acoust. Soc. Am. 35, 610 (1963)]. As previously reported, repetition is heard at all center frequencies when a 1/3‐oct filter is swept through broadband motor‐boating or whooshing RNs. The present study examined the recognition of individual RNs presented first with limited spectral bandwidths, and then embedded in broadband “parents.” Accurate performance required bandwidths greater than a critical band and center frequencies less than 4.8 kHz. These results, and those from a second experiment involving identification of narrow‐band derivatives of previously heard broadband RNs, will be discussed in terms of (1) the relative contribution of different spectral regions to recognition of long‐period waveforms and (2) the ability to perceptually segregate broadband patterns into discrete spectral regions. [Work supported by AFOSR and NIH.]

Radio with message reception indicator

Abstract: A radio (10) measures and stores (16, 18) the ambient sound (or noise) level of its environment. When a message is received, the current noise (or sound) level is compared to a threshold (56). If the ambient noise level is such that an audible tone may not be heard by the radio user, a silent alert is automatically activated (62) regardless of whether the silent enunciator has been previously selected (enabled) by the radio user. In another aspect of the present invention, if the ambient noise level is such that an audible tone may be inappropriate (i.e., library, courtroom, or certain hospital areas), the silent alert is also automatically activated regardless of whether the silent enunciator is enabled so as not to disturb others.

Tape hiss noise removing system in tape sound recording and reproducing device

Abstract: PURPOSE:To uniformly remove a tape hiss noise without changing a sound recorded original signal even when a different tape sound recording and reproducing device is used by executing a compressing operation for the signal at sound recording time and an extending operation for the signal at reproducing time according to digital processing. CONSTITUTION:In a sound recording part 1, an inputted audio signal SA is extracted and converted into a digital signal SAD, and for example, the high frequency part of the digital signal SAD is emphasized based on the peak value of the output signal of the sound recording part 1 set as a control signal and converted into an analog signal. In a reproducing part 2, a read out signal read out from a magnetic tape 5 is extracted and converted into the digital SAD signal, and for example, the high frequency part of the digital signal SAD is attenuated based on the peak value of the digital signal SAD set as the control signal and converted into the analog signal. Consequently, when the high frequency part emphasized at the sound recording time is attenuated for the emphasized amount and reproduced as the original audio signal SA, the level of the hiss noise is relatively reduced. Thus, the tape hiss noise can be uniformly removed in the tape sound recording and reproducing device.

Noise in Open-Plan Computer Rooms:

Abstract: Noise in open-plan computer rooms and annoyance associated with it was reported to be a problem in a large service organization. An experimental investigation was undertaken to determine noise levels in this organization's computer rooms. The noise spectrum was found to be similar in all facilities investigated but substantially different from those of open-plan offices. Fifty percent of all respondents rated the noise level (on a 25–point scale) between extremely annoying and unbearable and intolerable; 10% of the respondents considered the noise very annoying; 20% of the respondents considered the noise levels moderately annoying; the remaining respondents did not seem to have a major problem. Conversational sound and computer-printer beeping sounds were reported to be most annoying by 90% of the respondents who considered the noise levels annoying.

Spectral Shaping During Acquisition of Seismic Reflection Data

Abstract: It is the purpose of this paper to point out the difference between ‘broadband recording” and “recording broadband data” in reflection seisrnoicgy. There can be a significant difference, and it should be noted that broad-band recording does not always result in broad-band data. Conversely, narrow band recording does not always result in narrow band data. The information transmission rate of any discrete passband is never increased by data processing. All that can be accomplished in data processing is to imorove the sianal to noise ratio bv eiiminatina part b the noise and s&iing up theamplitude of the remaining sigiai. Consequently, it is in the best interest of the reflection seismologist, who deals in no more than a few seconds of data transmission from each shot, to transmit as much information as possible into the usable passband in the field prior to A/D conversion. This can sometimes, but not always, be accomplished by careful selection of analog filtering in the field prior to analog to digital (AID) conversion. Commonly, the upper band-edge of the recorded spectrum can be pushed upward by IO to 30 percent by shaping the recording spectrum prior to A/D conversion.

Voice recognizing device

Abstract: PURPOSE:To attain a high recognition rate without receiving the influence of ambient noises by generating noises by a noise generating means at the time of registration and comparing a standard voice characteristic pattern with a previously recorded input voice characteristic pattern in the same environment as the environment at the time of recognition, and thereby recognizing the above-mentioned pattern. CONSTITUTION:A white noise signal generating section 3A generates a white noise electric signal N by receiving the instruction signal CN from a control section 2A when a switch 1 for registration is pushed. A speaker 4 converts the signal N to the white noise and outputs the same. The white noise is thus superposed on the voice of a specific speaker. This voice is passed through a microphone 5 and an analyzing section 6 and is thereby made into the standard voice characteristic pattern which is stored in a memory 7 for the standard pattern. A recognition mode is automatically started after the end of the registration. The voice inputted from the microphone 5 in the state of not operating the white noise signal generating section 3A and the speaker 4 is set through the analyzing section 6 and a memory 8 for the input pattern to a recognition section 9 where the voice is compared with the standard voice characteristic pattern and the inputted voice pattern is recognized. The influence of the ambient noises is eliminated in this way and the high voice recognition rate is attained.

Fm stereo receiver

Abstract: PURPOSE:To convert a reproduced sound with much noise or distortion into an audio signal comparatively easy to listen to by varying separation and a high frequency with an output from a level detection circuit detecting the level of an intermediate frequency signal or a detuning detection circuit. CONSTITUTION:A separation control circuit 8 and a frequency characteristic control circuit 9 operated when an antenna input level is lowered provided to the receiver. When an output by detuning detection circuits 14, 15 is changed, the separation of left/right audio signals is varied continuously in response to the change and when the output by the detuning detection circuits 14, 15 is changed, the frequency characteristic with respect the audio signal is varied continuously in response to the change. If an unpleasant reproduced sound with much distortion is about to be reproduced, the separation of the left/right audio signals is reduced in response to the detuning state and the audio signal with less noise is reproduced and the level of the high frequency component of the audio signal is reduced in response to the detuning state to cut off the noise component. Thus, the audio signal comparatively easy to listen to is reproduced.

Road traffic and interior noise: a survey of noise levels in houses exposed to traffic noise

Abstract: A large number of people are exposed to excessively high levels of traffic noise within their homes and conventional housing design and construction practices are not sufficient to reduce traffic noise to acceptable levels. The substantial differences between the Australian Standard requirement and the measured levels, differences up to 17 dB(A), suggest that traffic noise levels within homes of conventional design can be excessively high. The Quiet House illustrates that it is possible to build dwellings next to major roads and still retain an acceptable living environment. As a part of the NSW State Pollution Control Commission's traffic noise control program, the Quiet House project was designed to inform all sections of the community about the viability of good housing design for traffic noise control (A). (Interior Noise Climates; Conference Proceedings)

Recording method for still picture recording/reproducing device

Abstract: PURPOSE: To prevent the occurrence of inconvenience in a sound signal, which occurs at the time of video release by recording the sound signal collected before video release in correspondence with the video signal. CONSTITUTION: When a sound collection switch 52 is turned on and the desired sound signal is collected, the sound signal is stored in RAM 45 in the same way as the case of a normal mode. When a video release switch 36 is turned on and the video signal is stored, the video signal is recorded in the prescribed track of a magnetic disk 12 in the same way as the case of the normal mode. When the recording completes, a magnetic head 15 immediately moves to an inner track by one and the collected sound signal is recorded here. Thus, it can previously be prevented that noise occurring at the time of video release is mixed in the recorded sound signal and the occurrence of inconvenience on the sound signal such as the distortion of the sound signal accompanied by the deterioration of the voltage can previously be prevented. COPYRIGHT: (C)1992,JPO&Japio