Showing papers on "Noise published in 1986"

Apparatus and method for calibrating recording and transmission systems

Abstract: An audibly distinctive test signal provided by a generator (6) is a pink noise signal at a standard level with periodic but brief interruptions (optimized for the ear's memory for level and spectral differences) acting as an identifier. The test signal is applied to a recording medium or transmission channel (14), preferably via an equalizer (16) and gain setting means (181. The test signal recovered from the recording medium or transmission channel by playback or receiving means (22) is compared and matched to a reference uninterrupted pink noise signal provided at a standard level by a generator (24). The interruptions are used to switch between the test and reference signals and to provide via equalizer (34) and speaker (28) an audible cue as to the identity of the signal heard at any moment so that a rapid confirmation and adjustment, if necessary, of recording/reproduction or transmis- sion/reception calibration can be achieved primarily by ear and, if desired, also by applying the signals to measuring instruments, such as a meter (30) and spectrum analyser (32).

Noise reduction system

Abstract: A noise reduction system and method for reducing noise occurring during pauses in information bearing audio signals has an audio input connected to one input of a differential output circuit. A variable gain circuit has an input connected to the audio input and an output connected to the other input of the differential circuit. A dc control signal is derived from the incoming signals and controls the variable gain circuit to cause cancellation of a noise only signal during periods of no information bearing audio signals.

A critical load for nocturnal high‐density road traffic noise

Abstract: Eighteen female and 18 male students (21-30 years) slept in the lab during 12 consecutive nights each, where a high-density road traffic noise was played back with four intensities. EEG and EOG were recorded continuously throughout the nights. In the morning the subjects assessed their sleep and completed a reaction time test. The following conclusions were made: Performance was not affected by noise. REM sleep decreased abruptly as soon as the sound pressure level exceeded 44 dBA. With increasing noise, sleep was assessed as increasingly worse. Noise-induced sleep disturbances were not related to sex. The equivalent sound pressure level measured for high-density road traffic seems to be a valuable predictor for subjective sleep disturbances as long as the maximum levels do not exceed it by more than 8-10 dBA. On the basis of the assessment of sleep and supported by the abrupt decrease of REM sleep, an equivalent noise level of 40 dBA indoors was defined as a critical load, above which nocturnal noise cannot be tolerated any longer. Language: en

Optical sensing circuit for audio activation of toys

Abstract: A noise-generating toy includes first and second optical sensors to detect the intensity of light in first and second optical fields, respectively. The sensor signals serve as inputs to a comparator which provides as an output a differential signal indicative of the difference between the sensor outputs. The comparator output drives an oscillator which generates audio signals in response to the differential in the intensity of light. The oscillator drives one or more speakers with the audio signals, and the speakers use the audio signals to produce audible sound or noise.

Quantum noise in spectral filtering of light

Abstract: The quantum-theoretical description of the action of a spectral filter is given. It is shown that spectral filtering of light is unavoidably connected with quantum noise, which prevents the spectrometer from performing a Fourier analysis even under ideal conditions. The quantum noise is important in the study of spectral properties of nonclassical light fields, such as spectral squeezing in single-atom resonance fluorescence.

Selective modeling of the LPC residual during unvoiced frames: White noise or pulse excitation

Abstract: This paper presents a new method of modeling the LPC residual during unvoiced speech for voice coding at 4.8 kb/s. With this method, speech is synthesized using one of three excitation types: periodic pitch pulses, random noise, or multipulse. By using multipulse excitation it is possible to accurately produce speech which is difficult to model using noise and pitch pulses alone [1]. Since multipulse is only used where appropriate, efficient, sub-optimal methods of calculating the pulse amplitudes and positions are adequate, simplifying the implementation into a real-time system. The synthetic speech may be coded at 4.8 kb/s since multipulse, used only where appropriate, suffers little quality loss when quantized. A method of determining which excitation type is to be used is discussed. Formal listening test results are also presented.

Effects of auditory masking by white noise on variability of fundamental frequency during highly similar productions of spontaneous speech.

Abstract: Six adults (3 men, 3 women) produced highly similar spontaneous speech utterances during quiet and 90-dB SPL white noise. Although subjects' fundamental frequency (fo) was significantly increased when speaking in noise, their fo variability (coefficients of variation) throughout the utterance was not affected by the auditory disruption. This indicated that their ability to vary fo for linguistic stressing was preserved under short-term disturbed auditory feedback. These findings further supported the hypothesis that fo is under open-loop regulation.

Noise reduction circuit for reducing pulse noise in audio signal reproduced from a recording medium

Abstract: A noise reduction circuit is provided with a slew rate detection circuit for detecting a slew rate of a reproduced audio signal, and variably controls a pulse width of a hold signal depending on the detected slew rate. The noise reduction circuit successively produces the reproduced audio signal with a predicted level other than a level of pulse noise included in the reproduced audio signal during a time period corresponding to the pulse width of the hold signal, so as to obtain a reproduced audio signal in which the pulse noise has been eliminated.

Analysis of a moving sound source - compensation of the Doppler effect

Abstract: To control the noise from a specific noise source, we need to study its spectrum under operation of noise source. To analyze the noise radiated by a moving noise source, it is difficult to observe the original spectrum of noise because of the Doppler effect. In this paper, we propose the analyzing method of the spectral information which reduces the frequency shift of observed signal. The compensation of the Doppler effect is realized by compensating the propagation delay between noise source and each observer, which is equivalent to the orbit information when the sound velocity Is known. To evaluate the performance of this method, a simple model experiment was carried out. Also the errors in the reduction of the Doppler effect and requirement of this method are considered.

Audio system including an electromechanical vibrator controlled in accordance with ambient noise

Abstract: Driving apparatus for an electromechanical vibrator 10, which is disposed on a chair or seat 5, uses an audio signal applied from audio equipment A. The initially set strength of vibration is compensated in accordance with environmental noise, which is detected by noise detecting means 24. The person sitting on the chair or seat thus enjoys, e.g., music by ear and body vibration. The noise is detected by a microphone 241, low-pass filter 242, amplifier 243 and rectifier/integration circuit 244 and is used to control the gain of an amplifier 241 feeding the audio signals to the electromechanical vibrator 10.

Apparatus for recording and reproducing a video signal and an audio signal

Abstract: An apparatus for recording and reproducing a video signal and an audio signal (which are recorded in different areas or portions of each slant track on a tape) includes first and second rotary heads (H 1, H2) for recording and reproducing the video and audio signals in alternate tracks, and a playback circuit (2, 3, 4) for processing luminance and chrominance components of the video signal reproduced by the first and second rotary heads (H1, H2) when scanning video signal-containing areas of the respective tracks. The apparatus also includes a circuit (20) for supplying a new audio signal from an input terminal (19) to the rotary heads (H1, H2) for recording, a signal generator (7) for generating a predetermined signal to be substituted for the processed luminance component, and a muting circuit (15) for muting the reproduced chrominance component. The predetermined signal from the signal generator (7) is substituted for the processed luminance component, and the chrominance component is muted by the muting circuit (15) during recording of the audio signal in place of a previously recorded audio signal, thereby suppressing noise bars which might otherwise appear in the reproduced picture.

Broadcasting instrument in carriage

Abstract: PURPOSE:To obtain proper broadcasting output and to simplify circuit configuration of the equipment by eliminating influences of entering of broadcast voice itself using silent sections of broadcast voice that occur relatively frequently and detecting noise level having large correlation with noise felt by passengers. CONSTITUTION:When broadcast voice level arrived at voiced level, the output DET' of a level detecting circuit 8 drops suddenly to L level and a register 5 holds a value L1 obtained by the latest pulse of a sampling clock SCLK as the value of voice level G. Accordingly. in a section where broadcast voice is voiced level, the gain of a gain controlling circuit 10 is controlled by the value of G corresponding to the value L1 of extraneous noise level signal just before arriving at voiced level. When the broadcast voice disappears and this is detected by the level detector 8, the output DET' returns to H level again after a fixed time tau and the value of D' obtained after the first pulse of SCLK is sampled and the output is generated successively as Ln, Ln, Ln+1,... as shown in G.

Some phonetic characteristics of sentences produced in noise

Abstract: This study is concerned with changes in the acoustic‐phonetic structure of isolated words produced when the talker is in a high‐noise environment and/or is wearing equipment that produces an obstruction to articulation, eg, an oxygen mask The speech of four young males was recorded in three conditions: quiet (laboratory recording conditions), while listening to white noise at 95 dB SPL over earphones, and while listening to the same noise levels introduced into the earphones of a standard Air Force helmet equipped with an oxygen mask Speech produced while listening to noise over earphones alone showed the expected increases in fundamental frequency and amplitude In addition, the duration and formant structure of vowels, and to a lesser degree the timing of consonantal gestures, changed when speech was produced in noise Preliminary indications are that speech produced while wearing a helmet and oxygen mask was minimally affected by noise introduced over the headphones [Supported in part by AFOSR]

A Survey of VHF Man-made Noise in the Metropolitan City Area of New Delhi

Abstract: Multiple sets of man-made radio noise data are reported for a number of locations in the metropolitan city area of New Delhi. These are examined to assess the frequency, distance and diurnal characteristics of the composite city noise for urban locations. The measurement was restricted in the frequency band of 50-100 MHz to observe the impact of noise on VHF land-mobile and TV broadcasting services. The incidental noise environment to be experienced by these services at different busy activity zones of the city is observed to have a contrasting spectral pattern.

Recorder control system

Abstract: PURPOSE:To enable only a program for which its recording is desired to be recorded by transmitting a signal noise with a specified frequency at every start and every end of a CM in a television program or the like and controlling the start and end of the recording in a recorder. CONSTITUTION:A signal noise with a frequency not more than 20Hz that is the minimum for a human's audition is transmitted together with a pictorial image and a topic just before or just after a CM or at every topic in a program from a broadcasting station. On the other hand, using the timetable of a program on a newspaper, weekly musical journal or the like, every program and every topic in the program are numbered and the number is adapted to correspond to the signal noise. When a program with a given number is to be recorded by a video deck, after appointing a date and a channel, the number entered on the side of the timetable is inputted. Thus, only the signal noise corresponding to the number of the appointed program is responded, whereby only the program for which its recording is desired can be recorded.

Secam type magnetic recording and reproducing device

Abstract: PURPOSE:To suppress limiter noise and to prevent a screen from disorder even if standard time recording and long time recording are switched each other by setting up the superposing ratio of a luminance signal component of a video recording current to a chrominance signal component almost equivalently at the standard recording time and the long time recording. CONSTITUTION:A Tr switching circuit block 32 for reducing a recording current level is connected to the outputs of color signal and recording current adjusting volumes 29, 30 through resistors R3, R4 respectively at the long time recording, so that DC level of the input signal 31 is increased at the long time recording and the Tr is conducted. At the standard time recording, a luminance signal recording current is adjusted to the optimum recording current of a standard time magnetic head by the volume 29 and the chrominance signal is adjusted at its level by the volume 30 to suppress the generation of noise. At the long time recording, R3, R4 are selected becase of the conduction of the block 32, so that the ratio of the luminance signal recording current can be automatically set up to color signal recording current of the optimum recording current of a long period magnetic head and the chrominance signal recording current can be automatically set up to almost the same ratio as that of the luminance signal recording current to the chrominance signal recording current at the standard time recording.

Effects of Noise on Growth, Egg Laying and Mineral Contents of Egg Shell in Hens

Abstract: 餌付後6週齢のヒナ20羽を防音室内に収容し,白熱電球の全日点灯による照度40ルックスのもとで,約2週間予備飼育の後,10羽を対照区(C区),残り10羽を騒音区(N区)の2群に分けた.ついで,N区のヒナに対して,録音した道路上の自動車エンジン音を70～75ホーンの範囲で,1時間負荷と1時間休止とを反復し,21週間にわたって騒音を負荷した.さらに騒音停止後3週間観察した.これらの期間,体重,産卵数および卵殼重量を記録し,また卵殼中のCa,MgおよびP含量を測定した.1. 騒音負荷開始後の各週の平均体重は,C区に比しN区が常に少なく,週齢が進むにつれて,その差は大きくなり,特に,20,21よび22週齢における平均値の差は大きく,126,147および143gであった。2. C区の各週の体重の棄却下限以下のN区の個体数は,13週齢以降の各週において1～4羽であった.3. 騒音負荷によって,N区の産卵開始はC区に比しやや遅れる傾向があった.4. C区の週平均産卵率に比しN区のそれは低くその最大の差は20%であった.5. 卵殻無機質含量についすは両区間に有意の差は認められなかった.6. 騒音負荷停止後のN区の体重および産卵率はC区の値に接近あるいは逆転し,両区の差は縮小した.以上の結果から,騒音負荷によって,発育が抑制される個体が現われ,特に,19～21週齢において3羽(30%)にそれが見られ,このことがN区の初産卵の遅れおよびその後の産卵の低下をもたらしたものと推測される.

Audio device for car

Abstract: PURPOSE:To obtain an audio device that can transmit accurately the hearing contents to a listener by controlling properly the sound volume and the loudness correction degree in accordance with the variation of the noise level, the speed level of a car and the conversation level respectively. CONSTITUTION:A DC control pat 13 averages the signals detected by a noise sensor 1, a conversion level level detecting microphone 6 and a car speed sensor 10 and delivers the control signal VC to a sound volume control circuit 14. The signal VC controls the circuit 14 toward increment of the sound volume in response to the increase of both the noise level and the car speed. While the circuit 14 is driven toward decrement when the conversation level is in creased. At the same time, the signal VC controls a sound quality control circuit 16 via a switch 15-2. This switch 15-2 is switched to the lower side in an increase mode of the conversation level. In this case, the circuit 16 is controlled so that the loudness correction degree is reduced according to the increase of the conversation level.

Noise evaluation in broadcast listening

Abstract: A few reports on the interference with radio or television listening were presented by means of the social surveys, but there are few investigations on noise evaluation in broadcast listening. This study aimed at obtaining the noise evaluation in broadcast listening and the relation between annoyance of noise and physical parameters such as types of noise, noise level, average frequency of occurrences, and so on. Three types of noise; steady noise, intermittent noise, and impulsive noise, were used in the experiment. Broadcast program was the reading of novels and music. The results showed that the annoyance of the steady noise, the intermittent noise and the impulsive noise was almost determined by Leq in broadcast listening. Investigated in detail, however, the results showed that the steady noise was the most annoying, the intermittent was the next, and the impulsive was the least annoying.

Effects of Auditory Masking by White Noise on Primary Stressing during Spontaneous Speech

Abstract: 6 adult subjects (3 men, 3 women) produced highly similar spontaneous speech utterances in quiet and with 90-dB SPL white noise. The frequency of occurrence of perceptual judgments of primary stressing in an utterance was not affected by the masking noise. This finding supplements our previous report that variability for stress production of fundamental frequency (fo) during spontaneous speech was preserved under short-term auditory disruption. Also, it adds further support to the contention that fo is under open-loop regulation.